I MADE A MISTAKE: I stated that if you add more light bulbs in parallel the bulbs will be dimmer because the resistance will go up. The light bulbs *will* be dimmer if more are added in parallel but not because the total resistance increases. In fact, the total resistance will decrease as they are in parallel. The bulbs are dimmer because more current is being drained from the generator and the internal resistance means that the *voltage* over the individual bulbs will decrease. I am so sorry, I should have realized what was happening with a bit of thought. Also, now that it is up, I cannot edit my video (although I did add a little card in the corner). Also, many of you were confused by my quick transition between Edison's 3-wire DC and Westinghouse's and European AC systems. I should have been more clear about when that transition happened, sorry.
Caught that right away, was about to stop watching thinking this chick is way over head, but you proved me wrong. Bottom line, it's all about the wire thickness. For a given amount of power used, the higher the voltage, the thinner the conductor. Also the rest of the world uses more aluminum wiring, less expensive than copper, but lesser ampacity. All this talk about AC electrical transmission, and no mention of Tesla?
I love your enthusiasm, but showing photos & graphs then throwing your bare white contrasting hands around makes the transition from one to the other less than palatable. Thanks 🙏🙂Maybe wearing darker apparel would be all that’s needed. This is wonderful show!
@@barrywhite9114Kathy has explained that she was diagnosed with ADHD and that moving her hands is, for her!, a necessity to be able to think. I recommend to watch that video.
_"People like you make UA-cam awesome."_ There are so many people, like her, that make UA-cam awesome that I prefer UA-cam videos to TV shows. I'm not only entertained, I'm also informed.👍
-Thanks for your hard work and research on this. The reason the Chicago Exposition was such a triumph for Westinghouse has to do with Edison refusing to sell lightbulbs to a competitor. That wonderful genius Nikola Tesla took a look at the problem, and invented fluorescent bulbs, which cut Edison out of the picture completely. That pretty much was the reason the "War of the Currents" came to an end, as AC could be distributed over thousands of miles, whereas DC was very much local-distance only. Edison gets far too much credit, and Tesla far too little.
I have to agree with you, that Nicola Tesla formed the basics of the AC Power Grid, but Edison took all of the accolade. Tesla died virtually penniless.
The other weird thing about Japan (well, the other weird thing about their power grid) is that half of it is 50Hz and half is 60Hz, because two different cities started electrification projects around the same time, one using American-built generators and the other using European equipment.
@@rickykngoall of Kanto, Tohoku and Hokkaido use 50hz. And all of Kansai, Chugoku, Shikoku, and Kyushu-Okinawa use 60hz. The Chubu region is split, where all of Yamanashi is 50hz, and all of Aichi, Gifu, Fukui, Ishikawa, and Toyama are 60hz. The prefectures of Shizuoka, Nagano and Niigata are where you can find both 50 and 60hz depending on the municipality. Where Shizuoka and Nagano are mostly 60hz, and Niigata is mostly 50hz.
I am a data com engineer. I am not an electrical engineer. I remember the fun (lol) of trying to calculate the energy requirements for data center PDU's which had 3 phase incoming, feeding both 48v dc networking gear + 1000+ servers @ 110v ac + sufficient battery capacity in AMP/hours + generator requirements beyond that, etc, etc, etc. I had to attend 2 weeks of classes with APC to learn some of what you explained in a few minutes. You do an excellent job of explaining things in an understandable manner. Kudos!
Over 1,000 servers? You could just replace it with 1 mainframe the size of a refrigerator, which can virtualise over 4,000 "servers" 1 machine v. 4,0000 the choice is clear
We use BOTH voltages in our US homes. All my heavy equipment uses 220 such as cooker hob, oven, A/C condenser unit, pool pump motors and clothes dryer. All regular light duty stuff is 120 which is more than enough for lighting, kitchen small appliances, tv, computers etc. I think our electrical system makes complete sense. Yes, we have electric kettles and toasters running happily on 120 too. I recall from 1975 when we first came to the US that my wife wanted to use her UK sewing machine so I wired up a connection to the cooktop 240 volt for her and she was able to get sewing.
You are correct. Most homes have at least 220v coming to them in the US. The neutral conductor allows us to ‘split’ that voltage into 2 110v legs. While 110v is less efficient, it’s physically safer to the user. There’s is a heck of a difference if you get shocked with 110 vs 220.
@@yolowolfyt no home needs three phase. Larger users such as public institutions, offices and factories all use three phase. Even my church uses three phase. Three phase power lines run through every neighborhood. If your small farm needs three phase for certain new equipment you can have it wired in. It’s just a matter of having an appropriate voltage for the need. I am happy to have a safer voltage of 120 for all normal outlets. With the advent of led lighting, flat screen TVs and small appliances the wattage needed goes way down anyway.
At 2:35, the correlation between loading and resistance is backwards. The more loads you have in parallel, the LESS resistance you have, not more. The reason why the "popular" lines weren't as bright is due to a higher voltage drop across the conductor. More current means higher I^2R losses.
Yes, I was unclear what she meant. If more loads are turned on then, from the point of view of the generator output terminals looking towards the loads, the system load resistance is reducing not increasing. As you say the losses in the distribution conductors will increase because the reduced load resistance causes more current to be drawn assuming a fixed generator output voltage . Hence I^2 R losses have increased and load resistance decreased.
@Patrick Ray You're absolutely correct. I was about to make the same comment and started by checking whether anyone else made it already. Another reason the "popular" lines were not as bright was voltage loss within the power source (in addition to the voltage loss you mentioned in the wires).
I agree Kathy has confused the correlation between resistance and load/demand current flow in a parallel circuit as illustrated. The more light bulbs on at the same time are going to reduce resistance in the circuit and allow more current to pass/require more current without exceeding the ability of the generator or a voltage drop would occur, dimming lights. Voltage drop being a symptom of insufficient generation or resistance between the generator and load. I don't know a lot about the Edison system [why I am watching this] but it seems it was a DC system rather than an AC system and I wonder if it also a series circuit system rather than a parallel? That would explain increasing resistance as more lights/load was added.
09:00 Oriel Chambers, Liverpool, built in 1864 is regarded as the first steel framed building in the world, and the design principles were brought back to Chicago by architect John Wellborn Root who was studying in Liverpool as a teenager, during the time of its construction.
There was the Shrewsbury Flaxmill building built by Charles Bage back in 1797. Cast iron, rather than steel but served the same purpose of being A) fireproof and B) offering maximal interior floor area for the industrial machines. It still stands, worth a visit.
I enjoy your discussions on the history of electricity. My dad, like me was also an electrical engineer, said that in the early days of development of the light bulb, it was difficult to make the filiment thin enough for a higher resistance to run on 100 volts. The tungsten filiments were coiled to keep them compact so they didn’t have to have wire supports in the lightbulb. The 220v made the light bulb more difficult to make. Years later by better manufacturing techniques, they were able to make thin high resistance filiments. The 7watt candelabra light has a really fine filiment that was fragile and it took even longer to develop. When I grew up in the 1950s, when decorating Christmas trees with these bulbs the filiments would break easily when dropped. Remember that the only use for electricity in the early days was for light bulbs, so making practical filiments was important.with time light bulbs got smaller, but they were then made for lower voltages and ran In series. PS I worked in two Silicon Valley laboratories where they developed the first practical LEDs in the late 1960s, that is Fairchild semiconductor and HP laboratories. HP first used them in the HP-35 calculator. “You could get them in any color as long as they were Red”! To paraphrase Henry Ford. Ross
Maybe you should visit Cragside one day (the first house in the world to be lit by electric light) to disabuse you of the notion that it was only for lighting.
Please do some research on electrical distribution as it is why we have what we have. Also, check upon what 2 phase ac consists of. Just because one system identifies 2 phase conductors does not make the service 2 phase. 240/120vac single phase as provided as residential services occurs in almost all homes in the US. 2 phase distribution consists of 5 wires. Alternators are used for ac distribution. Generators are strictly dc.
Nice explanation! Skyscrapers also needed power for elevator motors, without which there would have been no market for buildings over 3 or 4 stories. The side story of Otis Elevator and particularly of Otis's initial emergency brake system (which was little more than a carriage leaf-spring) is fascinating, and he too presented his invention at the Worlds Fair. I read once that with dozens watching, he would stand in his demo elevator and with a chop of his axe, he would cut the rope holding up his elevator car. Instead of crashing to the ground, which was VERY common in those days, Otis's demo car would only fall a couple feet before that leaf spring would open up, lock into the shaft structure itself and stop the car, he sold beaucoup elevators and cemented his legacy in history. And separately from that, plumbing eventually DID make it to downtown buildings, not only to provide water for the humans to drink or to flush with in the buildings, but also to provide water for firefighting purposes; probably something that Chicagoans were super in favor of after The Great Fire. Even today, we still use gravity and the "column of water" method to provide steady pressure and flow to every faucet, tap, or toilet in a building or area, and the best way to do that is to use electrical pumps to push the water up into a water tower for supplying a wide area, or up a building for storage in one or more tanks on the roof for supplying that building. It would certainly be preferable to have running water (even if it's not heated!) than it would be to carry a nearly 43-pound 5 gallon bucket up the stairs to your office desk or factory station every morning for your day's expected water needs! Electricity was for so much more than mere lighting. So as Paul Harvey used to say, "...and THAT is the rest of the story".
You don’t need electric power for lifts. Hydraulic power works perfectly well (and was standard in most European cities until the 1940’s). Hydraulic power lines were more vulnerable to bomb damage however. The old high pressure water mains were repurposed in the 1980’s for telecommunications conduit.
@@allangibson8494 Only if you have short elevators, taller buildings would require that the piston be potentially hundreds of feet below the bottom of the elevator. The freight elevator of one of the local buildings has a shaft of roughly 900 feet, meaning that the piston would need to be at least that long and buried to that extent. And the other elevators would need to have shafts of closer to 400 feet going through many floors. AFAICT, around here somewhere around 4-5 floors is where it starts to become a bit more of a toss up as to which technology to use.
USA uses 240V, check all the house fuse box, it's 240V at the entry point. We just split it 120V and 240V as needed for what ever appliance is rated for.
@braxtez3745 I am in Australia now. Didn't realize 240v was standard here. Even car 12v inverter is 240v. I forgot my 12v inverter home and had to buy one in Australia. Luckily the laptop charger takes both 120v and 240v so no worries but the plug is different as US uses two vertical plug while Australia has two angles. Found an adapter and it's working out well.
What is not commonly known is that Germany used to have a 115V+115V AC system when the Schuko plug was first developed although there was never a 115V + neutral version. It is why, to this day, in those countries where the Schuko plug is standard, like Germany and the Netherlands, domestic outlets are not polarised. Whilst there is a neutral + live(hot/line), it's completely random which pin is which when plugged in (which isn't a great mix with Edison screw light fittings as there's a 50:50 chance which way a table lamp will be plugged in (and it also means that there's a 50:50 chance than any single pole switch will be on the neutral). These days it's different in Germany and the Netherlands where they tend to supply domestic properties with three phase and tap off individual single phases at 230V for circuits (although more powerful appliances, like ovens, will often have more than one phase connected). Such is the way with legacy systems (of course North America didn't used to have polarised receptacles either; that was introduced later by widening the neutral blade).
This reminds me when living in West Germany in 1955, ("Army Brat"- Dad was assigned there.) the German house we occupied had 110 (115?) volts electrical service. That meant we could use our U.S. made appliances without requiring the use of step-down transformers. This just required Schuko to Edison socket adapters. Then, one day, teams of electricians (lineman) rewired the village of Bad-Windsheim for the then-standard of 220 volts. Dad was prepared with two step-down transformers and 220V light bulbs... We arrived home later in the evening and my brother and I had fun, running ahead of my father and turning on the lamps in each room and thrilling at such bright lighting for a few seconds.
Steve Jones I’ve always wondered why it was the neutral blade of the plug that widened instead of the hot? Is there more potential for heat on the neutral? Is that why it was decided to make that blade larger rather than the load blade?
@@deanbortz7747 Personally I've no idea. the current should be identical on both (or GFCIs would not work). In every other system I know of with polarised connections, such as those in Australia/NZ and the UK, the neutral and hot/line pins are exactly the same size. It's the shape of the plug that then ensures polarisation. In the case of UK plugs, they all have three pins and only go in one way. With the Australian system, the pins are angled so a two pin plug (as well as a three pin one) will only go in one way. As the addition of polarisation to the North American system was a retro-fit, then they had to maintain compatibility with earlier plugs and that was done by just making the neutral blade wider. I guess it could have been either. As a side note, the Australian plug design is the work of the same man as the classic North American plug, one Harvey Hubbell. What was later adopted as the Australian plug was designed and patented by him in 1916. He had intended that it replace his earlier plug (which he'd designed in 1912) as an improvement, but it never caught on. As is often the case, compatibility mattered more than functional improvements. Thus the Australians, who were later to electrification, standardised on that plug layout in 1917, reputedly because it was easier to manufacture in Australia than the British round pin plug which required solid brass pins rather than flat blades (the old British round pin standard is still in use in some countries, like South Africa and India).
@@TheEulerID In UK the Earth is connected to the "can" or "chassis". When I moved to Hanau from Norwich I was always careful how I plugged in my soldering iron. One day I forgot to take care and "soldered" 220v into my TV while repairing. The Eeprom "window" had black specks under it. ..... I will have to bike-ride that Lauffen-Frankfurt "3ph Trasse". I am 68. Cheers.
When in EE school I got some of the history shown here but it was new to me about the series DC generator/ 3 wire practice. I have worked in steel mills where it was not unusual to encounter motors from the 1910s and MCCs built in the 1920s. The control distribution of the DC to cranes was especially interesting. At 4.00 minutes the diagram reminded of a simple thing we did to monitor the Crane 240Vdc supply. We used 3 240V light bulbs, 1 wired leg to leg and the other 2 from rail to ground. Any fault resulted in a change in brightness to tell us to go find the fault. Working with technology from 1920s and up was a fun challenge. BTW some cranes still used control panels made in the 20s as late as 2010. The same crame had some mechanical parts that had patent numbers fron the 1890s. It was an adventure!
Your article on a new design of incandescent lightbulb (G2, 13 January) perpetuates the common myth that the original was invented by Thomas Edison. While a number of people were working on this at the time, it was the British scientist Joseph Swan who demonstrated the first viable incandescent electric bulb in 1878, some 18 months before Edison did. Edison, however, had the perspicacity to file his patents before Swan (and before he’d produced a working example). Dr Ian West Jackfield, Shropshire
And yet multiple court cases filed in US courts trying to break Edison's patent for the light bulb due to prior art all failed at the time for lack of evidence.
At 12:24 Kathy mentions higher-powered devices requiring higher voltages. I might add to her explanation: This same high power could be achieved with 120 VAC, but by stepping voltage up to 240 VAC the required current was cut in half (Power = Voltage x Current). Thus SMALLER CONDUCTORS could be used at 240 VAC vs 120 VAC.
@@GeirRssaak Conductors are sized according the the rating of the circuit breaker, which in turn is sized according to the load, and the amount of current required for the load. Other rules apply, but that is the basics.
Hello and thanks for this video. In Belgium, they went from 110 to 220 in the early 1950's. That's why old folks had huge auto-transformers at home if they wanted to use their old equipment.
@@m0r73n It happened in my city in the late 1970s, and the transition was quite smooth. Autotransformers were a no-no (and still are), we used "real" transformers with insulated windings. I don't think that the difference between 127V and 220V mattered much then. Residential consumption was very low, we did not have today's high-current toys like 10KW electric ovens and 20KW water heaters. My parents' apartment had a 20A (2.5 KW at 127V) input breaker and it never tripped.
@@jmi5969 Also 120V has a lower potential energy than 240V resulting in a lower risk of fatality and allowing for smaller and more space-efficient plugs.
@@davidperry4013 One other issue is arcing behaviour: the "american" 100-120V series arc is less persistent and ultimately less dangerous than the "european" arc. A collateral, probably unexpected, is that the European arc fault detetection devices are somewhat simpler and less prone to false positives than the American AFDDs. As for the size of power plugs - is there any need to make them smaller? our hands remain the same, and old folks likes yours truly aren't that good in handling small things.
Great video! Interesting info about filaments. One correction is that we do use 220V in the USA, it's just split at the home into 2 110V legs, just like the light bulb diagrams you presented. 220V is brought into every USA home from the pole.
220 v is phase to phase voltage, and 110 v is phase to neutral. From the pole the single household picks phase to neutral, while relatively large customers pick 3 phase and neutral, thus they have options: utilise 220 or 110 volts. 3 phase motors consume 220 volts - 3 phases without neutral, home appliances- phase and neutral 110 v. The 3 phase is essential when rotating magnetic field should be established in electric motors without commutator brushes.
@@lepton555 Noting that the 230V AC nominal is phase to phase from the 3 phase and not phase to neutral. In the UK and Ireland (which are all decidedly in Europe despite Brexit) at least the three phase is 415V. I am not sure you can even get 220V from 380V three phase.
That is exactly what we do in Trinidad and Tobago we use 110 v however 220 v can be connected from the panel with the 2 110v I currently have 1 220v plug for my washing machine and my welding plan
In the past 130V incandescent lamps were available for rural areas where the voltage was not that well regulated. An incandescent lamp burns out exponentially faster as the voltage increases and the higher voltage lamps would have a much longer life. Another trick before LEDs became popular was to use 28V lamps as indicators in 24V circuits. The indicator would not be as bright, but the lamp would last substantially longer.
They actually had invented light bulbs that would never blow do the manufacturers got together to make it compulsory for to have a set life time in hours for incandescent light bulbs ,the word for it now is opalescence
@@noelburke6224 While there is actually a word opalescence (meaning roughly glittering multi-colored) you probably meant planned obsolescence. There was never a light bulb which never blowed. However, in building a light bulb you have to find a compromise between efficiency (hotter is better) and live time (cooler is better). In order not to burden the customers with decision, the light bulb producers DID have a secret agreement on the bulb life time. Purely coincidentally, that did not harm profits.
Thank you for your great job. There is one mistake around 2:30. More lamps will make less resistance instead of more. And more current will drop the supply voltage and therefore dim the light.
I am so sorry that I had such a brain fart on that one, of course that’s why more lightbulbs in parallel will be dimmer. Thanks for correcting me so politely.
Hi from 240v UK... We had a novel experience a few months ago. A fault in the electricity 11kv distribution, left us with just 70 volts. However all our LED lights were just as bright at that voltage. Our 2Kw cooker elements would not heat up at that voltage.
many led lamps incorporate a constant current supply or regulator, dropping the line voltage (within design limits) will still result in same current delivered to the LEDs
Hi @@Admiral_Jezza It happened on the outskirts of the Wrexham Industrial Estate. I am still trying to work out why we went to 70v, and not zero. Maybe the 11Kv line only had a short on one of the phases. The arcing lit up the sky for several minutes, even though we were 5 miles away.
Great job. At 12:35 into the explanation about home electric dryer powering, there are not two phases here. There is only one pole transformer and only one phase of the 10 KV high-voltage tap. It is true that, in reference to the center tap, the two 120 volt ends are 180 degrees out of phase, yet still the dryer works on a single phase. It is not a 3-phase dryer.
Yep. That is why a point is made to call that split phase. As in being a split phase of a single phase. Or a single phase being split by transformer tap.
Very interesting with lots of history. I spent 50 years in electrical / electronic engineering and I've learnt new things watching this video! Thanks a lot, Colin UK
Great analysis. Lesser minds would have looked for whoever, in the entire history of electricity, happened to generate 120VAC first and just stop there. Kathy rightly realizes that it's FAR more important to follow the influence and adoption of an invention than just its first occurrence. Great stuff.
Interesting set of historical facts! When comparing 3ph and 1ph and 1ph/2legs (now called "split-phase") there are quite a few differences in how those are connected and work. For example in the Delta configuration there is no ground wire. You can get 120VAC on one node, 208VAC on two nodes, and 480VAC on all three. In the Wye configuration you do have a ground wire (so four wires instead of three) and that allows more redundancy if a phase failure occurs. Your typical 220-240VAC residential circuit used to be called "2 legs" not "2 phases" because the two hot lines were two circuits providing the same phase BUT opposite voltages. Now it's called "split phase" because --as you correctly point out-- if you call it like you see it, each of the hot lines is 180° out of phase with the other. The disadvantages to this is that there exist periods of 0VAC (every 1/60th of a second on 60Hz systems) whereas if offset by a real phase difference there would never be a 0VAC spot, but there would also never be a 2x1ph VAC spot either. Motors (HVAC equipment, pumps, etc.) like this more. However, water heaters and incandescent light bulbs don't like the 0s mixed in with the 240s. (And yes, there are plenty of 208, 277, and 480VAC incandescent lights... mostly industrial and businesses in the US.) Transformers are not cheap, so one of the compromises is what voltage to run to a residential neighborhood to save money on transformers. A 4KV-->240V transformer is much cheaper than a 14KV or 40KV downconverter. Things like compressors like 0VAC points (they are motors, after all) but things like welders don't. All of these are compromises. The reason for the compromise is the desire to run higher voltages to reduce amperage thereby allowing higher gauge wire (thinner) with a lower ampacity but saving money on copper or steel (must use even more steel for same ampacity). And finally, there are power-factor correction devices (think "huge capacitor banks") that store the energy during non-0VAC points and release it at 0VAC points to make for a constant voltage. This turns horrible-PF devices like HVACs from 0.2-0.3 to near 1.0. Electric Utility companies in the US like businesses to have a PF close to 1.0 an reward businesses with much better pricing (because they size for average use, not peak) and that often covers the cost [over time] of the PF correction device. These are more often seen in the 480VAC and higher world. Best wishes
I was just reading about power factor a few days ago, prompted when looking at the schematic for my Miller welder. It showed an PCF option so I delved into it. It was I think 4 x 200MFD run capacitors. There was a chart showing the amperage difference with and without. If I as welding all day I would be very interested as it indicated a fair reduction in power used.
that was one of the most informative and well written explanations of electrical power distribution in america as it is done today that I have ever seen. I'm a retired electronics tech and learned a couple of things and relearned a couple more that I had forgotten, thanks for the refresher course. :)
Power (kw) used by your welder is the same; just amperage in the lines feeding the welder is lower with pf correction. PF correction caps put voltage and current closer in phase. When 100% in phase, pf = 1. PF correction in residential systems is usually not an issue because you are not billed or penalized for power factors less than 1. With better pf, you may be able to get by with smaller gauge wiring, ie, if your welder is a long way from your service panel, but your electric bill is not likely to change. However, industry uses considerable energy, and pf less than 1 causes higher line losses for the power company. Power company will bill industry at higher rates for poor pf to cover these losses.@@stephensarkany3577
Edison was very concerned about safety and 110V is a little bit safer than 220 so far as electrical shock is concerned. 220V allows using smaller wire and thus its cheaper to implement. I noticed this right away when I bought an extension cord in the Philippines. It's much more flexible than one from the US.
Edison played the safety card because he wanted to use DC power. Not AC. Edison shocked his employees (as motivation and to wake them up), had a wire run around the shop that was used as pest control (not exactly something safe), he also electrocuted dogs to death to demonstrate the deadly unsafe power of AC current & an Elephant that was said to be bad/out of control after it attacked & I believe killed someone that abused the pour already often abused elephant. Edison got to showcase his motion picture recording device. Along with this. The thing he tried to use his patents to basically be the film industry. But, a judge ruled against him and Hollywood was born. (Or something like that.) I wouldn't say he was big on safety. As much as I'd say he was trying to turn the public on the much better competition. He was a businessman. If anyone today tried a fraction of the things he did the public would shun him so fast. People would be sending smoke signals before using the Edison Phone, camera, light bulb, or any other thing with his name on it.
Just a tip but you need a body mic (or a better recording location) to reduce the harsh echo of the room and better lighting (you're being lit from below). You tube has videos to fix these issues. Cheap things like moving blankets hung while recording will soften the sound and lighting. Great video and topic. ❤
I ask this question when I start covering electrical power systems for aircraft. The genesis is the light bulb. Aircraft use 400Hz to reduce the number of copper turns of the generators and reduce the size of cores in transformers.. On large transport aircraft with long cable runs, Aluminum is used and spiced with Copper for the generator feeders and the feeds into the distribution centers. On most commercial aircraft DC voltage is a higher 28 vs 12 on cars, similar purpose to save weight by making the wire size smaller because of reduced current. So happy to find your videos.
@@joeozzie1 yes because for a given voltage, the magnetic flux proportional to volt-seconds, is reduced at higher frequenies requiring less core. Also since reactance is proportional to frequency, the number of turns can be reduced while keeping magnitizing current the same. The reduced number of turns also reduces resistance. Taken to the limit you end up with switch mode power supplies that use very small transformers operating at hundreds of kilocycles or even into the low MHz.
The US actually uses 240V extensively within the home. The 120V service is center-tapped off a 240V phase on the street. Each side is 120V but on your electric panel, you can draw 240V. Electric baseboard heaters are generally wired to 240V in this manner and you could easily wire a 240V plug if you wished. Using 120V for most outlets is far safer than 240V. Countless lives have been saved in North America because of the power outlet voltage, yet the center-tapped power supply offers 240V when you need it - such as with baseboard heaters. It’s actually genius.
@@MrDodgedollaris that why only 6% of fires in the US are electrical and the UK is 12%? Fusing in the plug is not nearly as safe as central fusing or breakers, and much less safe than the gfci system used in the US for high risk circuits. Maybe it’s the little plastic covers that block the outlet holes you think are so safe? The US and most of the works solved that by having prongs that are much smaller than a toddlers fingers!
Fantastic presentation of some important power history. I'm a retired EE/CS and while very well read on early AC power as well as some on Edison's DC, the use of +/-110 V by Edison as a means of copper savings was not known to me. Impressive research, and a most enjoyable presentation. I'm looking forward to your book and thank you for your outstanding work. One piece of history I'd love to see you do is Edison's early attempt to use earth as neutral, and the resulting shocking from step voltage potential. Another would be the insane WYE multiple earth grounding practice which was used to protect motors, but violates transformer isolation and thus injects massive neutral current through the earth as well as creating a problem similar to but lower than Edison's earth as neutral.. Zipse's work is a good starting point. Thanks again for all your outstanding presentations. I'm a big fan. Bruce
@@foureyedchick life is a bit more complicated, both Tesla and Edison did things that today we would consider dishonest and Edison did invent stuff quite a bit
@@brianm1916 And what are YOU? A meddler in somebody else's conversation? What are you? His lawyer? His gay lover? What should your name be changed to? "Brian M --> Brian Misogynist"
The more popular line would have "Less Resistance as load" and "More Current flow" as a result of more lamps attached. See Ohm's law: V=I*R where V is Voltage, I is current, R is resistance. More lamps in parallel would lower the overall resistance, and cause more current to flow. Now if you discuss the feeder cables, the more popular line (might) be longer, due to more customers spread out. In that case the feeder cable would have more resistance, and hence there would be more voltage drop in the line.
It depends how Edison noticed that there was more load on the more popular line. As the electrical resistance goes down the mechanical resistance to turn the generator goes up. If you are at the power plant measuring the power it takes to drive the generators you can say that the more popular line has more resistance.
@@tapioleva9851 But it doesn't. If we're talking about electrical resistance -- which we are -- it goes *_down_* when a greater load is applied. (i.e., the video is wrong and "hsailer" is right.) Yes, it takes more torque to turn a generator that is powering a heavier load, but that is not "resistance" in any proper sense.
@hsailer Thank you for saving me the time of commenting the same thing. The only way more light bulbs add more resistance is if they are wired in series. Adding more resistors (bulbs) in parallel only lowers the overall resistance of the circuit - even regardless of the length of each line. For instance, one light bulb added 50 miles away might not lower the resistance of the circuit as much as it would if added 10 feet away (due to the inherent resistance of the 100 miles of wire), but assuming that 100 miles of wire was already there and the resistance between them at the ends was effectively infinite, dropping in a 120 ohm bulb would drop that infinite ohm value down to 120 ohms - therefore a reduction in resistance overall, but the wire may look like a 240 ohm resistor in series with the 120 ohm bulb. Either way, it would be like having a 360 ohm resistor instead of a 120 ohm resistor, and that is still smaller than infinite.
"the feeder cable would have more resistance". Voltage drop is what causes the lights to dim. No matter how long or short the line is the voltage drop increases as the current increases. While the length of the feeder will affect the voltage drop as it increases, the resistance of a feeder is low enough that current increases will affect it more than length.
Parabéns pela ótima aula. Sou engenheiro eletricista formado a 40 anos e está é a primeira vez que alguém consegue explicar porque 110 ou 220 volts de forma tão didática.
Great job as always. I remember my brother trying to explain some of this to me years ago and my eyes glazed over and I passed out. You actually made it interesting!
You start out talking about Edison's dynamo as DC, which is true. The system that we use today is AC. You even talked about the transformer with regard to Edison's system. It is physically impossible to have a DC transformer. That is one of the reasons that AC became preferred, it was impossible to transmit power over great distances as the voltage dropped quickly over the lines. Edison's plan was to put a generator on every block.
A good presentation concerning the history of modern electrification of the US and world I would like add the following. December of 1887, Tesla filed for seven U.S. patents in the field of polyphase AC motors and power transmission. These comprised a complete system of generators, transformers, transmission lines, motors and lighting the German system is based on Tesla's alternating current system which went on to illuminated 1893 World's Columbian Exposition in Chicago.
glad you brought that up, no one remembers that edison held back the country from going electric because he fought tesla tooth and nail because he is a fucking egomaniac and could not accept the truth and the real genius behind modern elictrical power, i blame edison for tesla dying broke
@@jimmieroan9881 - I think Tesla broke himself with his fixation on Tesla coils and wireless energy transmission. He built the hugely expensive Colorado Springs lab shot lightning bolts around but never created any marketable products from it. The Wardencliffe Tower on Long Island was the final straw and even his most ardent investors had to say no, we are going to build a system to send electricity through the air for free. Great creative thinker and inventor but no practical engineering and economic sense.
Almost all houses in the US have 220-240 volt and most higher draw equipment, electric water heaters, electric ranges, clothes driers, and are 220-240 volt in most US homes. It comes into the house as two 110-120 volt to get the 220-240 volt, but most outlets use only one or the other side so have 110-120 volt for most electric stuff. It is crszy so many people say the US is 110-120 volt when we use both.
Like here Finland one phase is 230V 50Hz and between phases 400V (3 phase) At 230v the advantage is that thinner cable can be used relative to the load than the 120V system uses.
The first use of the iron skeleton frame building method was use for Ditherington Flax Mill in Shropshire, England in 1797. This method quickly spread, resulting in it being used to construct Skyscrapers in New York.
We do use 220 (240v) That's our single-phase standard. We just split it into two legs balanced around ground (center tap on transformer tied to ground/neutral) for light load resi.
Wow, Kathy, this was extremely informative on so many different levels. You touched on it, kind of, but even with 220, we are still 110! It’s just that the other leg is inverted to the main leg so that they sum to 220.
@@xiaodingjones1554 I was looking for someone to correct her about phase separation angle and adding phases. Single phase with center tapped secondary ground/neutral. The legs Y-me referring to are these opposite sides of a single phase.
@@xiaodingjones1554 In the US we have split phase, so the phase of the two legs are 180 degrees apart (technically in relation to neutral, but that gets a little more complicated to explain)…
US standard voltage today is 120. In most utilities it’s 120 +/- 5%. Standard residential is 120/240 single phase with neutral. Three phase is either three wire with neutral 120/208 Y, 240 delta or 277/480 Y with neutral. ST substation engineer.
@@paulsawczyc5019 this video seemed to suggest that 2-phase is still a thing, which is actually a rare find in some of the older u.s. cities much like your Con Edison DC motor.
Literally power transmission is 240V single split phase in america. It’s only when you get to the lines that service a row of houses, after the transformer with a center tap on the low voltage side, do you get two 180 degree phases of 120V from a single phase high voltage supply. It’s why every house in America has 240V available at the breaker box.
Your Kitchen Range uses 240V, Dryer 240V, Water Heater 240V Air conditioner 240V unless you use gas and prop windows open you do have 120 and 240 in the USA and have for many years. OHMs LAW can explain this all very well.
@@chrisowen2925 Ohms law does NOT explain it. In fact it is NOTHING to do with it. It is to do with the voltage across the windings of coils on the secondary side of the transformer. It's to do with the formula for the voltage output of the transformer which is: Vout = Vin.(N2/N1) Where N2 is the number of turns on the secondary side, and N1 is the number of turns on the primary side. It is also to do with Faraday's law of electromagnetic induction and mutual inductance. Nothing there about Ohms law whatsoever.
@@deang5622 - Ohms Law does have some effect, note that the AC Power is rated at 120 v & 240 v, however when you look at motor nameplates most at rated at 115v & 230 v. The reason is voltage drop which can be calculated using Ohms law for AC RMS voltage/current. The reason for the 5 v difference is that AC motor companies allow for a 5% drop in line voltage due to wiring resistance and transformer winding resistance.
Actually...just about every home in the US has 240V. They just break it down into 2 legs of 120V for lower current uses. The whole point of higher voltage is less current for the same amount of power. POWER (W) = Volts (V) X Current (A). Current is what heats up wires. For a given amount of power needed, you can safely use a smaller gauge of wire with a higher voltage. Saves Copper...saves Money. (Then there's 3 phase...but that's another story...:-))
She went through book history rather than the engineering and logics. It's why letting the Liberal Arts portion of A University teach Applied Science is not a thought out idea.
@@AncientWisdom222 Think of it this way: Countries with big copper mines "somehow" often found 120v more agreeable. Countries that had to import copper found that 240v was quite good.
In Europe, there were many locations that still had 110V up until the sixties. There was made a large push here to change that to 220V. Up until now, there is still 3phase 230V in Belgium and Norway from which you can still use a floating neutral to make ~110V. That will actually cause a lot of problems for home chargers here, as the current will be a lot higher for the same power.
the US uses a similar system as norway. but a split 1 phase system rather than 3 phase. so in actuality every house in the USA is supplied with 240V, it's just center tapped so that 120v would not need to be phased out. EV, washing machine and hvac are examples of things that utilize 240v in the us.
I grew up in a house in Auckland NZ that had 240 volts DC reticulation. In 1953 this was changed to 240 VAC. The house was very old and the cabling was rubber insulated running through exposed steel conduit down to the various very clunky switches made for DC. The problem was that for 240 DC you only need to insulate for 240 volts with a margin. For 240 VAC you have to insulate for peak voltage which is 240 X 1.414 = 340 volts. Subsequently the rubber insulation failed livening the exposed conduits and we started getting nasty shocks. The landlord would not fix the problem so we ended up leaving the house.
Wow that's really interesting, thanks Colin. I didn't realise DC was used up to 1953! What part of Auckland? Where was the power station? Devonport? I imagine it had to be fairly close by to minimise line loss. Cheers.
@@peterhall9603 King's Wharf had a DC substation up 'til the '80's - some lower Queen Street buildings had DC powered elevators until then. The DC from King's Wharf also powered the trolley buses. Those trolley buses were withdrawn when the King's Wharf substation was closed.
@@laurencetucker9967 Thanks Laurence. I knew that the trolleys were DC powered but assumed it was a large AC to DC (probably rotary) converter somewhere. I remember the DC elevators too but hadn't thought about how they were powered. Cheers.
Very interesting lecture! In Dutch we have a name for this phenomenon: De wet van de remmende voorsprong, the Law of inhibiting head starts. Those who implement something first do not get to incorporate later improvements that are incompatible with the earlier version.
English needs a punchy phrase like that for this phenomenon. It is not quite the same as "technological lockin", which locks the whole world into (sometimes inferior) technology choices. Both are common.
120v going from to 230v is not a step up in technology. If you wire a broadcast tower for lighting in the pre-strobe days the FAA required that beacons on the tower consist of two 620 watt incandescent lamps. If your tower was tall enough you may need four or five beacons. In my now remote youth I asked my supervisor why are these lamps 120v lamps used on the tower instead of 240v lamps. He said "240v lamps only have half the expected service life." Europeans spent their money on tungsten rather than copper. Besides you don't want to do this any more than is necessary:ua-cam.com/video/f1BgzIZRfT8/v-deo.html Not that I ever did.
My house built in 1910 originally only had 4 circuits at 110v. I always wondered if it was missing a “leg” for not having 220. Thank you for the video explaining that it was normal to only have one hot and neutral at the time for residential buildings!
I lived in a house (Pittsburgh,PA,USA) that only had 4 110v (fused) circuits in the 1990s! My dryer, furnace and water heater were all gas, luckily. But doing something "crazy" like using the Microwave and say, the toaster or coffee maker at the same time weren't gonna work!
It's not normal to have multi-phase in British homes, but we have plugs with freaking massive pins for carrying 13 Amps, and that at 240 Volts. (3kW from any socket!) They were supposedly invented for our tea kettles. Full-size cookers have to be wired in, but we can just plug in anything else; I've never heard of a gas dryer before. ;) Even some heating can be done with plug-in devices, but sadly, standards have slipped to the point where the fire department recommends you never use more than 2/3 of the available power from a socket.
@@eekee6034 Lots of people in Pittsburgh have gas appliances as this area is sort of a "Saudi Arabia" of Natural gas. It's cheaper to use gas than electricity for anything that "heats" for this reason. Of course gas dryers do use electricity for the motor. It's the heat that comes from using gas.
Amazing description of all of how this all works! I knew about Tesla(Westinghouse) and Edison. Describing the reason for the country's uses of the different types of power that are used was amazing. I didn't know that it was more expensive for America to use 110, LOL! And now I know the reason why we stayed that way too! Thank you for such a great answer to such an interesting question!
Awesome video! very informative about the history of electricity transformation/generation! One tiny gripe is that in the US most residential supplies are 240V 1 phase, not 2 phases 180 degrees out of phase with each other. The difference that can be confusing is that distribution side of the transformer utilizes 2 wires (1 line and 1 neutral wire going into the transformer) and the residencies side of transformer has 3 wires. The third wire is called a center tap and it literally taps into the center of the transformer coil supplying power to the residence. That's where the half voltage value comes from (half of the transformer coil turns being utilized for some loads). This is called a split phase supply and is 240v/120v from one single phase. The neutral conductor for the residence is that center tap and that sometimes causes confusion since there is no voltage grater than 120v to neutral (some utilities supply split phase with higher or lower line to line voltage but it's the same concept). Just remember that the utilities' neutral wire and the residencies' neutral wire are absolutely not at the same potential in this scenario.
Right. the transformer out there is really a center tap on the secondary side. the primary is generally thousands of volts whose potential varies depending upon distribution. Primary/secondary are completely isolated thus the secondary could be all kindsa configurations.
I love these videos! Kathy is the only presenter that gives both technical and historical information. As shown in her videos, politics and human interactions produce not only significant results, or they ruin things for years. Gee, I thought scientists were only interested in the truth.
Thanks Kathy. I hope you also teach about Nicola Tesla, who provided importantly to Edison's DC generator advances, but was badly treated and not paid for his efforts as Edison had promised. Tesla was a brilliant, generous man whose story is unfortunately told. In fact, he is the reason for AC! Westinghouse recognized and helped Tesla develop much of the work resulting in the AC systems which enabled so many to benefit, because it's so superior to use over long distances. In fact, Tesla's work enabled Westinghouse to win a competition with Edison to light the exposition.
You’ve crafted a decent story, and you even got some points correct like needing higher voltages to span longer distances. Please read NFPA 70E. 110-120 VAC is the desired voltages for plugs that the majority of people shall plug the majority of devices into frequently. The average resistance of the human body is about 110-120 ohms, so getting shocked by 110-120 VAC around 1 A is minimizes both injury and death. The reason I mentioned the NFPA reference is that it gives people more information to safely work with electricity.
A great video. I love physics and I love history. I see by some of the comments one person already made a comment concerning your error of more lighting filaments being more resistance which is exactly backwards but what astounds me is that you were able to mention the whole thing concerning AC without mentioning Nikola Tesla. And the reason the generators were in the basement before Nikola Tesla's invention was Thomas Edison was a DC man. DC cannot be transmitted over long distances so each building had to have a generator in the basement.
DC can easily be transmitted over long distances and it is very good for that, because the DC current lacks skin effect in the conductors. That's one reason why many of the high power links are realized with HVDC. In the early days the problem with DC was voltage conversion as it can't be done with traditional iron core transformers like it is done with AC. Anyway higher voltage is required for minimizing the transmission losses. Therefore AC was chosen instead of DC in most places.
@@laakeri84 Yep. And for a given size of conductor, the losses increase as the frequency increases. Higher voltage means lower current - which reduces the I squared R loss. For example, a 120 Volt line carrying 100 amps will have 4 times the resistive losses as a 240 volt line carrying 50 amps.
Thank you. You do not appear to mention that the standard today in north America for domestic electrical supply is now 120 / 240 volts, 60 Hz. at typically 200 Amps per house.
New/nearly new housing might be built with 200 Amps per single unit, but half the detached single family residences in North America are old enough to have 100 Amps (1970's) or only 60 Amps from the pole (like my previous home built in 1950). Updating them to handle a 40 Amp Type 2 EV charger involves fatter wire from the street, a new breaker box, etc. Also new supply transformers if everybody in an area upgraded in the short time period proposed for EV adoption. It's not as expensive as the new EV they want us to afford, but it's still a couple of months' salary per household to upgrade the supply in an older area. (edit: plus higher fire insurance rate because of all the people who think they can upgrade power themselves by just buying a new main breaker and adding a sub-panel...)
130V has been used as well in Europe (up to 1958 in my case). That time they decided to pass nationwide to 220V while swapping every appliance to the new voltage (and sometimes by replacing the appliance or providing an autotransformer 130/220). Later the standard became 230V for mass production, UK passed from 240V to 230V and the continent from 220 to 230.
In the UK, the official voltage is 230V with a wide variance. If you put a volt meter across the mains, you will find that in reality it is a lot closer to 240V than 230V.
I know that UK is not part of EU any more, but when EU decided to have 230 V they also narrowed the max voltage to 6 % and min 10 %. So the max voltage is 244 V. Before it was 220 V for most countries and the tolerance was +/- 10 % which gives max. Voltage 242 V.
More lamps in parallel results in less resistance, not more. The power reduction with more lamps was due to increaed current draw which the dynamo and/or wiring could not support at 100%.
Before AC was used, streetlamps were even fabricated for voltages ranging from 100 V to 110 V. You would use lower voltage lamps near the end of the power line where the voltage was lower.
Only the heating element in a domestic dryer required 220 volts, the rest of the dryer is 110 volts. That makes it easier to also use the same base model for a gas dryer.
First, it is the other way around. You sit down, do the math, plan your specifications and device. AFTER that, the heating element is chosen/constructed/wound up. Second: heating elements are resistive consumers. purely ohmic resistances. The selection criterion for two or three-phase electricity feed is based purely on the required heat output, which is proportional to the needed current strength, which as well determines the needed line(electrical wire) cross-section. With phase-shifted alternating current it is also possible to use simpler and cheaper motors for the drum. With a star/triangle (YΔ) circuit you also get the possibility of easy temperature adjustment in the heater(think at a time before 1920! :) ), setting of the motor characteristics or easy power adjustment. Trivia: Just do the math. Basic American Outlet, 110V x 15A = 1650W (vs. x2 or x3 or 1/3 with the same breaker/wire specification). My (German) transportable fan heater has more heating capacity:)
Dryers, irons etc all are over 2kW in Europe. To deliver the same power twice the amps must be transported. Standard wiring would be thicker and too expensive.
@@Be-Es---___ I really can't understand why people write BS or waste our and their time with it?! In times of google and wikis. A simple search proves your first sentence wrong. A current has to be transported anyway and where comes that strange "the same power twice" from? The STANDARD determines which conductor cross-section is used. If your gibberish really means that a standard compliant line from plug to device, let's say 10A vs 16A = 1,5mm^2 vs 2,5mm^2 has any relevance in contrast to the device cost ... then I'll take you as a stand up comedian. A bad one ... Details: "To deliver the same power twice the amps must be transported." ... WTF? The same ... or twice? BS! ... its simply 2 * (V * I) if TWICE the power was meant, which translates for normal people as: The product of the two factors voltage and current have to be the double amount as before. "Dryers, irons etc all are over 2kW in Europe." ... amazon says BS "Standard wiring would be thicker and too expensive." ... Talking about "standard" wiring for any iron tells the knowledge of the writer. The "standard" there is heat-resistant cable with the appropriate conductor cross-section determined by the device protection
@@dieSpinnt Having lived and/or worked in many 240V countries , I will say there are plenty of common electric appliances which are fairly high wattage. A typical electric kettle (*very* common item in tea drinking countries) can be up to 3KW. Dryers not so much ... but that's partly down to Energy Star programs. In the UK, wall outlets are usually rated at 13Amps - at 240V that's 3.1Kw - and we don't have special high-amperage circuits. So things like power tools etc are often designed to draw more power. Also very common in the UK are immersion heaters for water - and those are definitely 3Kw because I used to replace the element on mine routinely as we lived in a hard-water region. Bart Sw's comment on "twice the amps" is correct, just badly phrased. To run a 3Kw heater from a 110 outlet, you need to draw over 27Amps and most US outlets aren't rated for that. So yes - keeping power constant ("the same power") and halving the voltage, you need "twice the amps". Also, there's another major difference in the UK when I lived there - and one which has caught me out here in the US repeatedly. You NEVER run ceiling lights and wall outlets from the same physical breaker/loop. The ceiling light loops were each protected by a 5Amp fuse/breaker. That let you run up to 12 100W Bulbs per loop (and use less copper).
I was a little surprised by you mentioning transforming voltages in distribution systems before you introduced AC with Westinghouse at the Chicago Fair. The only real transformation option for DC electricity pre AC would have been highly inefficient motor generator units.
It's 110V vs. 220V (past) and now 120V vs. 240V present day. The voltage was slightliy increased across the world. And there is 240V in every house in the USA. It's juat a matter of how you are connecting the local sockets.
Hi In the UK Joseph Swan is considered to have preceded Edison to develop a working lightbulb. His invention was based on a carbon filament rather than platinum by Edison. Many scientists around the world helped Swan and Edison improve the operating life.
Swan was before Edison before him there was a french man a Russian and a German that invited parts there is zero reason to think Edison invited anything and you have a bad electric system because of him.
@@EVPaddy Yes then a SOB steals it and claims he did the work. An episode on the USA patient system before 1958 would highlight that china's not the biggest IP thief even
Here in Spain, 110-120V was still around in some regions in the 80s, and in some rural areas, it continued into the early 2000s. If I understand correctly the switch started sometime in the 50s, so that means people would have had to use step-up/step-down transformers for up to 50 years, to be able to use their 110V devices on 220V, or their 220V devices in 110V, depending on the case. I never saw 110V on the lines myself (I'm 37), but my grandparents still have devices that are 110V, which were made sometime in the 40s or 50s, and they have a couple step-down transformers for use with those devices, when they need them. In the case of my grandfather, it's a drill press, with a relatively powerful drill, which would be too expensive to replace for the little work he does as a hobby. In the case of my grandmother, it's a coffee grinder which she uses to grind sugar for use in baking, because nothing else she has tried leaves the sugar as fine and uniform.
Actually most AC line voltage in USA is not 120 v and 240 v, and 240 v at 60 Hz is delivered to every household with 3 wires instead of 2 so that the center tap of the output winding of the transformer can deliver either 120 v or 240 v to the appliances. Lights and most AC outlets are 120v and electricians try to balance the phases of the 240 v winding such that the neutral center tap carries little current. Electric hot water heaters, electric ranges, electric clothes dryers and central air conditioners are all wired with 240 v and you will notice that those devices have double breakers in the power breaker box so they get power from both phases of the AC secondary transformer winding.
I think this might be the reason why my country (Brazil) uses both voltages. Parts of the southern region uses 220v and the major cities use 110v. It is a big problem for appliances when traveling, in my home state you can find both, and in my house we have both, usually it's used for appliances which uses more potency such as clothing dryers. I believe parts of our electric grid were built from both British and American investments in the past, will have to look up now
Few regions in brazil still uses 110V, most regions nowadays moved to 127V, that's why we don't see electrical equipment classified as 110V anymore, they are either classified as 127V or 220V or fullrange which accept any voltage between 100-240V. In the state where I live the only available voltages for houses are 220V and 380V.
USA has both 120V/240V and has both in every home. Most homes just reserve the 240V to big appliances, but any of the circuits can be changed to 240V if desired.
In the US the electricity is primarily distributed as split phase. It splits a single phase at the transformer and the neutral is generated it the mid point of the split phase transformer. So the two 120 volt wires that come in your house are in phase. A single phase. The confusion largely comes from probe placement with an oscilloscope. We actually have 240 split phase service in most of the US
The two 120V half-phases are 180° out of phase because they are the created from each hot lead of the 240V. The neutral of the two half-phases is created by physically putting a tap in the middle of output circuit with the same number of windings from the neutral to each leg of the 240V. A single 240V phase is split to create two 120V. Hence the name split phase. If you really believe the two 120V half-phases are in phase explain how a 240V curcuit breaker works. If the hot leads of both 120V circuits were in phase you would have 0V between the two half-phases. Get some extensions cords and test the receptacles in different areas of the house. You'll get 0V for circuits on the same half-phase and 240V for circuits on different half-phases. .
@@blueoval250 120 volts nominal voltage to earth/ground . . . not line to line - as that would be reflected at the full secondary voltage of 240 , whereas in Europe , Asia and parts of South America - domestic power is actually derived from a 3-phase power transformer with the secondary windings connected or terminated in a WYE configuration , with each secondary phase winding at a nominal voltage potential of 240 volts A.C. 50~ Hz . . . and the line to line or phase to phase voltage potential at a nominal 415 volts at 50~Hz In the United States , Canada , Mexico and parts of the Caribbean Islands - the Single-Phase or 'Split-Phase' 3-Wire Transformer Secondary with the full voltage across the entire winding being at a nominal 240 Volts A.C. at 60~Hz and center-tapped to Earth/Ground (Neutral-Point) where each half of this secondary is now at no more than half of the full voltage potential to earth/ground and is also used as a circuit-ground or common/neutral conductor in order to carry the unbalanced or neutral-currents back to the power source (transformer secondary winding) where this circuit ground or common/neutral has been derived from in the schematic . . . In a perfectly balanced 120/240-Volt 3-wire system - no current would be flowing on the common/neutral conductor , as both 120 volt loads on each end of the transformer secondary winding would then be operating in series across the entire 240-volt transformer secondary - since each opposite end of the 240-Volt secondary winding are effectively at opposite polarities from each other and the phase shift would then be at a 180-degree difference from each other , whereas the voltage potential across any one of these 'legs' (as they are called in the electrical trade) will not be anymore than half of the full voltage potential across the entire transformer secondary winding - the main reasons as to why this system is still referenced to as a SINGLE-PHASE system is due to the number of transformer windings on the PRIMARY SIDE of the transformer , along with how many primary power lines it is associated with in contrast to a bank of two or three transformers on a pole supplying a 3-phase service to a property or a structure - where at least 2 or 3 primary power lines are going to be used (as in that of a 240-volt open-delta 3-phase, 4-wire configuration that uses only two transformers and not three) . . . Also bear in mind that a 120/240-volt single-phase 3-wire electrical service could and are often also derived from the same bank of transformers so connected in a 240-volt delta configuration - as the 208-volt high-leg would then be omitted from the scenario . . . Such as what would be found in an area where both commercial premises and residential premises are nearby and are sharing the same banks of power transformers . . . as what would be utilized for 240-volt services . . . Not to be confused with 120/208 WYE 3-Phase - 4-Wire service that would then need an entirely separate bank of transformers , since the phase-angles on all three phases would then be 120-degrees apart and each leg or phase would also have a multiplier of 1.732 for phase to phase voltage or by calculating with the square-root of 3 . . .
This story is great! Unfortunately for Edison, we see that he was not as big a genius as school textbooks say. A lot of different people of different nationalities have made bigger inventions than he has in the electricity stuff.
Oh, come now; let's get a grip. Edison's genius was not restricted to things electrical. His invention ranged across a wide array of explorations. I don't know what school textbooks say, but Edison's abilities were without question formidable and outstanding. We can also say that full-heartedly without minimizing the fact that many people in many places are always behind any large-scale developments and advances. No one person ever does it all, even in a single discipline. There's plenty of room to recognize everyone's contributions. The big mistake is to try to find "the biggest", "the best", "the most" among individuals. Each person adds a layer into a process, that layer forming a foundation for later ones, and itself resting upon layers preceding, and sometimes side by side with concurrent developments, all of which are building blocks. The overall picture is just as amazing as each individual piece. Competitions are for the weak and insecure. Contributions are where the muscle and brains are.
110V system is outdated for North America. During my last years trip to Canada, I noticed that they have both 220V and 110V connections to homes! 220V for car charging, cloths dryer and other high powered appliances, and 110V for others. It would be simpler with one system- 220V connection to homes, like how the majority of the world’s homes are wired.
You make an amazing number of factual connections in your videos and you’re engaging. Please keep em coming. Subscribed! Please don’t be afraid to show equations (even if you don’t dig too deep into them). I think you have a lot of folks watching that would appreciate it.
Until the 1930s there was a dizzying array of different types of power supply depending on where you lived. It might be AC or DC, the nominal voltage might be anywhere between 200 and 250V and on AC system the frequency might be 25, 50 or 60 Hz. This was because power was supplied by local generators, often owned by the municipal authority. However during the 1930s construction of the National Grid began and that distributed power at 50 Hz 3-phase AC. Local distribution was at 230V. Because construction of the Grid was delayed by WW2 it wasn't until the 1950s that all areas of the country were connected to the grid and some local areas continued to have these non-standard supplies right up to the early 1960s. After WW2 the nominal voltage of local distribution was raised to 240V, but more recently it was notionally reduced back to 230V +/- 10%, but in practice supplies are usually still around 240V.
Very interesting video. Small correction to the multiplier of 1.72 you mentioned at 12:45: The relationship between phase-to-phase voltage and phase-to-neutral voltage on a three phase system is the square root of 3 or approximately 1.732. 120 x 1.732 = 207.84 so that voltage is called 208/120.
the stinger leg 120/240 volt systems are delta connected and the 120/208 volt are connected wye. You get the stinger leg from three phase120/240 volt delta with a center tapped neutral. In San Francisco, the stinger leg was color coded purple or orange.
We DO use 220v, in fact in most neighborhoods the poles and ground systems carry 3 sets of 220v and we just use a trick to make it 120v. The power is distributed as 220/240v! Unlike most places that have 240v direct to outlets the US also has a grid that grounds out uneven soil charges to a distance. You can't do that reliably with 220/240v-only systems.
Good point, and I was going to get into the whole split phase thing and then I realized it’s just too complicated and in truth what we get in our plugs is still around 120 V
@@Kathy_Loves_Physics Haha, lets confuse everyone and sneak in 3 phase 400 cycle power. Aircraft stuff! I worked as a Field Engineer for GE decades ago and flew all over the planet. Of the many gas turbine and steam turbine driven generators, almost all I installed or worked on were 3 phase 60 cycle wye connected that output 13,800 volts. They ran at 3600, 1800, or 1200 rpm depending on if they had 2 magnetic poles, 4, or 6 as used on many marine 1200 rpm generators. Nearing age 70, I still have more than a dozen working generators in my workshop. It's a hobby.
Fantastic video, Kathy! I really appreciate the amount of time and research you put in your work. It's always worth waiting for you, so I'll always like the video before even watching it! :D wish you all the best!
Fascinating! What I loved most about this video is that I got a bunch of interesting questions answered, which I didn't know had. Also excellent narration.
I love your enthusiasm Kathy, I've often wondered about this. Could you look at the development of underground transmission lines, and the move towards DC for long distance transmission?
i always thought that we were worried that 220 volts was too unsafe. although there's some argued that 220v was more safe because it would be more likely to throw you off of it. whereas 120 volts was more likely to keep your hand clinched and causing you to not be able to become detached from the source
is that true? that's really interesting . i have zero understanding of how electricity works and i am terrified of it after almost electrocuting myself as a child . i live in Germany now and have this apparently incorrect idea of how dangerous 220 is ?
@@siriosstar4789 220-240 tends to knock you back. As stated above, 120, if you’re grounded properly, will literally grab a hold of you and curl your fingers around whatever you’re holding, making it next to impossible to let go. That actually happened to me once, and I was electrocuted for approximately eight seconds, before my boss came over and pushed the ladder out from under me. On Friday, I was working on some lights in a car dealership, and as usual, I wasn’t being careful, and I got hit with 277 V. That hurts. But I’ve been hit by 277 many times. Most of us electricians are too lazy to go turn the power off. And besides, panel schedules are never correct. You could waste more time trying to find the correct breaker than repairing the actual light. It’s like a horse. You get bucked off, you get back on again.
Quite simplified explanation for general public. Electric power generation, transmission and distribution is trillions of dollars industry in the world. It can get very complex when you add billing meters and trading generated electricity. Good job and thank you for your efforts.
In the European Union the voltage is now standardised at 230v 50Hz. ( it used to be anything between 210v to 240v depending on what part of Europe you lived in.)
In your graphic there at 2:40 you’ve got it backwards. You’re showing lights in parallel, and the more loads you put in parallel the less resistance there is in the circuit, thus the more load the generator sees. That’ll tax the capacity of the generator, drawing more current and potentially bring down its voltage a bit. You brought up some interesting historical points. I don’t know why you’d not mention Tesla, and his and Edison’s battle over AC v DC.
Yep, I noticed that was backwards immediately. The more "popular side" as she puts it has LESS RESISTANCE because the lights are in parallel. I find it amazing that at least 2 commenters claim to be electrical engineers and apparently didn't notice the mistake. It really bothers me when people talk about electricity and get things wrong. She did have the "less light" part correct, since the heavier load will bring down the voltage. But at 5:00, now she's talking about transformers. Transformers don't work with DC. So she's mixing up Edison with Tesla there. I don't think Edison used transformers in his electrical distribution system.
Only commenting on the second paragraph. That story is fascinating and should have its own video. We were shown one i electrician school in Denmark but since it’s in Danish an English version should be made.
@@Hyxtryx you did have DC transformer also, but they are more complicated. Back then it was an electric motor coupled electric generator. In other word, not an efficient transformer. There is a reason that AC gained traction.
I am very impressed at how you can gain all this history and just explain it to us with reading it all from cards! You love this history and it show. Thank you for the wonderful history lesion's and facts of our heritage here in the US.
🇬🇧As a 58 year old electrician, I thoroughly enjoyed this Thankyou. Amazing that due to the development of ultra high voltage solid state rectification, DC is now starting to be used for extremely long distance transmission, in some cases over a million volts DC. Search UHVDC transmission…….😊
Not starting , HVDC at 500,000 Volts , 2 wire has been going from The Dalles , Oregon to LA , California for over 50 years! I wish English majors will stop writing books on Edison repeating that DC cant be transmitted long distance obsolete information !
I'm an electrical engineer. 20 years ago i asked the same question to my electrical machines profesor...that period when The USA selected 110 Vac was a time of paranoia and the US Gov thought the Europeans would flood the US market with european made 220 Vac appliances and Motors. So they selected 110 so the Europeans had problems producing both voltages appliances. He told me îs only for economical reasons although 220 V had economical design advantages.
And Europe also mandated that all machinery used in construction run on 110V... WHY? Fewer Deaths. Far more people per capita outside the USA/Japan and other 110V countries die than those running on 110V. As for the conspiracy theory baloney... What a joke, USA runs on 240V for all appliances/machinery just like Europe does and only ~kitchen handheld junk runs on 110V. Do remember by 1920's most electrical equipment was being produced in the USA and exported to Europe... Do remember in this period, there WERE NO household appliances worth mentioning other than Kitchen appliances and a radio which runs on lower voltage anyways so it is moot 120V/240V. Every country/empire had HIGH tariffs at the time. Something that should return. There was FAR more progress then as there were FAR more companies working on improving products and therefore for FAR more ideas entering production.
BTW, houses as in residential locations, especially single family dwellings DO NOT get two phases of a three phase system. They use TWO legs of 120 (from a single winding distribution transformer) and are provided with a neutral (ground). The result is 120 either leg to ground (or neutral) and 240 leg to leg. The phase relationship between 120 and 240 in the home is "0" degrees.
That's the most detailed description I've heard so far. I knew it had to do with Edison's 110V light bulbs, but that was all I knew. It was not only voltage, but frequency. Westinghouse favored 60 cycles while Siemens favored 50 cycles, so countries which bought American Westinghouse equipment standardized on 60 cycles and countries which bought Siemens standardized on 50 cycles. Japan brought from both, so they have an interesting mix of 50 and 60 cycles. Of course we have a few pockets of 25 cycle power, used for railroad traction power. Safe Harbor Dam still has 2 25 cycle machines to generate power for Amtrak. BTW the railroad uses 440V to distribute power on at least some of their trackside lines. I often see 440V written on the crossarms of open-wire trackside lines. Now we've come full-circle and DC has come back into favor, at least for some high power transmission lines.
I lived in Korea for several years where most homes have a transformer to change the provided 220VAC to 110VAC. The transformer was also the circuit breaker pane. All the appliances I saw in the shops were 100-120VAC.
Korea probably picked up the standard from the US. But rather than centeally breaking the phase into 2x 110v, it was done innthe homes and premises. I'm curious, what about 3 phase, as used in factories? As a sideline, I work in Laos (a landlocked country between Thailand, Vietnam, zchina Cambodia and some others). Anyway the US Embassy rewired their buildings and part of that was to split the electricity phase into 2x120 (it may have been 2x115, I forget what the country ran on). It was expensive to do so, but meant that the staff can plug in their appliances without have to think about compatibility.
It is important to distinguish between RMS (or effective) voltage, and peak voltage when talking about AC. Your chart shown at 13:00 is not clear about what figure is being listed. The source for that chart in Wikipedia does not spell that out either. The number for the US (120V and 240V) are consistent with these figures being PEAK voltage. What is the difference? Peak voltage is just that: the maximum voltage in the Alternating current cycle. This is the voltage that the insulation on a lamp[ cord has to protect you against. The 'RMS' voltage is the equivalent DC voltage that would deliver the same power to a fixed load. It is less than the peak voltage (about .707x Vpeak). This makes sense. Most of the cycle the voltage is less that the peak, and drops to zero for an instant each cycle. Therefore, AC voltage is often expressed as a root mean square (RMS) value, written as V rms, because P=(V rms)exp2/R.
Absolutely correct. The peak voltage above or below the zero crossing point at 120VAC is 120 times 1.414 (or √2) is about 170V. One learns this in Alternating Current Theory AKA electrrical engineering 102.
Well, you got some parts correct. But most wrong. The first two lines are for three-phase systems and it is the live to neutral and the other number is the phase to phase number both still in RMS voltage (how would I know that? The conversion factor is 1.73 or (SQR(3)). The third line is the split-phase system with a 180-degree phase shift, still RMS. The other two lines are single phases at higher voltages. The peek voltage is actually 1.41 times the RMS voltage (SQR(2)) and the peek to peek voltage is two times that. So a 120V 60Hz AC is 169.7V peek and 339.4V peek-peek voltage.
120V and 240V are RMS voltages, not peak voltages. Pretty much any AC distribution voltage mentioned is RMS, not peak. If you look at a 120V outlet with an oscilloscope, you'll see it going +/- 170V peak or 340V peak to peak.
Great content by Kathy.. Thanks to youtube for suggesting me your channel. Keep doing great work. :) One suggestion you can show some important words/dates/milestone flowing on screen when you are on video, that would make this more interesting and catchy and this will go to larger audience.
America is way behind in utility power. In Greece everyone has 3 phase 380v in our homes including apartments. This means we have much more power available. Also with 220v all cables are thinner due to lower current draw. Excellent video. Subbed.
The problem is that Greece is small in land size and population size than the US, it's a little bit smaller than the US state of Florida. The US is ~9.8 million km2 and Greece is ~131,957 km2. Population of US is ~329.5m and Greeze is ~10.7m. We also industrialized fast and early on. All of that means that what it takes to change us to 220/440v is orders of magnitude more complex and expensive. There was supposedly a plan to switch us after WWII but by then our grid was massive and we had so much equipment running on 110/120 that it wasn't economically feasible. Speaking of WWII, it was far easier for most of Europe to modernize because they had to rebuild after the war. The US mainland was barely touched during the war beyond Pearl Harbor and a few other isolated incidents. It's also a common misconception that US homes and apartments are only 110/120. What we actually have, and a correction to the video, is what's known as "split phase" not two phase. Our houses are fed by a 2x120v hot lines and a neutral. The 2 hots are fed from each side of the output of the transformer and the neutral/ground is center tapped on the transformer. Measured voltage between L1 or L2 and N gives 120v and between L1 and L2 gives 240v. Appliances with high power needs such as ACs, ovens, dryers, furnaces, heaters, and big motors can be fed by 240v via a breaker that spans both bus bars in the panel. Industry here uses 3 phase. No real need to supply a home with 3 phase. Computers, TVs, phone chargers, and most other devices use low current and don't actually run on 120v will have transformers and switch mode power supplies that drop the voltage down to some low voltage DC anyway. To be fair, I wish we did switch when we could and I wish we would phase out our horrible plug sockets to something safer like the UK plugs but I think we're decades past when that was possible.
@@Kathy_Loves_Physics It is, but that is the dialectics of lead. In every industry and technology it takes a huge leap to overcome that... if not it were ecomically unreachable.
@@tookitogo that's not fully the point. The point is that we're one single country that's very large and industrialized very early and changing our electrical infrastructure over for a high voltage is needlessly expensive and would probably take half a century. It's just not worth it. Any device that would benefit from the higher voltage can be supplied by it because our houses are supplied with 240v. If a commercial or industrial facility needs high voltage or 3 phase they can get it. Our infrastructure has problems but the voltage delivered to our houses is hardly an issue. Side note - Texas has it's own grid and it's a disaster because it's horribly under-regulated by their utility board.
Great presentation on the history of electricity. Thank you for creating a comprehensive and understandable video. Without intending to be critical, I think the video would be enhanced if there was less hand and arm gesticulation.
I disagree. I wasn't even concious of it as I watched. I just got the general impression Kathy is speaking with a general degree of enthusiasm. It is important for any presenter to appear to have a genuine interest in what they are saying, or the whole presentation becomes mind-numbing, regardless of the topic. Kathy, I thick your style is fine, don't worry about it.
I have an alternate theory, centered around the relative wealth of the USA vs. just about everyone else. All things being equal, lower voltages are safer than higher, but lower voltages need much more copper, which the USA had plenty of. Also the USA was energy rich, whether it was coal or oil. This also removed any incentive to maximize efficiency, unlike in resource poor Europe. In a similar vein, 50hZ is slightly more efficient than 60hZ, with the disadvantage being the transformers and motors require more iron. But iron is cheaper than copper.
Some of this makes perfect sense on some. but huge assumptions on others, I love that no one brings up the fact that Edison was in patent courts as much as he was in labs, and many of "His" inventions were litigated. Similar to many other inventions at the time, and we know how much of a sport he was, see (the current wars and the stunts), etc. I get the definite feeling that like a certain fruit named "inventor" (SJ) a great salesman rather than great inventor would be more fitting, and like our modern hero, technologies and technological innovation drove the "invention" (I know they would never get that rich selling the computers). I think history does a great injustice to the steps, that drive invention (materials development, physics discoveries, and disconnected science that bring about invention) in some cases luck. but I loved the piece and learned something new today which is always great
Edison's biggest contribution to invention might be industrial-scale R&D. He could brute-force invention by finding good engineers who had the potential but not the resources to invent and hiring them into well-equipped workshops, backed up with lots of technicians to do the time-consuming work of construction. A great improvement on the old approach to technological advancement: Waiting for someone wealthy enough to do it as a hobby. He did cultivate the image of himself as the super-inventor though. He knew the importance of branding, and put his name on every product his workshops produced.
History has indeed been cruel to the true inventors and innovators. Worse than that is that falsehoods have been perpetuated in schools and have served as inspiration to contemporary scallywags such as the recalcitrant individual to which I believe you might be referring.
No not trolling, being honest, Steve had some stinkers that fan boys love to forget, and technology grows slowly with big jumps occasionally, if I was to congratulate him on anything sales, salesmanship and marketing, tieing the price of iPhone in with the phone contract was genius, but inventor? (which the discussion was about?) Bell invented the telephone? Or Marconi the radio? It's why I love this channel and others.
I MADE A MISTAKE: I stated that if you add more light bulbs in parallel the bulbs will be dimmer because the resistance will go up. The light bulbs *will* be dimmer if more are added in parallel but not because the total resistance increases. In fact, the total resistance will decrease as they are in parallel. The bulbs are dimmer because more current is being drained from the generator and the internal resistance means that the *voltage* over the individual bulbs will decrease.
I am so sorry, I should have realized what was happening with a bit of thought. Also, now that it is up, I cannot edit my video (although I did add a little card in the corner).
Also, many of you were confused by my quick transition between Edison's 3-wire DC and Westinghouse's and European AC systems. I should have been more clear about when that transition happened, sorry.
No problem this is second nature to myself I wish you would have clarified earlier about Edison starting out with direct current
Ha, ha!!! I was about to point out that you had the relative resistances backwards but you realized it first.
Caught that right away, was about to stop watching thinking this chick is way over head, but you proved me wrong. Bottom line, it's all about the wire thickness. For a given amount of power used, the higher the voltage, the thinner the conductor. Also the rest of the world uses more aluminum wiring, less expensive than copper, but lesser ampacity. All this talk about AC electrical transmission, and no mention of Tesla?
@@ronalddaub7965 Edison and his DC is fairly common knowledge. Where have you been, Ronny?
Is that what we now call a 'brown-out'
Also, why does the UK have a fuse in their plugs when the US does not?
32 years in power transmission and still so much to learn.
People like you make UA-cam awesome.
Thank You.
Thanks 😊
I love your enthusiasm, but showing photos & graphs then throwing your bare white contrasting hands around makes the transition from one to the other less than palatable. Thanks 🙏🙂Maybe wearing darker apparel would be all that’s needed. This is wonderful show!
Please Dont Curb Your Enthusiasm! ❤
@@barrywhite9114Kathy has explained that she was diagnosed with ADHD and that moving her hands is, for her!, a necessity to be able to think.
I recommend to watch that video.
_"People like you make UA-cam awesome."_
There are so many people, like her, that make UA-cam awesome that I prefer UA-cam videos to TV shows. I'm not only entertained, I'm also informed.👍
-Thanks for your hard work and research on this. The reason the Chicago Exposition was such a triumph for Westinghouse has to do with Edison refusing to sell lightbulbs to a competitor. That wonderful genius Nikola Tesla took a look at the problem, and invented fluorescent bulbs, which cut Edison out of the picture completely. That pretty much was the reason the "War of the Currents" came to an end, as AC could be distributed over thousands of miles, whereas DC was very much local-distance only. Edison gets far too much credit, and Tesla far too little.
I have to agree with you, that Nicola Tesla formed the basics of the AC Power Grid, but Edison took all of the accolade. Tesla died virtually penniless.
And now it is starting to swing back the other way with HVDC being used.
Tesla didn't invent light bulbs. She has videos on their invention. She has one on the War of the Currents too.
She has several Tesla videos too. Check them out!
Edmund Germer was a German inventor, recognized as the father of the fluorescent lamp.
The other weird thing about Japan (well, the other weird thing about their power grid) is that half of it is 50Hz and half is 60Hz, because two different cities started electrification projects around the same time, one using American-built generators and the other using European equipment.
So which city use 50Hz and which city use 60Hz? Thanks.
I can't even imagine how this can work. There is effectively two different grids, then, right?
@@oscarn-The grids were linked using rotary frequency converters originally. Nowadays they use HVDC links to share power.
@@rickykngoall of Kanto, Tohoku and Hokkaido use 50hz. And all of Kansai, Chugoku, Shikoku, and Kyushu-Okinawa use 60hz.
The Chubu region is split, where all of Yamanashi is 50hz, and all of Aichi, Gifu, Fukui, Ishikawa, and Toyama are 60hz. The prefectures of Shizuoka, Nagano and Niigata are where you can find both 50 and 60hz depending on the municipality. Where Shizuoka and Nagano are mostly 60hz, and Niigata is mostly 50hz.
This is truly weird and probably would've spurred that HVDC transmission projects.
Necessity is Mother of Invention and the rest is history!
I am a data com engineer. I am not an electrical engineer. I remember the fun (lol) of trying to calculate the energy requirements for data center PDU's which had 3 phase incoming, feeding both 48v dc networking gear + 1000+ servers @ 110v ac + sufficient battery capacity in AMP/hours + generator requirements beyond that, etc, etc, etc. I had to attend 2 weeks of classes with APC to learn some of what you explained in a few minutes.
You do an excellent job of explaining things in an understandable manner. Kudos!
Over 1,000 servers? You could just replace it with 1 mainframe the size of a refrigerator, which can virtualise over 4,000 "servers"
1 machine v. 4,0000 the choice is clear
@@rty1955so you want him to use current tech 20 years before it was created. Also you hav3 no idea what a mainframe is, lol.
@@donut3946I worked on 'Mainframes' in the 70's. No such thing as a Server then.
Virtual systems run on Servers not mainframes.
@@rty1955 No problem he'll just time travel and get that done based on your suggestion.
@@rty1955rest of comment not showing
We use BOTH voltages in our US homes. All my heavy equipment uses 220 such as cooker hob, oven, A/C condenser unit, pool pump motors and clothes dryer. All regular light duty stuff is 120 which is more than enough for lighting, kitchen small appliances, tv, computers etc. I think our electrical system makes complete sense. Yes, we have electric kettles and toasters running happily on 120 too.
I recall from 1975 when we first came to the US that my wife wanted to use her UK sewing machine so I wired up a connection to the cooktop 240 volt for her and she was able to get sewing.
Yeah but most other countries at least in eu use 230v and if you have heavy use you can get a 3phse where you can get triple the power
You are correct. Most homes have at least 220v coming to them in the US. The neutral conductor allows us to ‘split’ that voltage into 2 110v legs. While 110v is less efficient, it’s physically safer to the user. There’s is a heck of a difference if you get shocked with 110 vs 220.
@@yolowolfyt 3 phase and a myriad of voltages is available in the US too in heavy use area.
@@yolowolfyt no home needs three phase. Larger users such as public institutions, offices and factories all use three phase. Even my church uses three phase. Three phase power lines run through every neighborhood. If your small farm needs three phase for certain new equipment you can have it wired in. It’s just a matter of having an appropriate voltage for the need. I am happy to have a safer voltage of 120 for all normal outlets. With the advent of led lighting, flat screen TVs and small appliances the wattage needed goes way down anyway.
If you're in the US, you haven't used 220V power since the 60s. The US residential grid today is nominally 240V.
At 2:35, the correlation between loading and resistance is backwards. The more loads you have in parallel, the LESS resistance you have, not more. The reason why the "popular" lines weren't as bright is due to a higher voltage drop across the conductor. More current means higher I^2R losses.
I think she just meant that there were more resistive loss in the wires when said wires supplied more loads.
Yes, I was unclear what she meant. If more loads are turned on then, from the point of view of the generator output terminals looking towards the loads, the system load resistance is reducing not increasing. As you say the losses in the distribution conductors will increase because the reduced load resistance causes more current to be drawn assuming a fixed generator output voltage . Hence I^2 R losses have increased and load resistance decreased.
I did enjoy the video and learned why USA uses 110 and 220,🙂
@Patrick Ray You're absolutely correct. I was about to make the same comment and started by checking whether anyone else made it already. Another reason the "popular" lines were not as bright was voltage loss within the power source (in addition to the voltage loss you mentioned in the wires).
I agree Kathy has confused the correlation between resistance and load/demand current flow in a parallel circuit as illustrated. The more light bulbs on at the same time are going to reduce resistance in the circuit and allow more current to pass/require more current without exceeding the ability of the generator or a voltage drop would occur, dimming lights. Voltage drop being a symptom of insufficient generation or resistance between the generator and load.
I don't know a lot about the Edison system [why I am watching this] but it seems it was a DC system rather than an AC system and I wonder if it also a series circuit system rather than a parallel? That would explain increasing resistance as more lights/load was added.
09:00 Oriel Chambers, Liverpool, built in 1864 is regarded as the first steel framed building in the world, and the design principles were brought back to Chicago by architect John Wellborn Root who was studying in Liverpool as a teenager, during the time of its construction.
There was the Shrewsbury Flaxmill building built by Charles Bage back in 1797. Cast iron, rather than steel but served the same purpose of being A) fireproof and B) offering maximal interior floor area for the industrial machines. It still stands, worth a visit.
The shrewsbury flax mill in Shropshire UK built in 1797 was the first metal framed building in the world.
Scotland and England were very creative in the uses of cast iron and steel.
I enjoy your discussions on the history of electricity. My dad, like me was also an electrical engineer, said that in the early days of development of the light bulb, it was difficult to make the filiment thin enough for a higher resistance to run on 100 volts. The tungsten filiments were coiled to keep them compact so they didn’t have to have wire supports in the lightbulb. The 220v made the light bulb more difficult to make. Years later by better manufacturing techniques, they were able to make thin high resistance filiments. The 7watt candelabra light has a really fine filiment that was fragile and it took even longer to develop. When I grew up in the 1950s, when decorating Christmas trees with these bulbs the filiments would break easily when dropped.
Remember that the only use for electricity in the early days was for light bulbs, so making practical filiments was important.with time light bulbs got smaller, but they were then made for lower voltages and ran In series.
PS I worked in two Silicon Valley laboratories where they developed the first practical LEDs in the late 1960s, that is Fairchild semiconductor and HP laboratories. HP first used them in the HP-35 calculator. “You could get them in any color as long as they were Red”! To paraphrase Henry Ford. Ross
She has videos on the development of light bulbs.
😂you could get them in any color as long as they were red.
I had a HP-33 in 1978 with red LED’s.
@@ursus9104 I also had an HP-33 many yrs ago.
Maybe you should visit Cragside one day (the first house in the world to be lit by electric light) to disabuse you of the notion that it was only for lighting.
As a former electrician, I've known the how of these things but I've never known the why they came to be so I absolutely loved this.
Me the same. Good work from her.
Me too.
If you are an educatated electricition,you should know that 220 volts is better!
Have you any experience at all?
Please do some research on electrical distribution as it is why we have what we have. Also, check upon what 2 phase ac consists of. Just because one system identifies 2 phase conductors does not make the service 2 phase. 240/120vac single phase as provided as residential services occurs in almost all homes in the US. 2 phase distribution consists of 5 wires. Alternators are used for ac distribution. Generators are strictly dc.
Nice explanation!
Skyscrapers also needed power for elevator motors, without which there would have been no market for buildings over 3 or 4 stories. The side story of Otis Elevator and particularly of Otis's initial emergency brake system (which was little more than a carriage leaf-spring) is fascinating, and he too presented his invention at the Worlds Fair. I read once that with dozens watching, he would stand in his demo elevator and with a chop of his axe, he would cut the rope holding up his elevator car. Instead of crashing to the ground, which was VERY common in those days, Otis's demo car would only fall a couple feet before that leaf spring would open up, lock into the shaft structure itself and stop the car, he sold beaucoup elevators and cemented his legacy in history.
And separately from that, plumbing eventually DID make it to downtown buildings, not only to provide water for the humans to drink or to flush with in the buildings, but also to provide water for firefighting purposes; probably something that Chicagoans were super in favor of after The Great Fire. Even today, we still use gravity and the "column of water" method to provide steady pressure and flow to every faucet, tap, or toilet in a building or area, and the best way to do that is to use electrical pumps to push the water up into a water tower for supplying a wide area, or up a building for storage in one or more tanks on the roof for supplying that building. It would certainly be preferable to have running water (even if it's not heated!) than it would be to carry a nearly 43-pound 5 gallon bucket up the stairs to your office desk or factory station every morning for your day's expected water needs!
Electricity was for so much more than mere lighting. So as Paul Harvey used to say, "...and THAT is the rest of the story".
Thank you!
You don’t need electric power for lifts. Hydraulic power works perfectly well (and was standard in most European cities until the 1940’s).
Hydraulic power lines were more vulnerable to bomb damage however.
The old high pressure water mains were repurposed in the 1980’s for telecommunications conduit.
Early elevators used steam engines for the propulsion power.@@allangibson8494
Thanks for the extra reading! It must have been fascinating to watch the live elevator emergency demos.
@@allangibson8494 Only if you have short elevators, taller buildings would require that the piston be potentially hundreds of feet below the bottom of the elevator. The freight elevator of one of the local buildings has a shaft of roughly 900 feet, meaning that the piston would need to be at least that long and buried to that extent. And the other elevators would need to have shafts of closer to 400 feet going through many floors.
AFAICT, around here somewhere around 4-5 floors is where it starts to become a bit more of a toss up as to which technology to use.
USA uses 240V, check all the house fuse box, it's 240V at the entry point. We just split it 120V and 240V as needed for what ever appliance is rated for.
Australia has 240v between Active and Neutral / Earth. If we go between phases like you are describing, we have 420ish.
@braxtez3745
I am in Australia now. Didn't realize 240v was standard here. Even car 12v inverter is 240v. I forgot my 12v inverter home and had to buy one in Australia. Luckily the laptop charger takes both 120v and 240v so no worries but the plug is different as US uses two vertical plug while Australia has two angles. Found an adapter and it's working out well.
Using the 220 volt for all appliances is 20% more efficient.
What is not commonly known is that Germany used to have a 115V+115V AC system when the Schuko plug was first developed although there was never a 115V + neutral version. It is why, to this day, in those countries where the Schuko plug is standard, like Germany and the Netherlands, domestic outlets are not polarised. Whilst there is a neutral + live(hot/line), it's completely random which pin is which when plugged in (which isn't a great mix with Edison screw light fittings as there's a 50:50 chance which way a table lamp will be plugged in (and it also means that there's a 50:50 chance than any single pole switch will be on the neutral).
These days it's different in Germany and the Netherlands where they tend to supply domestic properties with three phase and tap off individual single phases at 230V for circuits (although more powerful appliances, like ovens, will often have more than one phase connected).
Such is the way with legacy systems (of course North America didn't used to have polarised receptacles either; that was introduced later by widening the neutral blade).
This reminds me when living in West Germany in 1955, ("Army Brat"- Dad was assigned there.) the German house we occupied had 110 (115?) volts electrical service. That meant we could use our U.S. made appliances without requiring the use of step-down transformers. This just required Schuko to Edison socket adapters.
Then, one day, teams of electricians (lineman) rewired the village of Bad-Windsheim for the then-standard of 220 volts. Dad was prepared with two step-down transformers and 220V light bulbs... We arrived home later in the evening and my brother and I had fun, running ahead of my father and turning on the lamps in each room and thrilling at such bright lighting for a few seconds.
Very interesting! Same goes for The Netherlands, except here it wasn't 110+110V but 3x220V resulting in 127V to ground from either pole.
Steve Jones I’ve always wondered why it was the neutral blade of the plug that widened instead of the hot? Is there more potential for heat on the neutral? Is that why it was decided to make that blade larger rather than the load blade?
@@deanbortz7747 Personally I've no idea. the current should be identical on both (or GFCIs would not work). In every other system I know of with polarised connections, such as those in Australia/NZ and the UK, the neutral and hot/line pins are exactly the same size. It's the shape of the plug that then ensures polarisation. In the case of UK plugs, they all have three pins and only go in one way. With the Australian system, the pins are angled so a two pin plug (as well as a three pin one) will only go in one way.
As the addition of polarisation to the North American system was a retro-fit, then they had to maintain compatibility with earlier plugs and that was done by just making the neutral blade wider. I guess it could have been either.
As a side note, the Australian plug design is the work of the same man as the classic North American plug, one Harvey Hubbell. What was later adopted as the Australian plug was designed and patented by him in 1916. He had intended that it replace his earlier plug (which he'd designed in 1912) as an improvement, but it never caught on. As is often the case, compatibility mattered more than functional improvements. Thus the Australians, who were later to electrification, standardised on that plug layout in 1917, reputedly because it was easier to manufacture in Australia than the British round pin plug which required solid brass pins rather than flat blades (the old British round pin standard is still in use in some countries, like South Africa and India).
@@TheEulerID In UK the Earth is connected to the "can" or "chassis". When I moved to Hanau from Norwich I was always careful how I plugged in my soldering iron. One day I forgot to take care and "soldered" 220v into my TV while repairing. The Eeprom "window" had black specks under it. ..... I will have to bike-ride that Lauffen-Frankfurt "3ph Trasse". I am 68. Cheers.
When in EE school I got some of the history shown here but it was new to me about the series DC generator/ 3 wire practice. I have worked in steel mills where it was not unusual to encounter motors from the 1910s and MCCs built in the 1920s. The control distribution of the DC to cranes was especially interesting. At 4.00 minutes the diagram reminded of a simple thing we did to monitor the Crane 240Vdc supply. We used 3 240V light bulbs, 1 wired leg to leg and the other 2 from rail to ground. Any fault resulted in a change in brightness to tell us to go find the fault. Working with technology from 1920s and up was a fun challenge. BTW some cranes still used control panels made in the 20s as late as 2010. The same crame had some mechanical parts that had patent numbers fron the 1890s. It was an adventure!
Your article on a new design of incandescent lightbulb (G2, 13 January) perpetuates the common myth that the original was invented by Thomas Edison. While a number of people were working on this at the time, it was the British scientist Joseph Swan who demonstrated the first viable incandescent electric bulb in 1878, some 18 months before Edison did. Edison, however, had the perspicacity to file his patents before Swan (and before he’d produced a working example).
Dr Ian West
Jackfield, Shropshire
And yet multiple court cases filed in US courts trying to break Edison's patent for the light bulb due to prior art all failed at the time for lack of evidence.
Edison has been regarded by many as a thief.
At 12:24 Kathy mentions higher-powered devices requiring higher voltages. I might add to her explanation: This same high power could be achieved with 120 VAC, but by stepping voltage up to 240 VAC the required current was cut in half (Power = Voltage x Current). Thus SMALLER CONDUCTORS could be used at 240 VAC vs 120 VAC.
What is vac?! 220-240 volts is allways better than 110 volts!
Smaller conducters!? What do you mean?!
@@GeirRssaak Conductors are sized according the the rating of the circuit breaker, which in turn is sized according to the load, and the amount of current required for the load. Other rules apply, but that is the basics.
Hello and thanks for this video. In Belgium, they went from 110 to 220 in the early 1950's. That's why old folks had huge auto-transformers at home if they wanted to use their old equipment.
Worth it, 230V is so much better
@@m0r73n It happened in my city in the late 1970s, and the transition was quite smooth. Autotransformers were a no-no (and still are), we used "real" transformers with insulated windings. I don't think that the difference between 127V and 220V mattered much then. Residential consumption was very low, we did not have today's high-current toys like 10KW electric ovens and 20KW water heaters. My parents' apartment had a 20A (2.5 KW at 127V) input breaker and it never tripped.
At my family houses, it last a decade before buying equipment that worked on 220V, I'm from 66 and I remember these small transformers in use.
@@jmi5969 Also 120V has a lower potential energy than 240V resulting in a lower risk of fatality and allowing for smaller and more space-efficient plugs.
@@davidperry4013 One other issue is arcing behaviour: the "american" 100-120V series arc is less persistent and ultimately less dangerous than the "european" arc. A collateral, probably unexpected, is that the European arc fault detetection devices are somewhat simpler and less prone to false positives than the American AFDDs.
As for the size of power plugs - is there any need to make them smaller? our hands remain the same, and old folks likes yours truly aren't that good in handling small things.
Great video! Interesting info about filaments. One correction is that we do use 220V in the USA, it's just split at the home into 2 110V legs, just like the light bulb diagrams you presented. 220V is brought into every USA home from the pole.
220 v is phase to phase voltage, and 110 v is phase to neutral. From the pole the single household picks phase to neutral, while relatively large customers pick 3 phase and neutral, thus they have options: utilise 220 or 110 volts. 3 phase motors consume 220 volts - 3 phases without neutral, home appliances- phase and neutral 110 v. The 3 phase is essential when rotating magnetic field should be established in electric motors without commutator brushes.
@@khatokhato9350 It's 380 V in Europe for 3 phases. Again, outdated infrastructure.
@@lepton555 Noting that the 230V AC nominal is phase to phase from the 3 phase and not phase to neutral. In the UK and Ireland (which are all decidedly in Europe despite Brexit) at least the three phase is 415V. I am not sure you can even get 220V from 380V three phase.
That is exactly what we do in Trinidad and Tobago we use 110 v however 220 v can be connected from the panel with the 2 110v I currently have 1 220v plug for my washing machine and my welding plan
@@winstonseecharan6321 that right, but Kathy she said u s a used only 120v, look 120x 2= 240v 6321 u understand this I a greed with U 👍👍✋.
In the past 130V incandescent lamps were available for rural areas where the voltage was not that well regulated. An incandescent lamp burns out exponentially faster as the voltage increases and the higher voltage lamps would have a much longer life.
Another trick before LEDs became popular was to use 28V lamps as indicators in 24V circuits. The indicator would not be as bright, but the lamp would last substantially longer.
They actually had invented light bulbs that would never blow do the manufacturers got together to make it compulsory for to have a set life time in hours for incandescent light bulbs ,the word for it now is opalescence
@@noelburke6224 While there is actually a word opalescence (meaning roughly glittering multi-colored) you probably meant planned obsolescence.
There was never a light bulb which never blowed. However, in building a light bulb you have to find a compromise between efficiency (hotter is better) and live time (cooler is better). In order not to burden the customers with decision, the light bulb producers DID have a secret agreement on the bulb life time. Purely coincidentally, that did not harm profits.
130 volt bulbs are sold now as “long life” bulbs. Ordinary incandescent bulbs are now outlawed in the USA but specialty bulbs are still legal.
When I was a kid, LEDs were still new. A lot of kits and tutorials still featured 4.5V bulbs for 3V circuits. They worked as indicators.
@Andy Peek It's funny but torch bulbs are the other way around - running a 1V bulb off a 1.5V cell. (Commonly a 2.5V bulb off 2 1.5V cells.)
Thank you for your great job. There is one mistake around 2:30. More lamps will make less resistance instead of more. And more current will drop the supply voltage and therefore dim the light.
I am so sorry that I had such a brain fart on that one, of course that’s why more lightbulbs in parallel will be dimmer. Thanks for correcting me so politely.
@@Kathy_Loves_Physics I just want to let you know that your audience did pay attention. We learn a lot from you. Thank you.
Yes - I caught that error as well. "Zoe the Robot"
Hi from 240v UK... We had a novel experience a few months ago. A fault in the electricity 11kv distribution, left us with just 70 volts. However all our LED lights were just as bright at that voltage. Our 2Kw cooker elements would not heat up at that voltage.
many led lamps incorporate a constant current supply or regulator, dropping the line voltage (within design limits) will still result in same current delivered to the LEDs
Also from the UK but didn't know about this, what part of the country did it happen in exactly?
Hi @@Admiral_Jezza It happened on the outskirts of the Wrexham Industrial Estate. I am still trying to work out why we went to 70v, and not zero. Maybe the 11Kv line only had a short on one of the phases. The arcing lit up the sky for several minutes, even though we were 5 miles away.
Great job. At 12:35 into the explanation about home electric dryer powering, there are not two phases here. There is only one pole transformer and only one phase of the 10 KV high-voltage tap. It is true that, in reference to the center tap, the two 120 volt ends are 180 degrees out of phase, yet still the dryer works on a single phase. It is not a 3-phase dryer.
This is correct
Still single phase at 240v
Yep. That is why a point is made to call that split phase. As in being a split phase of a single phase. Or a single phase being split by transformer tap.
Very interesting with lots of history. I spent 50 years in electrical / electronic engineering and I've learnt new things watching this video! Thanks a lot, Colin UK
Like DC has a neutral and can be stepped down? I learned that today too
Great analysis. Lesser minds would have looked for whoever, in the entire history of electricity, happened to generate 120VAC first and just stop there. Kathy rightly realizes that it's FAR more important to follow the influence and adoption of an invention than just its first occurrence. Great stuff.
Interesting set of historical facts!
When comparing 3ph and 1ph and 1ph/2legs (now called "split-phase") there are quite a few differences in how those are connected and work. For example in the Delta configuration there is no ground wire. You can get 120VAC on one node, 208VAC on two nodes, and 480VAC on all three. In the Wye configuration you do have a ground wire (so four wires instead of three) and that allows more redundancy if a phase failure occurs.
Your typical 220-240VAC residential circuit used to be called "2 legs" not "2 phases" because the two hot lines were two circuits providing the same phase BUT opposite voltages. Now it's called "split phase" because --as you correctly point out-- if you call it like you see it, each of the hot lines is 180° out of phase with the other. The disadvantages to this is that there exist periods of 0VAC (every 1/60th of a second on 60Hz systems) whereas if offset by a real phase difference there would never be a 0VAC spot, but there would also never be a 2x1ph VAC spot either. Motors (HVAC equipment, pumps, etc.) like this more. However, water heaters and incandescent light bulbs don't like the 0s mixed in with the 240s. (And yes, there are plenty of 208, 277, and 480VAC incandescent lights... mostly industrial and businesses in the US.)
Transformers are not cheap, so one of the compromises is what voltage to run to a residential neighborhood to save money on transformers. A 4KV-->240V transformer is much cheaper than a 14KV or 40KV downconverter.
Things like compressors like 0VAC points (they are motors, after all) but things like welders don't. All of these are compromises. The reason for the compromise is the desire to run higher voltages to reduce amperage thereby allowing higher gauge wire (thinner) with a lower ampacity but saving money on copper or steel (must use even more steel for same ampacity).
And finally, there are power-factor correction devices (think "huge capacitor banks") that store the energy during non-0VAC points and release it at 0VAC points to make for a constant voltage. This turns horrible-PF devices like HVACs from 0.2-0.3 to near 1.0. Electric Utility companies in the US like businesses to have a PF close to 1.0 an reward businesses with much better pricing (because they size for average use, not peak) and that often covers the cost [over time] of the PF correction device. These are more often seen in the 480VAC and higher world.
Best wishes
I was just reading about power factor a few days ago, prompted when looking at the schematic for my Miller welder. It showed an PCF option so I delved into it. It was I think 4 x 200MFD run capacitors. There was a chart showing the amperage difference with and without. If I as welding all day I would be very interested as it indicated a fair reduction in power used.
that was one of the most informative and well written explanations of electrical power distribution in america as it is done today that I have ever seen. I'm a retired electronics tech and learned a couple of things and relearned a couple more that I had forgotten, thanks for the refresher course. :)
Power (kw) used by your welder is the same; just amperage in the lines feeding the welder is lower with pf correction. PF correction caps put voltage and current closer in phase. When 100% in phase, pf = 1. PF correction in residential systems is usually not an issue because you are not billed or penalized for power factors less than 1. With better pf, you may be able to get by with smaller gauge wiring, ie, if your welder is a long way from your service panel, but your electric bill is not likely to change. However, industry uses considerable energy, and pf less than 1 causes higher line losses for the power company. Power company will bill industry at higher rates for poor pf to cover these losses.@@stephensarkany3577
Edison was very concerned about safety and 110V is a little bit safer than 220 so far as electrical shock is concerned.
220V allows using smaller wire and thus its cheaper to implement.
I noticed this right away when I bought an extension cord in the Philippines. It's much more flexible than one from the US.
But Edison pushed for DC which is far more dangerous, it was Teslas 3 phase ac system that won the electricity war in the US.
Edison played the safety card because he wanted to use DC power. Not AC. Edison shocked his employees (as motivation and to wake them up), had a wire run around the shop that was used as pest control (not exactly something safe), he also electrocuted dogs to death to demonstrate the deadly unsafe power of AC current & an Elephant that was said to be bad/out of control after it attacked & I believe killed someone that abused the pour already often abused elephant.
Edison got to showcase his motion picture recording device. Along with this. The thing he tried to use his patents to basically be the film industry. But, a judge ruled against him and Hollywood was born. (Or something like that.)
I wouldn't say he was big on safety. As much as I'd say he was trying to turn the public on the much better competition. He was a businessman. If anyone today tried a fraction of the things he did the public would shun him so fast. People would be sending smoke signals before using the Edison Phone, camera, light bulb, or any other thing with his name on it.
Just a tip but you need a body mic (or a better recording location) to reduce the harsh echo of the room and better lighting (you're being lit from below). You tube has videos to fix these issues. Cheap things like moving blankets hung while recording will soften the sound and lighting. Great video and topic. ❤
I ask this question when I start covering electrical power systems for aircraft. The genesis is the light bulb. Aircraft use 400Hz to reduce the number of copper turns of the generators and reduce the size of cores in transformers.. On large transport aircraft with long cable runs, Aluminum is used and spiced with Copper for the generator feeders and the feeds into the distribution centers. On most commercial aircraft DC voltage is a higher 28 vs 12 on cars, similar purpose to save weight by making the wire size smaller because of reduced current. So happy to find your videos.
Correction - Aircraft use 400Hz to reduce the heavy Iron mass in transformers,
alternators and the like !
@@pjeaton58 Correct! I was going to say "inductors" but transformers will work.
@@pjeaton58 Thanks for the feedback, but I keep finding generators and alternators smaller at 400Hz
@@joeozzie1 yes because for a given voltage, the magnetic flux proportional to volt-seconds, is reduced at higher frequenies requiring less core. Also since reactance is proportional to frequency, the number of turns can be reduced while keeping magnitizing current the same. The reduced number of turns also reduces resistance.
Taken to the limit you end up with switch mode power supplies that use very small transformers operating at hundreds of kilocycles or even into the low MHz.
@@power-max Thanks, I thought so.
Such a great educator you are Kathy! As an electronics
guy, you have taught me what tech school didn't. Such as the "why" of electrical inventions.
The US actually uses 240V extensively within the home. The 120V service is center-tapped off a 240V phase on the street. Each side is 120V but on your electric panel, you can draw 240V. Electric baseboard heaters are generally wired to 240V in this manner and you could easily wire a 240V plug if you wished.
Using 120V for most outlets is far safer than 240V. Countless lives have been saved in North America because of the power outlet voltage, yet the center-tapped power supply offers 240V when you need it - such as with baseboard heaters. It’s actually genius.
Can confirm 240v. I live on long island NY
Canada is the same way.
Because compared to the UK’s excellent designed plugs.. North American ones are an atrocious design safety wise.. sorry but its true
@@MrDodgedollaris that why only 6% of fires in the US are electrical and the UK is 12%? Fusing in the plug is not nearly as safe as central fusing or breakers, and much less safe than the gfci system used in the US for high risk circuits. Maybe it’s the little plastic covers that block the outlet holes you think are so safe? The US and most of the works solved that by having prongs that are much smaller than a toddlers fingers!
US is 13% uk 15%
Love the enthusiasm and details covered. The cohesiveness held me all the way through and I can't wait to see the next one. Well done.
Fantastic presentation of some important power history. I'm a retired EE/CS and while very well read on early AC power as well as some on Edison's DC, the use of +/-110 V by Edison as a means of copper savings was not known to me. Impressive research, and a most enjoyable presentation.
I'm looking forward to your book and thank you for your outstanding work. One piece of history I'd love to see you do is Edison's early attempt to use earth as neutral, and the resulting shocking from step voltage potential. Another would be the insane WYE multiple earth grounding practice which was used to protect motors, but violates transformer isolation and thus injects massive neutral current through the earth as well as creating a problem similar to but lower than Edison's earth as neutral.. Zipse's work is a good starting point.
Thanks again for all your outstanding presentations. I'm a big fan.
Bruce
Glad you liked it Bruce and am interested in what you think about my next video on 3 phase
Edison was the crooked businessman; Tesla was the true inventor.
@@foureyedchick life is a bit more complicated, both Tesla and Edison did things that today we would consider dishonest and Edison did invent stuff quite a bit
@@foureyedchick whoa, you should change your name to Racistgirl. Your entire comment is both ignorant and uncalled for.
@@brianm1916 And what are YOU? A meddler in somebody else's conversation? What are you? His lawyer? His gay lover? What should your name be changed to? "Brian M --> Brian Misogynist"
Wow, I didn't expect this to go that technical into electricity. Well done.
I would love to take a whole semester course of STEM History from you, Professor Kathy. So fascinating and you have an excellent delivery.
@@xyz_zyx "Pesky?"
Wow... I thought this was 2022.
🤣🤣
The more popular line would have "Less Resistance as load" and "More Current flow" as a result of more lamps attached. See Ohm's law: V=I*R where V is Voltage, I is current, R is resistance. More lamps in parallel would lower the overall resistance, and cause more current to flow. Now if you discuss the feeder cables, the more popular line (might) be longer, due to more customers spread out. In that case the feeder cable would have more resistance, and hence there would be more voltage drop in the line.
It depends how Edison noticed that there was more load on the more popular line. As the electrical resistance goes down the mechanical resistance to turn the generator goes up. If you are at the power plant measuring the power it takes to drive the generators you can say that the more popular line has more resistance.
@@tapioleva9851 But it doesn't. If we're talking about electrical resistance -- which we are -- it goes *_down_* when a greater load is applied. (i.e., the video is wrong and "hsailer" is right.) Yes, it takes more torque to turn a generator that is powering a heavier load, but that is not "resistance" in any proper sense.
@hsailer Thank you for saving me the time of commenting the same thing.
The only way more light bulbs add more resistance is if they are wired in series. Adding more resistors (bulbs) in parallel only lowers the overall resistance of the circuit - even regardless of the length of each line. For instance, one light bulb added 50 miles away might not lower the resistance of the circuit as much as it would if added 10 feet away (due to the inherent resistance of the 100 miles of wire), but assuming that 100 miles of wire was already there and the resistance between them at the ends was effectively infinite, dropping in a 120 ohm bulb would drop that infinite ohm value down to 120 ohms - therefore a reduction in resistance overall, but the wire may look like a 240 ohm resistor in series with the 120 ohm bulb. Either way, it would be like having a 360 ohm resistor instead of a 120 ohm resistor, and that is still smaller than infinite.
"the feeder cable would have more resistance". Voltage drop is what causes the lights to dim. No matter how long or short the line is the voltage drop increases as the current increases. While the length of the feeder will affect the voltage drop as it increases, the resistance of a feeder is low enough that current increases will affect it more than length.
Parabéns pela ótima aula. Sou engenheiro eletricista formado a 40 anos e está é a primeira vez que alguém consegue explicar porque 110 ou 220 volts de forma tão didática.
Great job as always. I remember my brother trying to explain some of this to me years ago and my eyes glazed over and I passed out. You actually made it interesting!
I am simultaneously pleased that you liked it and sorry for your brother :)
While it is nice you got it now as this is a pretty good video.. it is not a "feature" to get bored with knowledge.
wr
##ò
You start out talking about Edison's dynamo as DC, which is true. The system that we use today is AC. You even talked about the transformer with regard to Edison's system. It is physically impossible to have a DC transformer. That is one of the reasons that AC became preferred, it was impossible to transmit power over great distances as the voltage dropped quickly over the lines. Edison's plan was to put a generator on every block.
A good presentation concerning the history of modern electrification of the US and world I would like add the following.
December of 1887, Tesla filed for seven U.S. patents in the field of polyphase AC motors and power transmission.
These comprised a complete system of generators, transformers, transmission lines, motors and lighting the German
system is based on Tesla's alternating current system which went on to illuminated 1893 World's Columbian Exposition
in Chicago.
Ha! Kathy has a vid out on just that(3 phase electrickery). Its really good too.
glad you brought that up, no one remembers that edison held back the country from going electric because he fought tesla tooth and nail because he is a fucking egomaniac and could not accept the truth and the real genius behind modern elictrical power, i blame edison for tesla dying broke
@@jimmieroan9881 - I think Tesla broke himself with his fixation on Tesla coils and wireless energy transmission. He built the hugely expensive Colorado Springs lab shot lightning bolts around but never created any marketable products from it. The Wardencliffe Tower on Long Island was the final straw and even his most ardent investors had to say no, we are going to build a system to send electricity through the air for free. Great creative thinker and inventor but no practical engineering and economic sense.
It an't modern ,it's shambolic.
Almost all houses in the US have 220-240 volt and most higher draw equipment, electric water heaters, electric ranges, clothes driers, and are 220-240 volt in most US homes. It comes into the house as two 110-120 volt to get the 220-240 volt, but most outlets use only one or the other side so have 110-120 volt for most electric stuff. It is crszy so many people say the US is 110-120 volt when we use both.
Like here Finland one phase is 230V 50Hz and between phases 400V (3 phase)
At 230v the advantage is that thinner cable can be used relative to the load than the 120V system uses.
The first use of the iron skeleton frame building method was use for Ditherington Flax Mill in Shropshire, England in 1797.
This method quickly spread, resulting in it being used to construct Skyscrapers in New York.
Yep, this was the usual american version of history on so many levels.
We do use 220 (240v) That's our single-phase standard. We just split it into two legs balanced around ground (center tap on transformer tied to ground/neutral) for light load resi.
Wow, Kathy, this was extremely informative on so many different levels. You touched on it, kind of, but even with 220, we are still 110! It’s just that the other leg is inverted to the main leg so that they sum to 220.
The other leg is not inverted, it's the same as the first leg. There is no second phase.
@@xiaodingjones1554 I was looking for someone to correct her about phase separation angle and adding phases. Single phase with center tapped secondary ground/neutral. The legs Y-me referring to are these opposite sides of a single phase.
@@xiaodingjones1554 In the US we have split phase, so the phase of the two legs are 180 degrees apart (technically in relation to neutral, but that gets a little more complicated to explain)…
US standard voltage today is 120. In most utilities it’s 120 +/- 5%. Standard residential is 120/240 single phase with neutral. Three phase is either three wire with neutral 120/208 Y, 240 delta or 277/480 Y with neutral. ST substation engineer.
I repaired a fire pump in the basement of a hotel in Manhattan - the electric motor was DC - the current was supplied by Con Edison.
@@paulsawczyc5019 this video seemed to suggest that 2-phase is still a thing, which is actually a rare find in some of the older u.s. cities much like your Con Edison DC motor.
i had not heard of a balanced dc circuit before, always thought that was strictly an ac thing.
Literally power transmission is 240V single split phase in america. It’s only when you get to the lines that service a row of houses, after the transformer with a center tap on the low voltage side, do you get two 180 degree phases of 120V from a single phase high voltage supply. It’s why every house in America has 240V available at the breaker box.
Great work, Kathy. Having taken electrical wiring training many years ago, I learned something new about the origin of 110/220 volt circuits.
Your Kitchen Range uses 240V, Dryer 240V, Water Heater 240V Air conditioner 240V unless you use gas and prop windows open you do have 120 and 240 in the USA and have for many years. OHMs LAW can explain this all very well.
@@chrisowen2925 Ohms law does NOT explain it. In fact it is NOTHING to do with it.
It is to do with the voltage across the windings of coils on the secondary side of the transformer.
It's to do with the formula for the voltage output of the transformer which is:
Vout = Vin.(N2/N1)
Where N2 is the number of turns on the secondary side, and N1 is the number of turns on the primary side.
It is also to do with Faraday's law of electromagnetic induction and mutual inductance.
Nothing there about Ohms law whatsoever.
@@deang5622 And you trolled me again.
@@deang5622 - Ohms Law does have some effect, note that the AC Power is rated at 120 v & 240 v, however when you look at motor nameplates most at rated at 115v & 230 v. The reason is voltage drop which can be calculated using Ohms law for AC RMS voltage/current. The reason for the 5 v difference is that AC motor companies allow for a 5% drop in line voltage due to wiring resistance and transformer winding resistance.
Actually...just about every home in the US has 240V. They just break it down into 2 legs of 120V for lower current uses.
The whole point of higher voltage is less current for the same amount of power. POWER (W) = Volts (V) X Current (A).
Current is what heats up wires. For a given amount of power needed, you can safely use a smaller gauge of wire with a higher voltage.
Saves Copper...saves Money.
(Then there's 3 phase...but that's another story...:-))
I thought it is the other way around no ? 110 v requires thicker wires than 240 V.
She went through book history rather than the engineering and logics.
It's why letting the Liberal Arts portion of A University teach Applied Science is not a thought out idea.
I think our Traffic lights mainly run on 3 phase...
@abigmonkeyforme Thanks.
@@AncientWisdom222 Think of it this way: Countries with big copper mines "somehow" often found 120v more agreeable. Countries that had to import
copper found that 240v was quite good.
In Europe, there were many locations that still had 110V up until the sixties. There was made a large push here to change that to 220V. Up until now, there is still 3phase 230V in Belgium and Norway from which you can still use a floating neutral to make ~110V. That will actually cause a lot of problems for home chargers here, as the current will be a lot higher for the same power.
the US uses a similar system as norway. but a split 1 phase system rather than 3 phase. so in actuality every house in the USA is supplied with 240V, it's just center tapped so that 120v would not need to be phased out. EV, washing machine and hvac are examples of things that utilize 240v in the us.
@@dyarous where did you get your education?!
Ha-ha! You should get some education!
I grew up in a house in Auckland NZ that had 240 volts DC reticulation. In 1953 this was changed to 240 VAC. The house was very old and the cabling was rubber insulated running through exposed steel conduit down to the various very clunky switches made for DC.
The problem was that for 240 DC you only need to insulate for 240 volts with a margin. For 240 VAC you have to insulate for peak voltage which is 240 X 1.414 = 340 volts. Subsequently the rubber insulation failed livening the exposed conduits and we started getting nasty shocks. The landlord would not fix the problem so we ended up leaving the house.
Wow that's really interesting, thanks Colin. I didn't realise DC was used up to 1953! What part of Auckland? Where was the power station? Devonport? I imagine it had to be fairly close by to minimise line loss. Cheers.
@@peterhall9603 King's Wharf had a DC substation up 'til the '80's - some lower Queen Street buildings had DC powered elevators until then. The DC from King's Wharf also powered the trolley buses. Those trolley buses were withdrawn when the King's Wharf substation was closed.
@@laurencetucker9967 Thanks Laurence. I knew that the trolleys were DC powered but assumed it was a large AC to DC (probably rotary) converter somewhere. I remember the DC elevators too but hadn't thought about how they were powered. Cheers.
Very interesting lecture!
In Dutch we have a name for this phenomenon: De wet van de remmende voorsprong, the Law of inhibiting head starts. Those who implement something first do not get to incorporate later improvements that are incompatible with the earlier version.
Jump in first and commit to a new technology - you get the “less developed” form of that new technology
English needs a punchy phrase like that for this phenomenon. It is not quite the same as "technological lockin", which locks the whole world into (sometimes inferior) technology choices. Both are common.
120v going from to 230v is not a step up in technology. If you wire a broadcast tower for lighting in the pre-strobe days the FAA required that beacons on the tower consist of two 620 watt incandescent lamps. If your tower was tall enough you may need four or five beacons. In my now remote youth I asked my supervisor why are these lamps 120v lamps used on the tower instead of 240v lamps. He said "240v lamps only have half the expected service life." Europeans spent their money on tungsten rather than copper. Besides you don't want to do this any more than is necessary:ua-cam.com/video/f1BgzIZRfT8/v-deo.html
Not that I ever did.
Thanks for posting Kathy. Great explanation.
My house built in 1910 originally only had 4 circuits at 110v. I always wondered if it was missing a “leg” for not having 220. Thank you for the video explaining that it was normal to only have one hot and neutral at the time for residential buildings!
I lived in a house (Pittsburgh,PA,USA) that only had 4 110v (fused) circuits in the 1990s! My dryer, furnace and water heater were all gas, luckily. But doing something "crazy" like using the Microwave and say, the toaster or coffee maker at the same time weren't gonna work!
120V 60 Hz 30 Amp and a four fuse electric box, two wires leading to the mains, not today's 3
It's not normal to have multi-phase in British homes, but we have plugs with freaking massive pins for carrying 13 Amps, and that at 240 Volts. (3kW from any socket!) They were supposedly invented for our tea kettles. Full-size cookers have to be wired in, but we can just plug in anything else; I've never heard of a gas dryer before. ;) Even some heating can be done with plug-in devices, but sadly, standards have slipped to the point where the fire department recommends you never use more than 2/3 of the available power from a socket.
@@eekee6034 Lots of people in Pittsburgh have gas appliances as this area is sort of a "Saudi Arabia" of Natural gas. It's cheaper to use gas than electricity for anything that "heats" for this reason. Of course gas dryers do use electricity for the motor. It's the heat that comes from using gas.
@@jamesslick4790 Interesting! :)
Amazing description of all of how this all works! I knew about Tesla(Westinghouse) and Edison. Describing the reason for the country's uses of the different types of power that are used was amazing. I didn't know that it was more expensive for America to use 110, LOL! And now I know the reason why we stayed that way too! Thank you for such a great answer to such an interesting question!
Awesome video! very informative about the history of electricity transformation/generation!
One tiny gripe is that in the US most residential supplies are 240V 1 phase, not 2 phases 180 degrees out of phase with each other. The difference that can be confusing is that distribution side of the transformer utilizes 2 wires (1 line and 1 neutral wire going into the transformer) and the residencies side of transformer has 3 wires. The third wire is called a center tap and it literally taps into the center of the transformer coil supplying power to the residence. That's where the half voltage value comes from (half of the transformer coil turns being utilized for some loads). This is called a split phase supply and is 240v/120v from one single phase.
The neutral conductor for the residence is that center tap and that sometimes causes confusion since there is no voltage grater than 120v to neutral (some utilities supply split phase with higher or lower line to line voltage but it's the same concept). Just remember that the utilities' neutral wire and the residencies' neutral wire are absolutely not at the same potential in this scenario.
Right. the transformer out there is really a center tap on the secondary side. the primary is generally thousands of volts whose potential varies depending upon distribution. Primary/secondary are completely isolated thus the secondary could be all kindsa configurations.
I love these videos! Kathy is the only presenter that gives both technical and historical information. As shown in her videos, politics and human interactions produce not only significant results, or they ruin things for years. Gee, I thought scientists were only interested in the truth.
Thanks Kathy. I hope you also teach about Nicola Tesla, who provided importantly to Edison's DC generator advances, but was badly treated and not paid for his efforts as Edison had promised. Tesla was a brilliant, generous man whose story is unfortunately told. In fact, he is the reason for AC! Westinghouse recognized and helped Tesla develop much of the work resulting in the AC systems which enabled so many to benefit, because it's so superior to use over long distances. In fact, Tesla's work enabled Westinghouse to win a competition with Edison to light the exposition.
She has many videos about Tesla and Westinghouse, which I think you will find to your surprise may change your idealistic views of Tesla
You’ve crafted a decent story, and you even got some points correct like needing higher voltages to span longer distances. Please read NFPA 70E. 110-120 VAC is the desired voltages for plugs that the majority of people shall plug the majority of devices into frequently. The average resistance of the human body is about 110-120 ohms, so getting shocked by 110-120 VAC around 1 A is minimizes both injury and death. The reason I mentioned the NFPA reference is that it gives people more information to safely work with electricity.
Where the heck did you get an average resistance of 110 ohms from
A great video. I love physics and I love history. I see by some of the comments one person already made a comment concerning your error of more lighting filaments being more resistance which is exactly backwards but what astounds me is that you were able to mention the whole thing concerning AC without mentioning Nikola Tesla. And the reason the generators were in the basement before Nikola Tesla's invention was Thomas Edison was a DC man. DC cannot be transmitted over long distances so each building had to have a generator in the basement.
DC can easily be transmitted over long distances and it is very good for that, because the DC current lacks skin effect in the conductors. That's one reason why many of the high power links are realized with HVDC. In the early days the problem with DC was voltage conversion as it can't be done with traditional iron core transformers like it is done with AC. Anyway higher voltage is required for minimizing the transmission losses. Therefore AC was chosen instead of DC in most places.
@@laakeri84 Yep. And for a given size of conductor, the losses increase as the frequency increases.
Higher voltage means lower current - which reduces the I squared R loss. For example, a 120 Volt line carrying 100 amps will have 4 times the resistive losses as a 240 volt line carrying 50 amps.
Thank you.
You do not appear to mention that the standard today in north America for domestic electrical supply is now 120 / 240 volts, 60 Hz. at typically 200 Amps per house.
New/nearly new housing might be built with 200 Amps per single unit, but half the detached single family residences in North America are old enough to have 100 Amps (1970's) or only 60 Amps from the pole (like my previous home built in 1950). Updating them to handle a 40 Amp Type 2 EV charger involves fatter wire from the street, a new breaker box, etc. Also new supply transformers if everybody in an area upgraded in the short time period proposed for EV adoption. It's not as expensive as the new EV they want us to afford, but it's still a couple of months' salary per household to upgrade the supply in an older area. (edit: plus higher fire insurance rate because of all the people who think they can upgrade power themselves by just buying a new main breaker and adding a sub-panel...)
Im not a journeyman but Ive done plenty of my own electrical work. Really enjoyed this history lesson! Thanks.
130V has been used as well in Europe (up to 1958 in my case). That time they decided to pass nationwide to 220V while swapping every appliance to the new voltage (and sometimes by replacing the appliance or providing an autotransformer 130/220). Later the standard became 230V for mass production, UK passed from 240V to 230V and the continent from 220 to 230.
In the UK, the official voltage is 230V with a wide variance. If you put a volt meter across the mains, you will find that in reality it is a lot closer to 240V than 230V.
I know that UK is not part of EU any more, but when EU decided to have 230 V they also narrowed the max voltage to 6 % and min 10 %. So the max voltage is 244 V. Before it was 220 V for most countries and the tolerance was +/- 10 % which gives max. Voltage 242 V.
More lamps in parallel results in less resistance, not more. The power reduction with more lamps was due to increaed current draw which the dynamo and/or wiring could not support at 100%.
Ohm's Law strikes again! :-)
Before AC was used, streetlamps were even fabricated for voltages ranging from 100 V to 110 V. You would use lower voltage lamps near the end of the power line where the voltage was lower.
It was very interesting for me as an electrician to learn some historic background and some facts I never heard before. Thank You very much
Only the heating element in a domestic dryer required 220 volts, the rest of the dryer is 110 volts. That makes it easier to also use the same base model for a gas dryer.
Well
First, it is the other way around. You sit down, do the math, plan your specifications and device. AFTER that, the heating element is chosen/constructed/wound up. Second: heating elements are resistive consumers. purely ohmic resistances. The selection criterion for two or three-phase electricity feed is based purely on the required heat output, which is proportional to the needed current strength, which as well determines the needed line(electrical wire) cross-section. With phase-shifted alternating current it is also possible to use simpler and cheaper motors for the drum. With a star/triangle (YΔ) circuit you also get the possibility of easy temperature adjustment in the heater(think at a time before 1920! :) ), setting of the motor characteristics or easy power adjustment.
Trivia: Just do the math. Basic American Outlet, 110V x 15A = 1650W (vs. x2 or x3 or 1/3 with the same breaker/wire specification). My (German) transportable fan heater has more heating capacity:)
Dryers, irons etc all are over 2kW in Europe.
To deliver the same power twice the amps must be transported. Standard wiring would be thicker and too expensive.
@@Be-Es---___ I really can't understand why people write BS or waste our and their time with it?! In times of google and wikis. A simple search proves your first sentence wrong. A current has to be transported anyway and where comes that strange "the same power twice" from? The STANDARD determines which conductor cross-section is used. If your gibberish really means that a standard compliant line from plug to device, let's say 10A vs 16A = 1,5mm^2 vs 2,5mm^2 has any relevance in contrast to the device cost ... then I'll take you as a stand up comedian. A bad one ...
Details:
"To deliver the same power twice the amps must be transported." ... WTF? The same ... or twice? BS! ... its simply 2 * (V * I) if TWICE the power was meant, which translates for normal people as: The product of the two factors voltage and current have to be the double amount as before.
"Dryers, irons etc all are over 2kW in Europe." ... amazon says BS
"Standard wiring would be thicker and too expensive." ... Talking about "standard" wiring for any iron tells the knowledge of the writer. The "standard" there is heat-resistant cable with the appropriate conductor cross-section determined by the device protection
@@dieSpinnt Having lived and/or worked in many 240V countries , I will say there are plenty of common electric appliances which are fairly high wattage. A typical electric kettle (*very* common item in tea drinking countries) can be up to 3KW. Dryers not so much ... but that's partly down to Energy Star programs.
In the UK, wall outlets are usually rated at 13Amps - at 240V that's 3.1Kw - and we don't have special high-amperage circuits. So things like power tools etc are often designed to draw more power. Also very common in the UK are immersion heaters for water - and those are definitely 3Kw because I used to replace the element on mine routinely as we lived in a hard-water region.
Bart Sw's comment on "twice the amps" is correct, just badly phrased. To run a 3Kw heater from a 110 outlet, you need to draw over 27Amps and most US outlets aren't rated for that. So yes - keeping power constant ("the same power") and halving the voltage, you need "twice the amps".
Also, there's another major difference in the UK when I lived there - and one which has caught me out here in the US repeatedly. You NEVER run ceiling lights and wall outlets from the same physical breaker/loop. The ceiling light loops were each protected by a 5Amp fuse/breaker. That let you run up to 12 100W Bulbs per loop (and use less copper).
I was a little surprised by you mentioning transforming voltages in distribution systems before you introduced AC with Westinghouse at the Chicago Fair. The only real transformation option for DC electricity pre AC would have been highly inefficient motor generator units.
Agreed
It's 110V vs. 220V (past) and now 120V vs. 240V present day. The voltage was slightliy increased across the world. And there is 240V in every house in the USA. It's juat a matter of how you are connecting the local sockets.
Hi In the UK Joseph Swan is considered to have preceded Edison to develop a working lightbulb. His invention was based on a carbon filament rather than platinum by Edison. Many scientists around the world helped Swan and Edison improve the operating life.
Swan was before Edison before him there was a french man a Russian and a German that invited parts there is zero reason to think Edison invited anything and you have a bad electric system because of him.
@@alanrickett2537 it's always like that. When a technology is 'ripe' it gets 'invented' several times at the same time all over the world.
@@EVPaddy Yes then a SOB steals it and claims he did the work. An episode on the USA patient system before 1958 would highlight that china's not the biggest IP thief even
SIR Joseph Swan invented the electric light not edition, Swan sued edition for pinching his patent. They later joined to form the ediswan company.
Swan was born about a mile from where I was born! Yeah, nobody cares but it felt good typing that, lol!
Here in Spain, 110-120V was still around in some regions in the 80s, and in some rural areas, it continued into the early 2000s. If I understand correctly the switch started sometime in the 50s, so that means people would have had to use step-up/step-down transformers for up to 50 years, to be able to use their 110V devices on 220V, or their 220V devices in 110V, depending on the case.
I never saw 110V on the lines myself (I'm 37), but my grandparents still have devices that are 110V, which were made sometime in the 40s or 50s, and they have a couple step-down transformers for use with those devices, when they need them.
In the case of my grandfather, it's a drill press, with a relatively powerful drill, which would be too expensive to replace for the little work he does as a hobby.
In the case of my grandmother, it's a coffee grinder which she uses to grind sugar for use in baking, because nothing else she has tried leaves the sugar as fine and uniform.
Actually most AC line voltage in USA is not 120 v and 240 v, and 240 v at 60 Hz is delivered to every household with 3 wires instead of 2 so that the center tap of the output winding of the transformer can deliver either 120 v or 240 v to the appliances. Lights and most AC outlets are 120v and electricians try to balance the phases of the 240 v winding such that the neutral center tap carries little current. Electric hot water heaters, electric ranges, electric clothes dryers and central air conditioners are all wired with 240 v and you will notice that those devices have double breakers in the power breaker box so they get power from both phases of the AC secondary transformer winding.
I think this might be the reason why my country (Brazil) uses both voltages. Parts of the southern region uses 220v and the major cities use 110v. It is a big problem for appliances when traveling, in my home state you can find both, and in my house we have both, usually it's used for appliances which uses more potency such as clothing dryers. I believe parts of our electric grid were built from both British and American investments in the past, will have to look up now
Few regions in brazil still uses 110V, most regions nowadays moved to 127V, that's why we don't see electrical equipment classified as 110V anymore, they are either classified as 127V or 220V or fullrange which accept any voltage between 100-240V. In the state where I live the only available voltages for houses are 220V and 380V.
USA has both 120V/240V and has both in every home. Most homes just reserve the 240V to big appliances, but any of the circuits can be changed to 240V if desired.
In the US the electricity is primarily distributed as split phase. It splits a single phase at the transformer and the neutral is generated it the mid point of the split phase transformer. So the two 120 volt wires that come in your house are in phase. A single phase. The confusion largely comes from probe placement with an oscilloscope. We actually have 240 split phase service in most of the US
The two 120V half-phases are 180° out of phase because they are the created from each hot lead of the 240V. The neutral of the two half-phases is created by physically putting a tap in the middle of output circuit with the same number of windings from the neutral to each leg of the 240V. A single 240V phase is split to create two 120V. Hence the name split phase.
If you really believe the two 120V half-phases are in phase explain how a 240V curcuit breaker works. If the hot leads of both 120V circuits were in phase you would have 0V between the two half-phases. Get some extensions cords and test the receptacles in different areas of the house. You'll get 0V for circuits on the same half-phase and 240V for circuits on different half-phases. .
@@curtislowe4577 Does this mean you 'hookup' your stoves to 240V?
@@ianmontgomery7534 yes. American homes are 240V. Europeans largely believe Americans homes are 120V and they are not.
@@blueoval250 But most appliances still run on 120V while in Europe those run on 240V.
@@blueoval250 120 volts nominal voltage to earth/ground . . . not line to line - as that would be reflected at the full secondary voltage of 240 , whereas in Europe , Asia and parts of South America - domestic power is actually derived from a 3-phase power transformer with the secondary windings connected or terminated in a WYE configuration , with each secondary phase winding at a nominal voltage potential of 240 volts A.C. 50~ Hz . . . and the line to line or phase to phase voltage potential at a nominal 415 volts at 50~Hz
In the United States , Canada , Mexico and parts of the Caribbean Islands - the Single-Phase or 'Split-Phase' 3-Wire Transformer Secondary with the full voltage across the entire winding being at a nominal 240 Volts A.C. at 60~Hz and center-tapped to Earth/Ground (Neutral-Point) where each half of this secondary is now at no more than half of the full voltage potential to earth/ground and is also used as a circuit-ground or common/neutral conductor in order to carry the unbalanced or neutral-currents back to the power source (transformer secondary winding) where this circuit ground or common/neutral has been derived from in the schematic . . .
In a perfectly balanced 120/240-Volt 3-wire system - no current would be flowing on the common/neutral conductor , as both 120 volt loads on each end of the transformer secondary winding would then be operating in series across the entire 240-volt transformer secondary - since each opposite end of the 240-Volt secondary winding are effectively at opposite polarities from each other and the phase shift would then be at a 180-degree difference from each other , whereas the voltage potential across any one of these 'legs' (as they are called in the electrical trade) will not be anymore than half of the full voltage potential across the entire transformer secondary winding - the main reasons as to why this system is still referenced to as a SINGLE-PHASE system is due to the number of transformer windings on the PRIMARY SIDE of the transformer , along with how many primary power lines it is associated with in contrast to a bank of two or three transformers on a pole supplying a 3-phase service to a property or a structure - where at least 2 or 3 primary power lines are going to be used (as in that of a 240-volt open-delta 3-phase, 4-wire configuration that uses only two transformers and not three) . . .
Also bear in mind that a 120/240-volt single-phase 3-wire electrical service could and are often also derived from the same bank of transformers so connected in a 240-volt delta configuration - as the 208-volt high-leg would then be omitted from the scenario . . . Such as what would be found in an area where both commercial premises and residential premises are nearby and are sharing the same banks of power transformers . . . as what would be utilized for 240-volt services . . . Not to be confused with 120/208 WYE 3-Phase - 4-Wire service that would then need an entirely separate bank of transformers , since the phase-angles on all three phases would then be 120-degrees apart and each leg or phase would also have a multiplier of 1.732 for phase to phase voltage or by calculating with the square-root of 3 . . .
This story is great! Unfortunately for Edison, we see that he was not as big a genius as school textbooks say. A lot of different people of different nationalities have made bigger inventions than he has in the electricity stuff.
“Unfortunately?”
Oh, come now; let's get a grip. Edison's genius was not restricted to things electrical. His invention ranged across a wide array of explorations. I don't know what school textbooks say, but Edison's abilities were without question formidable and outstanding.
We can also say that full-heartedly without minimizing the fact that many people in many places are always behind any large-scale developments and advances. No one person ever does it all, even in a single discipline. There's plenty of room to recognize everyone's contributions.
The big mistake is to try to find "the biggest", "the best", "the most" among individuals. Each person adds a layer into a process, that layer forming a foundation for later ones, and itself resting upon layers preceding, and sometimes side by side with concurrent developments, all of which are building blocks. The overall picture is just as amazing as each individual piece.
Competitions are for the weak and insecure. Contributions are where the muscle and brains are.
@@farmergiles1065 that was really well written. The part about finding "the best amongst individuals" was deep man. Mad respect 👏
@@azorahai1135 Very kind of you to say so.
Edison was a very bright man, but Tesla was a genius.
110V system is outdated for North America. During my last years trip to Canada, I noticed that they have both 220V and 110V connections to homes! 220V for car charging, cloths dryer and other high powered appliances, and 110V for others.
It would be simpler with one system- 220V connection to homes, like how the majority of the world’s homes are wired.
You make an amazing number of factual connections in your videos and you’re engaging. Please keep em coming. Subscribed! Please don’t be afraid to show equations (even if you don’t dig too deep into them). I think you have a lot of folks watching that would appreciate it.
Until the 1930s there was a dizzying array of different types of power supply depending on where you lived. It might be AC or DC, the nominal voltage might be anywhere between 200 and 250V and on AC system the frequency might be 25, 50 or 60 Hz. This was because power was supplied by local generators, often owned by the municipal authority. However during the 1930s construction of the National Grid began and that distributed power at 50 Hz 3-phase AC. Local distribution was at 230V.
Because construction of the Grid was delayed by WW2 it wasn't until the 1950s that all areas of the country were connected to the grid and some local areas continued to have these non-standard supplies right up to the early 1960s. After WW2 the nominal voltage of local distribution was raised to 240V, but more recently it was notionally reduced back to 230V +/- 10%, but in practice supplies are usually still around 240V.
Great name
The US uses 240 split phase and run the individual 120v legs except for high demand applications such as ranges and dryers.
What an excellent explanation! We are waiting for your next video to know about 60 VS 50 hz
Very interesting video. Small correction to the multiplier of 1.72 you mentioned at 12:45: The relationship between phase-to-phase voltage and phase-to-neutral voltage on a three phase system is the square root of 3 or approximately 1.732. 120 x 1.732 = 207.84 so that voltage is called 208/120.
Don't forget stinger leg systems. 120/208/240vac.
the stinger leg 120/240 volt systems are delta connected and the 120/208 volt are connected wye. You get the stinger leg from three phase120/240 volt delta with a center tapped neutral. In San Francisco, the stinger leg was color coded purple or orange.
This is also called the dead leg
I have always called them high Lag delta
We DO use 220v, in fact in most neighborhoods the poles and ground systems carry 3 sets of 220v and we just use a trick to make it 120v. The power is distributed as 220/240v! Unlike most places that have 240v direct to outlets the US also has a grid that grounds out uneven soil charges to a distance. You can't do that reliably with 220/240v-only systems.
The US did settle on 230v and 240v, but it's split phase:) So my panel runs at 251v at 200 amps with 2 legs, each supplying about 126v at 200 amps.
Good point, and I was going to get into the whole split phase thing and then I realized it’s just too complicated and in truth what we get in our plugs is still around 120 V
@@Kathy_Loves_Physics Haha, lets confuse everyone and sneak in 3 phase 400 cycle power. Aircraft stuff! I worked as a Field Engineer for GE decades ago and flew all over the planet. Of the many gas turbine and steam turbine driven generators, almost all I installed or worked on were 3 phase 60 cycle wye connected that output 13,800 volts. They ran at 3600, 1800, or 1200 rpm depending on if they had 2 magnetic poles, 4, or 6 as used on many marine 1200 rpm generators. Nearing age 70, I still have more than a dozen working generators in my workshop. It's a hobby.
@@Kathy_Loves_Physics Plus if anyone wants to learn a bit more about it there's a Technology Connections video they can watch.
Fantastic video, Kathy! I really appreciate the amount of time and research you put in your work. It's always worth waiting for you, so I'll always like the video before even watching it! :D
wish you all the best!
Thanks so much Ruan. Will try to be better about posting more often but sometimes it takes me a while.
Fascinating! What I loved most about this video is that I got a bunch of interesting questions answered, which I didn't know had. Also excellent narration.
I love your enthusiasm Kathy, I've often wondered about this. Could you look at the development of underground transmission lines, and the move towards DC for long distance transmission?
i always thought that we were worried that 220 volts was too unsafe. although there's some argued that 220v was more safe because it would be more likely to throw you off of it. whereas 120 volts was more likely to keep your hand clinched and causing you to not be able to become detached from the source
Let me tell you. That's exactly correct. 120v is a deadly voltage.
is that true? that's really interesting .
i have zero understanding of how electricity works and i am terrified of it after almost electrocuting myself as a child . i live in Germany now and have this apparently incorrect idea of how dangerous 220 is ?
@@siriosstar4789 220-240 tends to knock you back. As stated above, 120, if you’re grounded properly, will literally grab a hold of you and curl your fingers around whatever you’re holding, making it next to impossible to let go. That actually happened to me once, and I was electrocuted for approximately eight seconds, before my boss came over and pushed the ladder out from under me.
On Friday, I was working on some lights in a car dealership, and as usual, I wasn’t being careful, and I got hit with 277 V. That hurts. But I’ve been hit by 277 many times. Most of us electricians are too lazy to go turn the power off. And besides, panel schedules are never correct. You could waste more time trying to find the correct breaker than repairing the actual light. It’s like a horse. You get bucked off, you get back on again.
@@siriosstar4789 you are so right!
Quite simplified explanation for general public. Electric power generation, transmission and distribution is trillions of dollars industry in the world. It can get very complex when you add billing meters and trading generated electricity. Good job and thank you for your efforts.
Love your enthusiasm and history lessons. School would of been so much more interesting with a teacher like you. Thanks.
Always great to have a new presentation. Learned a lot. Thanks.
You’re welcome
In the European Union the voltage is now standardised at 230v 50Hz.
( it used to be anything between 210v to 240v depending on what part of Europe you lived in.)
In your graphic there at 2:40 you’ve got it backwards. You’re showing lights in parallel, and the more loads you put in parallel the less resistance there is in the circuit, thus the more load the generator sees. That’ll tax the capacity of the generator, drawing more current and potentially bring down its voltage a bit.
You brought up some interesting historical points. I don’t know why you’d not mention Tesla, and his and Edison’s battle over AC v DC.
Yep, I noticed that was backwards immediately. The more "popular side" as she puts it has LESS RESISTANCE because the lights are in parallel. I find it amazing that at least 2 commenters claim to be electrical engineers and apparently didn't notice the mistake. It really bothers me when people talk about electricity and get things wrong. She did have the "less light" part correct, since the heavier load will bring down the voltage.
But at 5:00, now she's talking about transformers. Transformers don't work with DC. So she's mixing up Edison with Tesla there. I don't think Edison used transformers in his electrical distribution system.
Only commenting on the second paragraph. That story is fascinating and should have its own video. We were shown one i electrician school in Denmark but since it’s in Danish an English version should be made.
@@Hyxtryx you did have DC transformer also, but they are more complicated. Back then it was an electric motor coupled electric generator. In other word, not an efficient transformer.
There is a reason that AC gained traction.
It seems she addressed that already, there’s a card appearing at 2:33 correcting the mistake.
@@GRBtutorials No card pops up there when I view it.
I am very impressed at how you can gain all this history and just explain it to us with reading it all from cards! You love this history and it show. Thank you for the wonderful history lesion's and facts of our heritage here in the US.
🇬🇧As a 58 year old electrician, I thoroughly enjoyed this Thankyou. Amazing that due to the development of ultra high voltage solid state rectification, DC is now starting to be used for extremely long distance transmission, in some cases over a million volts DC. Search UHVDC transmission…….😊
Not starting , HVDC at 500,000 Volts , 2 wire has been going from The Dalles , Oregon to LA , California for over 50 years!
I wish English majors will stop writing books on Edison repeating that DC cant be transmitted long distance obsolete information !
I'm an electrical engineer. 20 years ago i asked the same question to my electrical machines profesor...that period when The USA selected 110 Vac was a time of paranoia and the US Gov thought the Europeans would flood the US market with european made 220 Vac appliances and Motors. So they selected 110 so the Europeans had problems producing both voltages appliances. He told me îs only for economical reasons although 220 V had economical design advantages.
And Europe also mandated that all machinery used in construction run on 110V... WHY? Fewer Deaths. Far more people per capita outside the USA/Japan and other 110V countries die than those running on 110V. As for the conspiracy theory baloney... What a joke, USA runs on 240V for all appliances/machinery just like Europe does and only ~kitchen handheld junk runs on 110V. Do remember by 1920's most electrical equipment was being produced in the USA and exported to Europe... Do remember in this period, there WERE NO household appliances worth mentioning other than Kitchen appliances and a radio which runs on lower voltage anyways so it is moot 120V/240V. Every country/empire had HIGH tariffs at the time. Something that should return. There was FAR more progress then as there were FAR more companies working on improving products and therefore for FAR more ideas entering production.
BTW, houses as in residential locations, especially single family dwellings DO NOT get two phases of a three phase system. They use TWO legs of 120 (from a single winding distribution transformer) and are provided with a neutral (ground). The result is 120 either leg to ground (or neutral) and 240 leg to leg. The phase relationship between 120 and 240 in the home is "0" degrees.
you are not an electrician right hahaha, sorry but 240V is a real thing ... your oven work with this voltage you dum dum , educate yourself
That's the most detailed description I've heard so far. I knew it had to do with Edison's 110V light bulbs, but that was all I knew. It was not only voltage, but frequency. Westinghouse favored 60 cycles while Siemens favored 50 cycles, so countries which bought American Westinghouse equipment standardized on 60 cycles and countries which bought Siemens standardized on 50 cycles. Japan brought from both, so they have an interesting mix of 50 and 60 cycles. Of course we have a few pockets of 25 cycle power, used for railroad traction power. Safe Harbor Dam still has 2 25 cycle machines to generate power for Amtrak. BTW the railroad uses 440V to distribute power on at least some of their trackside lines. I often see 440V written on the crossarms of open-wire trackside lines. Now we've come full-circle and DC has come back into favor, at least for some high power transmission lines.
I lived in Korea for several years where most homes have a transformer to change the provided 220VAC to 110VAC. The transformer was also the circuit breaker pane. All the appliances I saw in the shops were 100-120VAC.
Korea probably picked up the standard from the US. But rather than centeally breaking the phase into 2x 110v, it was done innthe homes and premises. I'm curious, what about 3 phase, as used in factories?
As a sideline, I work in Laos (a landlocked country between Thailand, Vietnam, zchina Cambodia and some others). Anyway the US Embassy rewired their buildings and part of that was to split the electricity phase into 2x120 (it may have been 2x115, I forget what the country ran on). It was expensive to do so, but meant that the staff can plug in their appliances without have to think about compatibility.
It is important to distinguish between RMS (or effective) voltage, and peak voltage when talking about AC. Your chart shown at 13:00 is not clear about what figure is being listed. The source for that chart in Wikipedia does not spell that out either. The number for the US (120V and 240V) are consistent with these figures being PEAK voltage. What is the difference? Peak voltage is just that: the maximum voltage in the Alternating current cycle. This is the voltage that the insulation on a lamp[ cord has to protect you against. The 'RMS' voltage is the equivalent DC voltage that would deliver the same power to a fixed load. It is less than the peak voltage (about .707x Vpeak). This makes sense. Most of the cycle the voltage is less that the peak, and drops to zero for an instant each cycle. Therefore, AC voltage is often expressed as a root mean square (RMS) value, written as V rms, because P=(V rms)exp2/R.
Absolutely correct. The peak voltage above or below the zero crossing point at 120VAC is 120 times 1.414 (or √2) is about 170V. One learns this in Alternating Current Theory AKA electrrical engineering 102.
Well, you got some parts correct. But most wrong.
The first two lines are for three-phase systems and it is the live to neutral and the other number is the phase to phase number both still in RMS voltage (how would I know that? The conversion factor is 1.73 or (SQR(3)). The third line is the split-phase system with a 180-degree phase shift, still RMS. The other two lines are single phases at higher voltages.
The peek voltage is actually 1.41 times the RMS voltage (SQR(2)) and the peek to peek voltage is two times that.
So a 120V 60Hz AC is 169.7V peek and 339.4V peek-peek voltage.
120V and 240V are RMS voltages, not peak voltages. Pretty much any AC distribution voltage mentioned is RMS, not peak. If you look at a 120V outlet with an oscilloscope, you'll see it going +/- 170V peak or 340V peak to peak.
Great content by Kathy.. Thanks to youtube for suggesting me your channel. Keep doing great work. :)
One suggestion you can show some important words/dates/milestone flowing on screen when you are on video, that would make this more interesting and catchy and this will go to larger audience.
America is way behind in utility power. In Greece everyone has 3 phase 380v in our homes including apartments. This means we have much more power available. Also with 220v all cables are thinner due to lower current draw.
Excellent video. Subbed.
Isn’t it ironic that we are far behind in America now because we were far advanced in America at the time?
The problem is that Greece is small in land size and population size than the US, it's a little bit smaller than the US state of Florida. The US is ~9.8 million km2 and Greece is ~131,957 km2. Population of US is ~329.5m and Greeze is ~10.7m. We also industrialized fast and early on. All of that means that what it takes to change us to 220/440v is orders of magnitude more complex and expensive. There was supposedly a plan to switch us after WWII but by then our grid was massive and we had so much equipment running on 110/120 that it wasn't economically feasible. Speaking of WWII, it was far easier for most of Europe to modernize because they had to rebuild after the war. The US mainland was barely touched during the war beyond Pearl Harbor and a few other isolated incidents. It's also a common misconception that US homes and apartments are only 110/120. What we actually have, and a correction to the video, is what's known as "split phase" not two phase. Our houses are fed by a 2x120v hot lines and a neutral. The 2 hots are fed from each side of the output of the transformer and the neutral/ground is center tapped on the transformer. Measured voltage between L1 or L2 and N gives 120v and between L1 and L2 gives 240v. Appliances with high power needs such as ACs, ovens, dryers, furnaces, heaters, and big motors can be fed by 240v via a breaker that spans both bus bars in the panel. Industry here uses 3 phase. No real need to supply a home with 3 phase. Computers, TVs, phone chargers, and most other devices use low current and don't actually run on 120v will have transformers and switch mode power supplies that drop the voltage down to some low voltage DC anyway. To be fair, I wish we did switch when we could and I wish we would phase out our horrible plug sockets to something safer like the UK plugs but I think we're decades past when that was possible.
@@Kathy_Loves_Physics It is, but that is the dialectics of lead. In every industry and technology it takes a huge leap to overcome that... if not it were ecomically unreachable.
@@LiquidPortalDigital Greece is part of the European electrical grid. Yes, it’s one. So Greece’s small size is not relevant.
@@tookitogo that's not fully the point. The point is that we're one single country that's very large and industrialized very early and changing our electrical infrastructure over for a high voltage is needlessly expensive and would probably take half a century. It's just not worth it. Any device that would benefit from the higher voltage can be supplied by it because our houses are supplied with 240v. If a commercial or industrial facility needs high voltage or 3 phase they can get it. Our infrastructure has problems but the voltage delivered to our houses is hardly an issue. Side note - Texas has it's own grid and it's a disaster because it's horribly under-regulated by their utility board.
Great presentation on the history of electricity. Thank you for creating a comprehensive and understandable video. Without intending to be critical, I think the video would be enhanced if there was less hand and arm gesticulation.
Agreed
I disagree. I wasn't even concious of it as I watched. I just got the general impression Kathy is speaking with a general degree of enthusiasm. It is important for any presenter to appear to have a genuine interest in what they are saying, or the whole presentation becomes mind-numbing, regardless of the topic. Kathy, I thick your style is fine, don't worry about it.
I have an alternate theory, centered around the relative wealth of the USA vs. just about everyone else. All things being equal, lower voltages are safer than higher, but lower voltages need much more copper, which the USA had plenty of. Also the USA was energy rich, whether it was coal or oil. This also removed any incentive to maximize efficiency, unlike in resource poor Europe. In a similar vein, 50hZ is slightly more efficient than 60hZ, with the disadvantage being the transformers and motors require more iron. But iron is cheaper than copper.
Some of this makes perfect sense on some. but huge assumptions on others, I love that no one brings up the fact that Edison was in patent courts as much as he was in labs, and many of "His" inventions were litigated. Similar to many other inventions at the time, and we know how much of a sport he was, see (the current wars and the stunts), etc. I get the definite feeling that like a certain fruit named "inventor" (SJ) a great salesman rather than great inventor would be more fitting, and like our modern hero, technologies and technological innovation drove the "invention" (I know they would never get that rich selling the computers).
I think history does a great injustice to the steps, that drive invention (materials development, physics discoveries, and disconnected science that bring about invention) in some cases luck. but I loved the piece and learned something new today which is always great
Edison's biggest contribution to invention might be industrial-scale R&D. He could brute-force invention by finding good engineers who had the potential but not the resources to invent and hiring them into well-equipped workshops, backed up with lots of technicians to do the time-consuming work of construction. A great improvement on the old approach to technological advancement: Waiting for someone wealthy enough to do it as a hobby.
He did cultivate the image of himself as the super-inventor though. He knew the importance of branding, and put his name on every product his workshops produced.
@@vylbird8014 patent trolling too, again marketing was part of his "genius" same as Steve
History has indeed been cruel to the true inventors and innovators. Worse than that is that falsehoods have been perpetuated in schools and have served as inspiration to contemporary scallywags such as the recalcitrant individual to which I believe you might be referring.
No not trolling, being honest, Steve had some stinkers that fan boys love to forget, and technology grows slowly with big jumps occasionally, if I was to congratulate him on anything sales, salesmanship and marketing, tieing the price of iPhone in with the phone contract was genius, but inventor? (which the discussion was about?) Bell invented the telephone? Or Marconi the radio? It's why I love this channel and others.
I love it that at the video she did give it a subtle blow to Edison with the quotes on "invention factory" at 1:15