@@EverydayHomeRepairs We in europe don't have any of that we just plug things in and don't care if its reversed or not, we are just careful not to touch any metals, then again if I do touch metal, our whole house has GFCI protection instead of just a few sockets in the kitchen/bathroom
Here we go again. Where were you when I had this problem. I was selling a house and the inspector caught this problem in the bedroom plug. I tried to fix it but without any luck. I called an electrician and he had to trace the problem all the way to the bathroom switch. So the problem could be different than the plug itself. The house was fairly new and I wondered how so many inspectors missed this problem starting with state inspection. Well explained and thank you for sharing
As someone working in residential housing construction as an electrician, it's a horror show. The inspector does not inspect everything. Sometimes my coworkers run out of weather resistant gfi plugs, so they use the normal ones in an effort to fool the inspector, knowing he won't check. Many don't even understand basics and don't utilize critical thinking because they take a completely procedural approach. They don't need to know how everything works they just need to know how to put it together. Everyone comes under the impression that the world has rules that must be followed, but honestly, it seems the are a lot of people in society who just.. don't care. Not out of malice, but pure apathy. Almost reads like exhaustion. And yes, I'm trying desperately to get a new job, it's just really hard.
@@Rin-qj7zt wow. You just described the reality. I have leased a gas station once and few months into the business my A/C started to act up. I called the pros and sure enough he found a cluster of live wire pointing up without caps. He could have easily touched them and hurt himself. The building was almost 2 years old and just disgusting to see violations passed by the inspector. I wish you luck in your future job
Good explanation! I think you covered two of the three big topics: outlets, light fixtures, but also switches. If your light fixture is wired correctly, but your switch is wired incorrectly, I think you end up with the same problem. In particular, many people will do fixture work by flipping the switch off because they don't want to deal with the breaker, but if the switch is wired backward, you can still have hot waiting for a path to ground all the way at your work.
I came here to say this. Having a lightbulb with its threads exposed is a good example of something an everyday homeowner (or their kid) might do and not consider it in any way dangerous. But a DIYer trying to change a light fixture with just the switch turned off and not the breaker? That's a nice, educational shock for DIY electrical work. It doesn't matter if you know what you are doing, get a voltage tester or a mulltimeter to check for voltage before you touch ANYTHING. If I don't want to play the breaker guessing game then I will tape the light switch in the off position. That way all of the people I tell not to touch the switch will have a second warning before I come down the ladder and dole out some verbal education.
THANK YOU SO MUCH!!! I struggled to find an explanation as thorough and easy to grasp as this one. I always was taught, heard, and knew it was bad if you reversed polarity, but outside of frying your plugged in device, I never really knew WHY it was bad. This demonstration with the bulbs, the way you showed how you could shock yourself, and the way you explained it, finally has given me the WHY it’s so bad! I’m definitely saving this for future reference.
My daughter recently bought a house, which was inspected and the inspector found reverse polarity on one of the receptacles, which had a lamp plugged into it. She did not understand why this was unsafe or why it had to be changed. And I explained it much the way you are. Thank you very much.
Years ago I tested the receptacles in the kitchen of a friend's office building. Sure enough one "neutral" was hot. The electrician got there is record time. Thanks. Glad I subscribe.
I have seen this in many homes. The homeowners don't seem to want to understand because they have to pay me to correct it. So, once I explain in great detail, they finally get it. I have seen more lamps that homeowners have rewired on their own, with reversed polarity than the light fixtures. Great lesson for homeowners, you did a good job!
Quite frankly if you're touching the lamp base and get shocked then you deserved to get shocked. Unless you're trying to change a busted bulb. I've heard a tennis ball works for that. But if the bulb is intact there should be enough insulator to grasp.
I'm just a homeowner, without a great deal of experience doing home electrical wiring. For example, I knew that reverse polarity in a outlet was bad for the devices, but I didn't know why. And I had no clue about reverse polarity in light sockets. Which makes this a timely video for me, because I have a light socket that is old and I need to replace.
I am working in a house that was built in 1947. All wires look black. This video prevented me from possibly wiring a new fixture incorrectly tomorrow. So easy to check with just non-contact voltge tester.
if you look closely, one of those wires will have a white or silver stripe on the side, although it may be worn away by now. BTW, if it looks like cloth covered romex and has a light silver glaze on the outside, it's impregnated with arsenic (poison) to keep mice from chewing on it. IOW, wash up after working with it.
@@rupe53 Thank you for the arsenic warning. It is "cloth" covered wiring in conduit on the main floor. Unfortunately, it is in BX behind plaster and it is not feasable to replace.
I recently received my Journeyman license and I can say that this is a great explanation on why the polarity is importantant in the wiring. Thanks for the video.
@@EverydayHomeRepairs any recommendation for testing reverse polarity in light fixtures where there isn't an easily accessible ground? Taking a light fixture down to check wires seems tedious when checking every fixture
@@lumby1412 You can get a polarity plug in tester, like the 3 plug type, and get a test kit from home depot that has alligator test leads, or lightbulb plug on it where you can put them on the "assumed" hot and neutral, and see if it lights up right on the tester.
I moved into a home a few years ago that was built in the late 1960s. I didn't realize that several outlets had reversed polarity until I was swapping in some smart plugs. Then, I took my tester around and found the others.
I purchased a rehabbed house over a year ago and I just found out that the receptacle for the garbage disposal was wired backwards between HOT & NEUTRAL and I found this out with my Fluke ST120 socket tester. For the longest time, the circuit breaker/GFCI would periodically trip and I do believe I just found out why this was happening because of reverse wiring of the garbage disposal receptacle... THANK you so much for these videos.
Thank you. I have an old lamp with a two-pronged European that my mother has working with adapters. I am rewiring it for aesthetic reasons, and I can now wire it safely since it will be in my daughter's room. Great video and great explanation!
Well done explanation. This is why you never use a POTATO to unscrew a broken light bulb. Most older homes have the neutral switched and a potato is mostly WATER. Turn the breaker off and use a pair of insulated needle nose pliers to extract the base.
Good advice. I have used potatoes for unscrewing broken light bulbs. Including for a 150 watt high pressure sodium bulb in a yardlight that was busted from being hit with a football during a party. I was depending on the photocell not to kick on, super dangerous because of the high voltage ignitor, (2500 to 4000 volts) found in all high pressure sodium and smaller (150 watt and under) and many newer metal halide fixtures (pulse start metal halide)
If UA-cam videos could be rated five stars this would be a genuine 5 star video. Simple, to the point with well explained examples of how to tell if the wiring in your house is suspect. I totally expect your subscriptions to increase if you keep this up!
another note: older homes with knob-&-tube wiring, the neutral is switched, common practice at the time. when replacing a ceiling fixture, turning off the circuit is the best policy. fixtures is the same era with pull-chain & turn knobs, switched the screw shell or neutral.
I’ve lived in a variety of houses in different states. I’m always amazed what is not wired correctly. I would recommend a session on aluminum wire and Alcad sockets!
If you have aluminum wiring in your house, have it replaced ASAP! Aluminum wiring just doesn't conduct well enough for use on mains voltage. This is one hell of a fire hazard!!!!!
@@markrobinson8539 Not always. General rule of thumb...yes. An example would be a light fixture like shown in the video but it is 'fed' at the fixture with just a 'switch leg' ran down to the switch. This would see the 'hot' fed down to the switch on one leg and back to the fixture on the other. Not typical in 'new' construction (with free access to open stud bays and the freedom to run what is 'easiest' and needed) but you'd be surprised how often it can be required in rewires or simply just adding a switch to a light that previously was on a pull chain. Code 'allows' for this...so never just assume that black=hot, white=neutral. It may be true more often than not....but it isn't a certainty.
YOU ARE SPOT ON FOR EXPLAINING THIS!! IN THE 1950s ERA MY DAD WAS AN ELECTRICAL ENGINEER WORKING CIVIL SERVICE FOR THE NAVY! IT WAS AT THIS TIME THAT THE 3 RD PRONG SAFETY CASE GROUND SYSTEM CAME OUT AND HE WHOLEHEARTEDLY SUPPORTED THIS, AND CONVINCED THE US NAVY TO MAKE IT STANDARD SAFETY PRACTICE!
That light bulb example was excellent. I replaced a vanity light above a bathroom sink at an old cabin a few years back and it was not clear which wires were hot or neutral and I didn't have any testing equipment handy. I guess I had a 50/50 chance. Your test was perfect.
This is a very good instructional video. I would like to add that if you remove the bulb, screw in a make light socket to 2 prong female adapter then insert a 2 prong male to a 3 prong female adapter then insert a Receptacle/GFCI tester only the “open ground” light condition will illuminate. I purchased the Klein circuit breaker “finder” and I also bought the accessory kit to identify light sockets and switch circuit breakers. If there are 2 fault conditions present such as open ground AND reverse polarity the 3 prong tester only shows the open ground condition. It will not toggle between both fault conditions. This is also true if you have both on open ground AND a reverse polarity on a receptacle. Only the open ground condition will be displayed. Once you “fix” the open ground then the reverse polarity fault condition will be displayed. I like this video - I was just attempting to identify if my light sockets were wired backwards and the Klein receptacle tester will not allow me to do that.
I was recently installing new wall lanterns on my home when I came across one of the old fixtures wired in reverse. I guess the electrician was left handed because he turned the wire in the other direction. I saw that and wanted to be cautious so I checked with multimeter and found that the wire was still hot after the switch was turned off. Always good to check.
Excellent safety explanation. When I had to re-do the electrical in an old home that we bought, I found some of the light fixtures were not wired properly. Apparently, I was told this type of thing is not uncommon with light bulb wiring. Our home is now normal for the electrical safety.
The ceiling fixtures are most dangerous because you are usually on a chair or ladder changing a bulb. Getting zapped may not injure you, but falling off a chair could have very bad outcomes. Old school metal recessed cans are grounded. Even brushing the springs or clips that hold the baffle in place have given me a zap before I finished screwing the bulb in. I'm guessing that was the easiest return when the threads were live neutral was switched off.
I honestly didnt know the reasons why you dont want reverse wiring but when im wiring in my house I alway make sure its wired correctly, But at least now I know the reasons behind why you want it to be wired correctly. Its really good information and ill always keep that in mind when im working with older houses that arent wired correctly.
Thank you for this information. I was just recently replacing a burnt out lamp fixture & this information is going to help me from burning it out again. Again, thank you very much.
Many a Time when there was no outside receptacle and I couldn't get inside particularly with an older main panel, I would open up and attach a lead of a wire to the hot & another lead to the neutral bus- bar to run a skill saw. I never did make a jumper cord up in such a way I could plug a tester in and see if I had the hot and neutral reversed but I knew it would still work, although it's not 100% safe to do that without verifying that you have the hot and neutral hooked- up correctly.
This is the kind of stuff that should be taught at school level like so many other subjects that are critical for everyone when they reach an age that allows them to muck around. I hope your excellent video will get to be watched by as many people as it possibly can. Thanks for posting!
I have recently watched lots of your videos, and they are informative. I am a beginner in DIY projects and want to learn more about how to do more DIY. Thank you.
I've seen the neutrals being switched in lighting circuits MANY times, especially in older homes. Never assume that power is interrupted with the switch in the off position; check it with a meter before doing any work.
OR JUST PULL THE FUSE OR BREAKER or do you trust the electrician? The wrongly-wired hot or live light fitting with some low energy bulbs can be enough to cause them to gently glow when switched 'off' and work fine when 'on' !
Hello Mr. Everyday Home Repairs, I am glad that UA-cam recommends your channel to me. Your explanation of the electricity is very simple and clear to me. This helps me a lot if I need to fix things around the house. Thank you.
I think the previous owner of this 1960-era house did much of the wiring himself when it was built. About half of all of the outlets (that were polarized, 2 or 3 prong) had the hot and neutral reversed, and half of the bulbs had the neutral line switched. There were also plenty of the 2 prong non-polarized outlets all over the house.
My dad found most of the outlets were wired in reverse in an older house that we moved into. Being an electrician, he fixed all of those. But I would not have guessed that unscrewing a light bulb would zap you. So now I know.
The Edison screw (which is what you would consider a standard light socket) was developed quite a while ago. The polarized plugs and sockets used today were an attempt to make the Edison screw safer. The intent is for the large easily touched screw portion to be at neutral, while the hot portion is the little contact at the center of the bottom on the socket. (The easy to touch part = neutral, while the hard to touch spot = hot). Frankly, if the Edison screw were to be developed today, it would have been immediately rejected due to safety issues. But given how long ago it was developed, and how many of them have been installed over the years, it's a legacy device that's virtually impossible to get rid of.
@@johncochran8497 you backwards, smaller screw for less current as neautral is a traveler conducter carries 50% of of the curent line , if add both togeatherif current line is 120 v ac and neautral line is 60 v ac = total 180v ac. From ground to neautral is 60 v ac if curent line is being used. The curent line and ground be 120 v ac. Only earth ground is 0 v ac
@@michaelspencer6523 You might want to try again there. Your comment was rather incoherent and wrong. Perhaps you've confused about an Edison Screw vs an Edison Circuit. Even though both use the word "Edison", they are NOT related except in that they're both associated with electricity.
Electricity is the only thing that scares me doing little projects around the house, i don't know enough about its principles plain and simple. So videos like these help me a lot. Next up for me incidentally, is to put an additional outlet behind my alarm box so its power cord isn't exposed and dangling a couple of feet from the original outlet. Not sure if its a good idea or not, need to watch more of your videos for sure. At any rate thank's for taking the time to make and share your videos, i find them super helpful.
Very well done. This shows very clearly why polarity matters on grounded AC circuits. It's all in where the switch lies in the circuit. Very similar concept to why we always disconnect the negative terminal on a vehicle battery - there is less room for unintentional shorts. Again, very well done.
Great video. I would also recommend that people who move into a new rental or house check all plugs with your simple 3 light tester. easy to do and doesn't take long. Check lights before changing a bulb. On an old house I have run across a random plug or light that was mis-wired before I moved in. Always check ceiling fans and lights before replacing bulbs or doing maintenance on or replacing the motor. I have found these are mis-wired about 15% of the time.
This was super interesting and valuable to watch around unsafe vs safe connections: more videos comparing safe and unsafe situations around the home would be awesome!
Great mix of theory and application in these videos. As someone new to this kind of work, it's great not just to learn what to do, but why it works. Thanks!
Something very important to note about basic plug-in outlet testers: if the outlet is not grounded, they cannot detect reverse polarity. I learned this when my parents bought an old house and asked me to look over the wiring since I’m handy with that sort of thing, and many of the outlets appeared to be ungrounded but otherwise okay to the outlet tester, but when I used a three-prong cord plugged into a known good outlet as a ground reference, over half the outlets in the house were not only ungrounded, but the polarity was reversed as well.
It's amazing what you find in older houses. I have no problem with DIY work, I do it all the time myself, but do your homework and take the time to make sure it's right if you're going to. As my father used to say "if it's worth doing at all, it's worth doing right". I am in an older house, not that old but old enough for the kind of house it is and every 10 minute project turns in to so much more because someone did something wrong to begin with. I'm also a perfectionest so even if it's a minor thing, if I let it go it will annoy me until I go back and fix it.
Super helpful. I knew reversing hot & neutral was bad, but never had an explanation for why. It was particularly helpful to see the explanation about a device with a resistor. We had a ceiling fan with a remote burn out, where the control unit just melted. I couldn't understand why, and I think that's probably it. I'm checking that right now.
Best timed video. Exactly what I have been wondering since the weekend when I changed out a 3 way switch. I did not know which was hot and which was not. Thankyou!
Outstanding, I’ve had a number of cases like that and had to do the repairs that home owners just didn’t realize the hazards they could have exposed them selves to. Great job, keep up the good work
As always you taught me something today. I have a great respect for electricity and slightly frightened by it. However, you have taught me so many things by your videos, I would rather hang a ceiling fan than put in a new P trap. At least electricity is logical. Thank you🙂
Lol Why is a P trap not logical to you? The water it keeps in it keeps the sewer gases from your septic or sewer system from coming up through your drains. They can be toxic if you smell them over time… Google the issues with drug addicts fermenting their poop and huffing it. Gross, but it shows you why you really wanna block those gases from coming in the house. Plus, it can catch things like rings if you drop them down the drains.
The problem with reversed wiring also applies to re-wiring of table and floor lamps, something an amateur is more likely to attempt - and get confused about.
Absolutely. If you change a damaged cord on a lamp, throw away the old unpolarized plug and use a new polarized one and make sure the wide prong is wired to the socket and not the spring in the center of the socket.
Just a few days ago, I just electrocuted when I placing Lamp for testing.. The hot is the outside of the E27 Cap So I got mad and went to check the person that install the cable.. 😒 But then I realize that I'm the one that install the cable..
@@XanderProduction It could be miswired where the outside wire comes into the fuse or breaker box. If that is the problem, short of having the electric utility come out and pull the meter so you can fix it you are stuck with it. Don't automatically assume you made the mistake. Check it but if it looks correct to you start investigating at the breaker and then where the outside service connects to the main breaker. In Michigan code requiring that the line and neutral be connected "properly" didn't hit the state electrical code until the 2000's.
@@mharris5047 ._.)/ You're correct about the regulation.. But I live in Indonesia.. It's actually me who make the mistake, bcoz I'm the one who check the Live-Neutral but misplaced the connector..
Reversing polarity is more dangerous on a plug than a light fixture unless you have a plug wired after the light fixture but it should always be avoided just the same. This was a good and valuable video. I have a 2 year degree in Electrical technology and so far all your electrical videos have been spot on. I also had 40 years working for a regional water authority, 20 of them as an inspector, and know more about plumbing than many plumbers. I have caught so called professional plumbers screwing things up and doing shoddy work. The problem is especially acute when the licensed professional sends a journeyman without checking their work. I have literally had to show some of them how to accomplish an unusually difficult task.
Interesting. I did not see that coming, but I experienced it with a lamp years ago. I was taking out a lit bulb from a lamp and received a mild shock as I was turning when it turned off. Now I know why.
You should never touch the screw. If the bulb has broke off so that you need to use pliers then use special protection. In case of a plug in lamp unplug.
Actually I never said it was broken, nor was it actually lit. I mis-remembered it which is why I remembered it at all, as pointed out in the video, you should never be shocked by a correctly wired bulb.
I understand that with a reverse polarity on a light bulb that one could still receive a shock from touching the bulbs threads even when the light is off. How would one test a light fixture for correct polarity besides screwing in an adapter and inserting a circuit tester? Great job explaining this occasional problem.
There’s nothing wrong with screwing in an adapter and using a tester. Alternatively you could (carefully) use the test leads of a multimeter. Or more safely, use that in conjunction with the screw-in adapter.
Great job showing how to test the outlet with a tester. But it’s also possible to use the same tester to test a light socket. You just need a few more pieces to connect as follows: Mount an outlet in a box and add two male cords. One cord is polarized two pin and connects to the outlet at hot and neutral. The other cord is three pin and ONLY connects to outlet ground. Then plug outlet tester into outlet. Plug a polarized light socket to outlet adapter into the light being tested. Connect this whole device up using the two pin cord to the light socket and the three pin cord to a known good grounded outlet. The outlet tester will report if the light socket is reverse polarity. I’ve done this test at many houses and most older houses have reverse polarity lights. My own house built in 2004 has half the lights wired wrong. And that’s by a professional electrician and passed inspection.
or in a house that is new enough to have a grounding conductor, plug a grounded extension cord into a known good receptacle, and use a continuity tester to check between the ground pin of the extension cord and the screw shell of lampholders. or hold a non contact voltage tester to the screw shell.
Great explanation on how to use the Klein tester and also the probe. Your example explaining what happens when wires are reversed with a light bulb s an eye-opener! Yikes! Thank you. Much appreciated.
If someone theoretically completely scrambled up the wiring so that the ground and neutral wires were actually connected to 120VAC, and connected the hot to ground, the outlet tester and DMM testing would show everything is just fine. This is where a non contact tester would be helpful to identify this odd situation, as that would easily pick it up. If you're up on a ladder and didn't have any known ground reference, the NCV is a good confirmation to have along with the other tools.
This condition actually happens more frequently than you might think. In an old house that was originally wired with 2 wire ungrounded circuits and two prong outlets, sometimes 3 prong outlets are installed without providing a ground wire. In order to fraudulently pass a home inspection and make a 3 light tester indicate correct wiring, a jumper wire is inserted between the neutral and ground screws, aka bootleg ground, or false ground. If there is also reverse polarity, you have a reverse polarity bootleg ground (hot connected to neutral, neutral and ground pins sitting at 120 volts to ground potential) tester will indicate correct wiring, and most if not all appliances will appear to work properly, except a device with metal housing and a three prong plug will have it's case live. And with the possible exception of sensitive electronics, most devices will work without problems, if the polarity is reversed, just not in the safest manner.
Owner of a 1913 house here with a lot of original wiring. All the switches/fixtures are wired with a switched neutral. Supposedly at the time they thought it would extend the life of the switch. I got a small but painful shock changing a light recently. Now I am very carful or I turn off the breaker.
I had this problem working maintenance in a restaurant with a warming cabinet. The wires were actually swapped in the breaker panel. Employees were complaining that they felt a 'tingle' when they touched the cabinet. The entire cabinet was energized all the time.
I work as an electrician as well. One of customers gave us an antique light to install but the wires had no indication which was ground, neutral, or hot so ended up pulling my meter out to figure the three wires and hook it up correctly using the ohm setting.
This condition can be found more often when repairing a table lamp. The lamp cord used to wire table lamps and some multi bulb ceiling fixtures has a identified conductor unknown to most DIYers. A close inspection of the lamp cord would reveal a rib molded into the entire length of the cord over only one conductor. This is the neutral and would go to the shell of the bulb socket. Lamp socket/switch combinations do go bad occasionally and need to be replaced. Look for the identifying rib on the lamp cord and make sure it is attached to the shell of the socket. Sometimes the cord manufacturer will stamp the information about the wire in the insulation instead of the rib. This will also favor on conductor over the other. Again, this is the identified neutral conductor and should attach to the shell of the bulb socket. Another great video.
I work on a lot of old houses in the Denver area and I found another issue where they ran the hot wire directly off the breaker box to the light fixture,then to the switch, and then from the switch to common. So you can turn the switch off and there's still power at the fixture.
Same here, ran across that a few times as I was helping my step dad rewire his 1973 double wide, which had numerous problems with the aluminum wiring including a metal junction box concealed in the wall (highly illegal and dangerous, for those aware all splices must be accessible meaning it cannot require removal of the building materials to access) that had overheated to the point of charring the stud. I am not a big fan of this fortunately the code required a neutral be present in a switch box since 2011, making this wiring configuration virtually extinct, the only legal today, is to run 14/3 NM from the light to the switch box, which is pretty much pointless 99% of the time.
I remember back in the early sixties, wall sockets were usually ungrounded although polarized, however, the plugs were neither grounded nor polarized (two prongs, both the same width).
I just moved into a new house and found several outlets with reverse polarity, open ground, or no power at all. Checking the circuit breakers, the legends were all obscure and had to trace the entire house to correct. I am a licensed electrician and that was the first thing I checked even though the inspector failed to identify these issues.
When you're outdoors it is easy to inadvertently come into contact with the ground. When you do then you're electrically grounded. We use a ground reference for safety but the fact that we do creates a local hazard. Basically if you have to mess with electricity outdoors be careful and try to wear insulative footwear. You do not want to be in the return path for current.
Another thing that you need to look out for is when the switch is beyond the fixture. Ex: Power comes into a ceiling light fixture. The hot lead (black) should be connected to the black lead going to the switch and not to the black lead going to the ceiling lamp. The neutral (white) coming back from the switch is now the hot and should be marked (usually a wrap of black electrical tape) and attached to the gold colored terminal or black lead of the fixture. The neutral (white) of the power supply cable is then connected to the silver colored terminal or the white lead from the fixture. Many DIYers get this messed up.
Man thank you so much for your video. In 10 minutes I learned more than I had learned and understand about wiring issues 😅. I’m definitely subscribing!! Thanks again
This is why you should hit the breaker before working on a light, if somewhere along the way the polarity was reversed, the switch being off will not help you. I always check and recheck with a dummy stick (hot and neutral) before I go to work. 99.999% of the time it just scares you sometimes it hurts a little bit and it could kill you.
Sometimes a neutral or two from a different circuit might be in a box. It won't set off a non-contact voltage detector, but could give you a serious belt if you separate those "return" conductors.
@@thomaspierce9458 I see that happening, but it would be a perfect storm. also a neutral from a different circuit should be accompanied by a hot from a different circuit, which would be detectable. Once when I was really stupid, I got zapped three times, before I decided I would just hit the main, and avoid a fourth zap.
Good warning video that should be followed by home installers. Greetings from UK where we do everything different (mostly). For a long time, lamps here have used a bayonet cap, not screw cap, but they can suffer from indentation of the contacts. I am, (like more and more people here) now using ES27 and ES14 lamps as in the USA as they are better. I always double check the cables to ensure that the live (hot) line does go to the centre contact as in your video. For all practical purposes, outlets have to be tested with a proper device similar to the one that you demonstrated, as the contacts have shutters to prevent anything being pushed in. For my most recent home installation, I have upgraded to a Martindale tester which also measures ground loop impedance. I have found some incorrect wiring in our new home here and have since corrected it, but the worst that I have ever seen was in a house to where we moved in the 1980s. The metal frame of the kitchen 3-spotlight unit was connected directly to the (always on) hot supply instead of ground. I have long suspected that this may have been the cause of the previous owner's death, rather than "heart attack".
Almost 2/3rds of my house is wired like this. Built that way. Not to mention a million other crappy shortcuts taken throughout. But it amazes me at the box everything appears correct. 🤷♂️ I can only assume there is a junction somewhere that reverses (somehow) and continues on. I only found this out when I started the process of updating fixtures, switches, and outlets
Simple rule of thumb... DON'T TOUCH the electrical metal doesn't matter if it turn on or not. Just like even if a gun is unload, you don't point it to anyone's head and pull. Always consider it is live or loaded. Even with the light out I'm a bit concern touching the metal contacts. Never know if there is a cap in there that still storing charge. If i care i would short it out and than touch. But just don't touch is simplest.
I had a reverse light bulb socket, I actually found it when I installed an led. I have almost switched all my bulbs to LED, but the fixture in question I noticed a very soft glow when the switch was off, it was such a low amount of output that almost all other light sources had to be off, so I put that led in another fixture and did not have the same symptom. I actually discovered it was backwards at the switch, which meant hot was always hot, but still hopefully that’s useful information to someone
That glow is caused by capacitance between the wires. You can get it even without a reverse switch but that does increase chance of getting it. Better bulbs have methods to prevent that. U just shows how sensitive the bulbs are. A common method of wiring a switch is to draw one cable from a junction box into the switch and use the neutral as the return. The two wires close together create a capacitor that passes some AC.
Some older devices - like radios from before 1960 - can be very dangerous with a reversed outlet since the neutral line of the plug was often connected to the chassis. Plug it in backwards (this was before polarized plugs) or into a reversed outlet and the chassis is hot & if you touch a metal part of the case you’ll get a 120V shock.
@@janee7995 Those old electronic devices with tube amplifiers often had the chassis connected to one side of the line, as you correctly said - but not only in the USA. They would be made this way and sold in Canada as well. (I had a few shocks putting the tone-arm on a record.) If tube filaments were in series, this would also happen in other countries with different supply voltages - and no neutral for a return as on the continent of North America.
Those have unpolarized plugs unless modified. I consider those unsafe. period. Note with an unpolarized plug there in principle is no wrong way. It was seen acceptable that the chassis was hot. In Europe they cannot be plugged into grounded sockets as that would be too dangerous if you had a grounded computer next to and there is no legal way besides an isolation transformer to use them.
@@thomaspierce9458 Those were made in most countries. The difference is that in Europe the plug does not fit into grounded sockets so you need to do something really stupid to use them.
believe it or not, kitchen counter appliances were also non polarized back then and everyone had that spiffy looking chrome trim along the counter edge, which could easily ground against the side of the electric stove or the sink. I can't tell you how many times I got a morning wakeup call if I leaned against the counter with a small gap in my bathrobe while making toast! (not what you think because I was shorter then)
Thank you. For an Alternative Ed High School class, I worked up a board to show what happens in parallel and series circuits. It was interesting to see what happens with varying the bulb wattage in both types of circuits. The same kind of board could be used to demonstrate three way and other switch combinations as well as the impact of a dimmer switch. Explaining what happens in that type of circuit would be informative too. Thank you for your clear narrative.
An additional comment --- when checking voltages with a DMM, always reference to a known ground. Some may assume that they can check voltage using the Neutral as the reference but this could lead to incorrect readings with AC voltages if another fixture in the circuit is incorrectly wired. Also check BOTH Hot and Neutral during the same test.
I got some outdoor plugs in new place I bought that worked with the old bulbs put don't like LEDS for some reason. The LED's have power but flicker like a strobe light. I'm going to check for reverse polarity.
Great information, well explained. Can you do a video on deleting a switched outlet, changing it to constant power, then utilize the switch to operate a ceiling fan/light combo? Thanks
Best description of this problem that I have seen to date. Very clear and concise, easy for the layperson to understand. 👍
Thanks John 👍
I completely agree with @john jones
What a great video !
@@EverydayHomeRepairs We in europe don't have any of that we just plug things in and don't care if its reversed or not, we are just careful not to touch any metals, then again if I do touch metal, our whole house has GFCI protection instead of just a few sockets in the kitchen/bathroom
@@BartvandeMosselaar Bad idea. What if the GFI is faulty? The job should be done right or not at all.
Here we go again. Where were you when I had this problem. I was selling a house and the inspector caught this problem in the bedroom plug. I tried to fix it but without any luck. I called an electrician and he had to trace the problem all the way to the bathroom switch. So the problem could be different than the plug itself. The house was fairly new and I wondered how so many inspectors missed this problem starting with state inspection. Well explained and thank you for sharing
Good point Hassan and thanks for the example. I think many are caught off guard on what inspectors do and don’t find during the inspection 😁
As someone working in residential housing construction as an electrician, it's a horror show. The inspector does not inspect everything. Sometimes my coworkers run out of weather resistant gfi plugs, so they use the normal ones in an effort to fool the inspector, knowing he won't check. Many don't even understand basics and don't utilize critical thinking because they take a completely procedural approach. They don't need to know how everything works they just need to know how to put it together.
Everyone comes under the impression that the world has rules that must be followed, but honestly, it seems the are a lot of people in society who just.. don't care. Not out of malice, but pure apathy. Almost reads like exhaustion.
And yes, I'm trying desperately to get a new job, it's just really hard.
@@Rin-qj7zt wow. You just described the reality. I have leased a gas station once and few months into the business my A/C started to act up. I called the pros and sure enough he found a cluster of live wire pointing up without caps. He could have easily touched them and hurt himself. The building was almost 2 years old and just disgusting to see violations passed by the inspector. I wish you luck in your future job
One of the dangers of connecting a run of receptacles in series. One gets wired backwards and now everything downstream is backwards.
@@hassanbazzi3545 Before blasting the inspector, is it possible that the previous owner left you this mess?
Good explanation! I think you covered two of the three big topics: outlets, light fixtures, but also switches. If your light fixture is wired correctly, but your switch is wired incorrectly, I think you end up with the same problem. In particular, many people will do fixture work by flipping the switch off because they don't want to deal with the breaker, but if the switch is wired backward, you can still have hot waiting for a path to ground all the way at your work.
I came here to say this. Having a lightbulb with its threads exposed is a good example of something an everyday homeowner (or their kid) might do and not consider it in any way dangerous. But a DIYer trying to change a light fixture with just the switch turned off and not the breaker? That's a nice, educational shock for DIY electrical work. It doesn't matter if you know what you are doing, get a voltage tester or a mulltimeter to check for voltage before you touch ANYTHING.
If I don't want to play the breaker guessing game then I will tape the light switch in the off position. That way all of the people I tell not to touch the switch will have a second warning before I come down the ladder and dole out some verbal education.
@@docferringer
If I don’t want to play the breaker guessing game?
That’s equal to…
“If you’re willing to run the risk of a shock…”
It's difficult to wire the switch backwards because the black hot wire is the only one attached to the switch and the neutral white wire bypasses it.
We need to go back to wireless lamps and tech like it was before 1800 during the time of the giants
Knob and tube was better
THANK YOU SO MUCH!!! I struggled to find an explanation as thorough and easy to grasp as this one. I always was taught, heard, and knew it was bad if you reversed polarity, but outside of frying your plugged in device, I never really knew WHY it was bad. This demonstration with the bulbs, the way you showed how you could shock yourself, and the way you explained it, finally has given me the WHY it’s so bad!
I’m definitely saving this for future reference.
My daughter recently bought a house, which was inspected and the inspector found reverse polarity on one of the receptacles, which had a lamp plugged into it. She did not understand why this was unsafe or why it had to be changed. And I explained it much the way you are. Thank you very much.
You bet, thanks for the feedback 👍
Exactly. I've seen older metal lamps where a reverse polarity can electrify the entire lamp.
Years ago I tested the receptacles in the kitchen of a friend's office building. Sure enough one "neutral" was hot. The electrician got there is record time. Thanks. Glad I subscribe.
Thanks for sharing
SIMPLY THE BEST EXPLANATION ON THE INTERNET REGARDING POLARITY AND UNDERLYING SAFETY ISSUES. THANK YOU
I have seen this in many homes. The homeowners don't seem to want to understand because they have to pay me to correct it.
So, once I explain in great detail, they finally get it. I have seen more lamps that homeowners have rewired on their own, with reversed polarity than the light fixtures.
Great lesson for homeowners, you did a good job!
Quite frankly if you're touching the lamp base and get shocked then you deserved to get shocked. Unless you're trying to change a busted bulb. I've heard a tennis ball works for that. But if the bulb is intact there should be enough insulator to grasp.
I'm just a homeowner, without a great deal of experience doing home electrical wiring. For example, I knew that reverse polarity in a outlet was bad for the devices, but I didn't know why. And I had no clue about reverse polarity in light sockets.
Which makes this a timely video for me, because I have a light socket that is old and I need to replace.
Best of luck on the light fixture swap 👍
The device does not care. It does not know which side is hot and which not. All it sees is the difference.
I am working in a house that was built in 1947. All wires look black. This video prevented me from possibly wiring a new fixture incorrectly tomorrow. So easy to check with just non-contact voltge tester.
if you look closely, one of those wires will have a white or silver stripe on the side, although it may be worn away by now. BTW, if it looks like cloth covered romex and has a light silver glaze on the outside, it's impregnated with arsenic (poison) to keep mice from chewing on it. IOW, wash up after working with it.
@@rupe53 Thank you for the arsenic warning. It is "cloth" covered wiring in conduit on the main floor. Unfortunately, it is in BX behind plaster and it is not feasable to replace.
@@rogerhodges7656 ... my home was from 1910 so already have experience with wiring behind plaster. It wasn't fun, but that was 40 years ago.
I recently received my Journeyman license and I can say that this is a great explanation on why the polarity is importantant in the wiring. Thanks for the video.
Appreciate the feedback Ramon 👍. Best of luck on your career!
@@EverydayHomeRepairs any recommendation for testing reverse polarity in light fixtures where there isn't an easily accessible ground? Taking a light fixture down to check wires seems tedious when checking every fixture
@@lumby1412 You can get a polarity plug in tester, like the 3 plug type, and get a test kit from home depot that has alligator test leads, or lightbulb plug on it where you can put them on the "assumed" hot and neutral, and see if it lights up right on the tester.
I moved into a home a few years ago that was built in the late 1960s. I didn't realize that several outlets had reversed polarity until I was swapping in some smart plugs. Then, I took my tester around and found the others.
The electrical code probably didn't specify back then.
@@mharris5047 they are all grounded plugs with the wider neutral at least. It is definitely odd. It was built in 68-69.
@@CarnivoreRonin Same experience here - oddly, nearly exactly half of the outlets and the switches had the hot/neutral swap issue.
I purchased a rehabbed house over a year ago and I just found out that the receptacle for the garbage disposal was wired backwards between HOT & NEUTRAL and I found this out with my Fluke ST120 socket tester. For the longest time, the circuit breaker/GFCI would periodically trip and I do believe I just found out why this was happening because of reverse wiring of the garbage disposal receptacle...
THANK you so much for these videos.
Thank you. I have an old lamp with a two-pronged European that my mother has working with adapters. I am rewiring it for aesthetic reasons, and I can now wire it safely since it will be in my daughter's room. Great video and great explanation!
Well done explanation. This is why you never use a POTATO to unscrew a broken light bulb.
Most older homes have the neutral switched and a potato is mostly WATER.
Turn the breaker off and use a pair of insulated needle nose pliers to extract the base.
Good advice. I have used potatoes for unscrewing broken light bulbs. Including for a 150 watt high pressure sodium bulb in a yardlight that was busted from being hit with a football during a party. I was depending on the photocell not to kick on, super dangerous because of the high voltage ignitor, (2500 to 4000 volts) found in all high pressure sodium and smaller (150 watt and under) and many newer metal halide fixtures (pulse start metal halide)
DIYer. Bought an old fixer upper that needs a lot of updating. I want to make sure I get it correct. Thanks for your vids
You bet, best of luck on your projects.
If UA-cam videos could be rated five stars this would be a genuine 5 star video. Simple, to the point with well explained examples of how to tell if the wiring in your house is suspect. I totally expect your subscriptions to increase if you keep this up!
another note: older homes with knob-&-tube wiring, the neutral is switched, common practice at the time. when replacing a ceiling fixture, turning off the circuit is the best policy. fixtures is the same era with pull-chain & turn knobs, switched the screw shell or neutral.
I’ve lived in a variety of houses in different states. I’m always amazed what is not wired correctly. I would recommend a session on aluminum wire and Alcad sockets!
Hey John, thanks for the feedback and those would both make for good videos 👍
@@EverydayHomeRepairs Also would be good to explain what black/ white wires are in Romex. What should be hot, what is neutral.
@@JohnKenIRB233 Black is live (hot) and white is Neutral in the USA
If you have aluminum wiring in your house, have it replaced ASAP! Aluminum wiring just doesn't conduct well enough for use on mains voltage. This is one hell of a fire hazard!!!!!
@@markrobinson8539 Not always. General rule of thumb...yes. An example would be a light fixture like shown in the video but it is 'fed' at the fixture with just a 'switch leg' ran down to the switch. This would see the 'hot' fed down to the switch on one leg and back to the fixture on the other. Not typical in 'new' construction (with free access to open stud bays and the freedom to run what is 'easiest' and needed) but you'd be surprised how often it can be required in rewires or simply just adding a switch to a light that previously was on a pull chain. Code 'allows' for this...so never just assume that black=hot, white=neutral. It may be true more often than not....but it isn't a certainty.
YOU ARE SPOT ON FOR EXPLAINING THIS!!
IN THE 1950s ERA MY DAD WAS AN ELECTRICAL ENGINEER WORKING CIVIL SERVICE FOR THE NAVY!
IT WAS AT THIS TIME THAT THE 3 RD PRONG SAFETY CASE GROUND
SYSTEM CAME OUT AND HE WHOLEHEARTEDLY SUPPORTED THIS, AND CONVINCED THE US NAVY TO MAKE IT STANDARD SAFETY PRACTICE!
That light bulb example was excellent. I replaced a vanity light above a bathroom sink at an old cabin a few years back and it was not clear which wires were hot or neutral and I didn't have any testing equipment handy. I guess I had a 50/50 chance. Your test was perfect.
Thanks for the feedback 👍👍
This is a very good instructional video. I would like to add that if you remove the bulb, screw in a make light socket to 2 prong female adapter then insert a 2 prong male to a 3 prong female adapter then insert a Receptacle/GFCI tester only the “open ground” light condition will illuminate.
I purchased the Klein circuit breaker “finder” and I also bought the accessory kit to identify light sockets and switch circuit breakers.
If there are 2 fault conditions present such as open ground AND reverse polarity the 3 prong tester only shows the open ground condition. It will not toggle between both fault conditions. This is also true if you have both on open ground AND a reverse polarity on a receptacle. Only the open ground condition will be displayed. Once you “fix” the open ground then the reverse polarity fault condition will be displayed.
I like this video - I was just attempting to identify if my light sockets were wired backwards and the Klein receptacle tester will not allow me to do that.
I was recently installing new wall lanterns on my home when I came across one of the old fixtures wired in reverse. I guess the electrician was left handed because he turned the wire in the other direction. I saw that and wanted to be cautious so I checked with multimeter and found that the wire was still hot after the switch was turned off. Always good to check.
Excellent safety explanation. When I had to re-do the electrical in an old home that we bought, I found some of the light fixtures were not wired properly. Apparently, I was told this type of thing is not uncommon with light bulb wiring. Our home is now normal for the electrical safety.
The ceiling fixtures are most dangerous because you are usually on a chair or ladder changing a bulb. Getting zapped may not injure you, but falling off a chair could have very bad outcomes.
Old school metal recessed cans are grounded. Even brushing the springs or clips that hold the baffle in place have given me a zap before I finished screwing the bulb in. I'm guessing that was the easiest return when the threads were live neutral was switched off.
I honestly didnt know the reasons why you dont want reverse wiring but when im wiring in my house I alway make sure its wired correctly, But at least now I know the reasons behind why you want it to be wired correctly. Its really good information and ill always keep that in mind when im working with older houses that arent wired correctly.
4:20 The drawing really helped illustrate what the issue is. Thanks.
Thank you for this information. I was just recently replacing a burnt out lamp fixture & this information is going to help me from burning it out again. Again, thank you very much.
Good video. This is why it's so important to understand polarity if you repair a lamp cord.
💯
Many a Time when there was no outside receptacle and I couldn't get inside particularly with an older main panel, I would open up and attach a lead of a wire to the hot & another lead to the neutral bus- bar to run a skill saw. I never did make a jumper cord up in such a way I could plug a tester in and see if I had the hot and neutral reversed but I knew it would still work, although it's not 100% safe to do that without verifying that you have the hot and neutral hooked- up correctly.
This is the kind of stuff that should be taught at school level like so many other subjects that are critical for everyone when they reach an age that allows them to muck around. I hope your excellent video will get to be watched by as many people as it possibly can. Thanks for posting!
@Jannie Kirsten he was testing and showing what happens. Common sense if you are going to work on electrical you shut off the power in the panel.
I have recently watched lots of your videos, and they are informative. I am a beginner in DIY projects and want to learn more about how to do more DIY. Thank you.
You bet, thanks for the support 👍
I've seen the neutrals being switched in lighting circuits MANY times, especially in older homes. Never assume that power is interrupted with the switch in the off position; check it with a meter before doing any work.
OR JUST PULL THE FUSE OR BREAKER or do you trust the electrician? The wrongly-wired hot or live light fitting with some low energy bulbs can be enough to cause them to gently glow when switched 'off' and work fine when 'on' !
Hello Mr. Everyday Home Repairs, I am glad that UA-cam recommends your channel to me. Your explanation of the electricity is very simple and clear to me. This helps me a lot if I need to fix things around the house. Thank you.
I think the previous owner of this 1960-era house did much of the wiring himself when it was built. About half of all of the outlets (that were polarized, 2 or 3 prong) had the hot and neutral reversed, and half of the bulbs had the neutral line switched. There were also plenty of the 2 prong non-polarized outlets all over the house.
My dad found most of the outlets were wired in reverse in an older house that we moved into. Being an electrician, he fixed all of those. But I would not have guessed that unscrewing a light bulb would zap you. So now I know.
I have found the same problem in apartments I moved into, presumably wired by "professional" electricians.
The Edison screw (which is what you would consider a standard light socket) was developed quite a while ago. The polarized plugs and sockets used today were an attempt to make the Edison screw safer. The intent is for the large easily touched screw portion to be at neutral, while the hot portion is the little contact at the center of the bottom on the socket. (The easy to touch part = neutral, while the hard to touch spot = hot). Frankly, if the Edison screw were to be developed today, it would have been immediately rejected due to safety issues. But given how long ago it was developed, and how many of them have been installed over the years, it's a legacy device that's virtually impossible to get rid of.
@@johncochran8497 British use a bayonet mount that has two contacts on the bottom.
@@johncochran8497 you backwards, smaller screw for less current as neautral is a traveler conducter carries 50% of of the curent line , if add both togeatherif current line is 120 v ac and neautral line is 60 v ac = total 180v ac. From ground to neautral is 60 v ac if curent line is being used. The curent line and ground be 120 v ac. Only earth ground is 0 v ac
@@michaelspencer6523 You might want to try again there. Your comment was rather incoherent and wrong.
Perhaps you've confused about an Edison Screw vs an Edison Circuit. Even though both use the word "Edison", they are NOT related except in that they're both associated with electricity.
Electricity is the only thing that scares me doing little projects around the house, i don't know enough about its principles plain and simple. So videos like these help me a lot. Next up for me incidentally, is to put an additional outlet behind my alarm box so its power cord isn't exposed and dangling a couple of feet from the original outlet. Not sure if its a good idea or not, need to watch more of your videos for sure. At any rate thank's for taking the time to make and share your videos, i find them super helpful.
Very well done. This shows very clearly why polarity matters on grounded AC circuits. It's all in where the switch lies in the circuit. Very similar concept to why we always disconnect the negative terminal on a vehicle battery - there is less room for unintentional shorts. Again, very well done.
Great video. I would also recommend that people who move into a new rental or house check all plugs with your simple 3 light tester. easy to do and doesn't take long. Check lights before changing a bulb. On an old house I have run across a random plug or light that was mis-wired before I moved in. Always check ceiling fans and lights before replacing bulbs or doing maintenance on or replacing the motor. I have found these are mis-wired about 15% of the time.
This was super interesting and valuable to watch around unsafe vs safe connections: more videos comparing safe and unsafe situations around the home would be awesome!
Thanks for the feedback Ryan 👍
Well done with well thought out demonstration display. Thanks for the time you put in this video.
Happy to help and thanks for the feedback!
Great mix of theory and application in these videos. As someone new to this kind of work, it's great not just to learn what to do, but why it works. Thanks!
Something very important to note about basic plug-in outlet testers: if the outlet is not grounded, they cannot detect reverse polarity. I learned this when my parents bought an old house and asked me to look over the wiring since I’m handy with that sort of thing, and many of the outlets appeared to be ungrounded but otherwise okay to the outlet tester, but when I used a three-prong cord plugged into a known good outlet as a ground reference, over half the outlets in the house were not only ungrounded, but the polarity was reversed as well.
It's amazing what you find in older houses. I have no problem with DIY work, I do it all the time myself, but do your homework and take the time to make sure it's right if you're going to. As my father used to say "if it's worth doing at all, it's worth doing right". I am in an older house, not that old but old enough for the kind of house it is and every 10 minute project turns in to so much more because someone did something wrong to begin with. I'm also a perfectionest so even if it's a minor thing, if I let it go it will annoy me until I go back and fix it.
This is my dilemma in an older house that has no ground I have to figure out how to test for reversed polarity
Super helpful. I knew reversing hot & neutral was bad, but never had an explanation for why. It was particularly helpful to see the explanation about a device with a resistor. We had a ceiling fan with a remote burn out, where the control unit just melted. I couldn't understand why, and I think that's probably it. I'm checking that right now.
Best timed video. Exactly what I have been wondering since the weekend when I changed out a 3 way switch. I did not know which was hot and which was not. Thankyou!
I don't care since I shut off the incoming mains when changing light bulb but I do appreciate your advice on this matter.
Excellent explanation of reverse polarity….thanks for sharing the knowledge to others…safety first!
Outstanding, I’ve had a number of cases like that and had to do the repairs that home owners just didn’t realize the hazards they could have exposed them selves to. Great job, keep up the good work
i have experience in electric work but your advice is very helpful
Bro no more then 3 weeks ago I got zapped in the garage now I know what I need to do. This video is awesome and full of information. Thank you.
My favorite video program ....excellent...like to see more plumbing and electrical issues! Keep up the good work....thumbs up!
Just bought a tester to check my entire house. Thank you for the well made video.
You bet!
As always you taught me something today. I have a great respect for electricity and slightly frightened by it. However, you have taught me so many things by your videos, I would rather hang a ceiling fan than put in a new P trap. At least electricity is logical. Thank you🙂
Lol Why is a P trap not logical to you? The water it keeps in it keeps the sewer gases from your septic or sewer system from coming up through your drains. They can be toxic if you smell them over time… Google the issues with drug addicts fermenting their poop and huffing it. Gross, but it shows you why you really wanna block those gases from coming in the house.
Plus, it can catch things like rings if you drop them down the drains.
The problem with reversed wiring also applies to re-wiring of table and floor lamps, something an amateur is more likely to attempt - and get confused about.
I likely did that with my mother's table lamps when I was a kid.
Absolutely. If you change a damaged cord on a lamp, throw away the old unpolarized plug and use a new polarized one and make sure the wide prong is wired to the socket and not the spring in the center of the socket.
Just a few days ago, I just electrocuted when I placing Lamp for testing.. The hot is the outside of the E27 Cap
So I got mad and went to check the person that install the cable..
😒 But then I realize that I'm the one that install the cable..
@@XanderProduction It could be miswired where the outside wire comes into the fuse or breaker box. If that is the problem, short of having the electric utility come out and pull the meter so you can fix it you are stuck with it. Don't automatically assume you made the mistake. Check it but if it looks correct to you start investigating at the breaker and then where the outside service connects to the main breaker. In Michigan code requiring that the line and neutral be connected "properly" didn't hit the state electrical code until the 2000's.
@@mharris5047 ._.)/ You're correct about the regulation.. But I live in Indonesia..
It's actually me who make the mistake, bcoz I'm the one who check the Live-Neutral but misplaced the connector..
Reversing polarity is more dangerous on a plug than a light fixture unless you have a plug wired after the light fixture but it should always be avoided just the same. This was a good and valuable video. I have a 2 year degree in Electrical technology and so far all your electrical videos have been spot on. I also had 40 years working for a regional water authority, 20 of them as an inspector, and know more about plumbing than many plumbers. I have caught so called professional plumbers screwing things up and doing shoddy work. The problem is especially acute when the licensed professional sends a journeyman without checking their work. I have literally had to show some of them how to accomplish an unusually difficult task.
I've been doing wiring for years but never knew about reverse polarity for lamp sockets. Makes sense. Great explanation. Thanks!
Interesting. I did not see that coming, but I experienced it with a lamp years ago. I was taking out a lit bulb from a lamp and received a mild shock as I was turning when it turned off. Now I know why.
There ya go 👍
You should never touch the screw. If the bulb has broke off so that you need to use pliers then use special protection. In case of a plug in lamp unplug.
Potatoes!
Actually I never said it was broken, nor was it actually lit. I mis-remembered it which is why I remembered it at all, as pointed out in the video, you should never be shocked by a correctly wired bulb.
Thanks so much for the clear description. You’re saving lives!
This is something I learned in my 9th grade Basic Electricity class in High School. A very important life lesson.
Yet it's amazing how many people think polarity doesn't matter. There was another UA-cam video that mentioned it and the comments were astounding.
Thank you so much for you in depth descriptions helping me with my electric works. ❤️
I understand that with a reverse polarity on a light bulb that one could still receive a shock from touching the bulbs threads even when the light is off. How would one test a light fixture for correct polarity besides screwing in an adapter and inserting a circuit tester? Great job explaining this occasional problem.
There’s nothing wrong with screwing in an adapter and using a tester. Alternatively you could (carefully) use the test leads of a multimeter. Or more safely, use that in conjunction with the screw-in adapter.
You can use a non-contact voltage tester.
I always appreciate your videos...very clear and practical.
Excellent Video (a lot of UA-cam video makers could learn from this guy. Gets right to it with great visuals and audio.
Great job showing how to test the outlet with a tester. But it’s also possible to use the same tester to test a light socket. You just need a few more pieces to connect as follows: Mount an outlet in a box and add two male cords. One cord is polarized two pin and connects to the outlet at hot and neutral. The other cord is three pin and ONLY connects to outlet ground. Then plug outlet tester into outlet. Plug a polarized light socket to outlet adapter into the light being tested. Connect this whole device up using the two pin cord to the light socket and the three pin cord to a known good grounded outlet. The outlet tester will report if the light socket is reverse polarity.
I’ve done this test at many houses and most older houses have reverse polarity lights. My own house built in 2004 has half the lights wired wrong. And that’s by a professional electrician and passed inspection.
or in a house that is new enough to have a grounding conductor, plug a grounded extension cord into a known good receptacle, and use a continuity tester to check between the ground pin of the extension cord and the screw shell of lampholders. or hold a non contact voltage tester to the screw shell.
Great explanation on how to use the Klein tester and also the probe.
Your example explaining what happens when wires are reversed with a light bulb s an eye-opener! Yikes!
Thank you. Much appreciated.
If someone theoretically completely scrambled up the wiring so that the ground and neutral wires were actually connected to 120VAC, and connected the hot to ground, the outlet tester and DMM testing would show everything is just fine.
This is where a non contact tester would be helpful to identify this odd situation, as that would easily pick it up.
If you're up on a ladder and didn't have any known ground reference, the NCV is a good confirmation to have along with the other tools.
This condition actually happens more frequently than you might think. In an old house that was originally wired with 2 wire ungrounded circuits and two prong outlets, sometimes 3 prong outlets are installed without providing a ground wire. In order to fraudulently pass a home inspection and make a 3 light tester indicate correct wiring, a jumper wire is inserted between the neutral and ground screws, aka bootleg ground, or false ground. If there is also reverse polarity, you have a reverse polarity bootleg ground (hot connected to neutral, neutral and ground pins sitting at 120 volts to ground potential) tester will indicate correct wiring, and most if not all appliances will appear to work properly, except a device with metal housing and a three prong plug will have it's case live. And with the possible exception of sensitive electronics, most devices will work without problems, if the polarity is reversed, just not in the safest manner.
Great demo and visual aids and theory behind the topic. Thank you!!! Good advice on safety as well!!!
Excellent video and easy to understand explanation of a common unsafe electrical situation! Thank you!!
Owner of a 1913 house here with a lot of original wiring. All the switches/fixtures are wired with a switched neutral. Supposedly at the time they thought it would extend the life of the switch. I got a small but painful shock changing a light recently. Now I am very carful or I turn off the breaker.
I had this problem working maintenance in a restaurant with a warming cabinet. The wires were actually swapped in the breaker panel. Employees were complaining that they felt a 'tingle' when they touched the cabinet. The entire cabinet was energized all the time.
I work as an electrician as well. One of customers gave us an antique light to install but the wires had no indication which was ground, neutral, or hot so ended up pulling my meter out to figure the three wires and hook it up correctly using the ohm setting.
This condition can be found more often when repairing a table lamp. The lamp cord used to wire table lamps and some multi bulb ceiling fixtures has a identified conductor unknown to most DIYers. A close inspection of the lamp cord would reveal a rib molded into the entire length of the cord over only one conductor. This is the neutral and would go to the shell of the bulb socket. Lamp socket/switch combinations do go bad occasionally and need to be replaced. Look for the identifying rib on the lamp cord and make sure it is attached to the shell of the socket. Sometimes the cord manufacturer will stamp the information about the wire in the insulation instead of the rib. This will also favor on conductor over the other. Again, this is the identified neutral conductor and should attach to the shell of the bulb socket. Another great video.
I work on a lot of old houses in the Denver area and I found another issue where they ran the hot wire directly off the breaker box to the light fixture,then to the switch, and then from the switch to common. So you can turn the switch off and there's still power at the fixture.
Yes, I have ran into that type of circuit as well. Not a fan 👎
Same here, ran across that a few times as I was helping my step dad rewire his 1973 double wide, which had numerous problems with the aluminum wiring including a metal junction box concealed in the wall (highly illegal and dangerous, for those aware all splices must be accessible meaning it cannot require removal of the building materials to access) that had overheated to the point of charring the stud. I am not a big fan of this fortunately the code required a neutral be present in a switch box since 2011, making this wiring configuration virtually extinct, the only legal today, is to run 14/3 NM from the light to the switch box, which is pretty much pointless 99% of the time.
I remember back in the early sixties, wall sockets were usually ungrounded although polarized, however, the plugs were neither grounded nor polarized (two prongs, both the same width).
Enjoy your videos. Your explanations are perfect for me. Thanks
I just moved into a new house and found several outlets with reverse polarity, open ground, or no power at all. Checking the circuit breakers, the legends were all obscure and had to trace the entire house to correct. I am a licensed electrician and that was the first thing I checked even though the inspector failed to identify these issues.
I got a tingle one year replacing a burned out C9 Christmas lamp on my outdoor Christmas tree. I was using a pre-polorized string set.
When you're outdoors it is easy to inadvertently come into contact with the ground. When you do then you're electrically grounded. We use a ground reference for safety but the fact that we do creates a local hazard. Basically if you have to mess with electricity outdoors be careful and try to wear insulative footwear. You do not want to be in the return path for current.
Another thing that you need to look out for is when the switch is beyond the fixture. Ex: Power comes into a ceiling light fixture. The hot lead (black) should be connected to the black lead going to the switch and not to the black lead going to the ceiling lamp. The neutral (white) coming back from the switch is now the hot and should be marked (usually a wrap of black electrical tape) and attached to the gold colored terminal or black lead of the fixture. The neutral (white) of the power supply cable is then connected to the silver colored terminal or the white lead from the fixture. Many DIYers get this messed up.
Thanks for this. Great description of the issue, the problem it causes, and how to troubleshoot it.
Man thank you so much for your video. In 10 minutes I learned more than I had learned and understand about wiring issues 😅. I’m definitely subscribing!! Thanks again
This is why you should hit the breaker before working on a light, if somewhere along the way the polarity was reversed, the switch being off will not help you. I always check and recheck with a dummy stick (hot and neutral) before I go to work. 99.999% of the time it just scares you sometimes it hurts a little bit and it could kill you.
Sometimes a neutral or two from a different circuit might be in a box. It won't set off a non-contact voltage detector, but could give you a serious belt if you separate those "return" conductors.
@@thomaspierce9458 I see that happening, but it would be a perfect storm. also a neutral from a different circuit should be accompanied by a hot from a different circuit, which would be detectable. Once when I was really stupid, I got zapped three times, before I decided I would just hit the main, and avoid a fourth zap.
Always love watching your videos!
Thx!
What a fantastic channel. Not to be missed! Thank you!
Clear explanation with good demonstration. Thanks Sir👍🏻
You bet!
Good warning video that should be followed by home installers.
Greetings from UK where we do everything different (mostly).
For a long time, lamps here have used a bayonet cap, not screw cap, but they can suffer from indentation of the contacts. I am, (like more and more people here) now using ES27 and ES14 lamps as in the USA as they are better.
I always double check the cables to ensure that the live (hot) line does go to the centre contact as in your video.
For all practical purposes, outlets have to be tested with a proper device similar to the one that you demonstrated, as the contacts have shutters to prevent anything being pushed in. For my most recent home installation, I have upgraded to a Martindale tester which also measures ground loop impedance.
I have found some incorrect wiring in our new home here and have since corrected it, but the worst that I have ever seen was in a house to where we moved in the 1980s. The metal frame of the kitchen 3-spotlight unit was connected directly to the (always on) hot supply instead of ground. I have long suspected that this may have been the cause of the previous owner's death, rather than "heart attack".
Almost 2/3rds of my house is wired like this. Built that way. Not to mention a million other crappy shortcuts taken throughout.
But it amazes me at the box everything appears correct. 🤷♂️ I can only assume there is a junction somewhere that reverses (somehow) and continues on. I only found this out when I started the process of updating fixtures, switches, and outlets
That is a real possibility, I've seen that. If this is your problem, hopefully they didn't bury the jct box in a wall somewhere!
Thank you, really good explanation of the hazard with reverse polarity
Simple rule of thumb... DON'T TOUCH the electrical metal doesn't matter if it turn on or not. Just like even if a gun is unload, you don't point it to anyone's head and pull. Always consider it is live or loaded.
Even with the light out I'm a bit concern touching the metal contacts. Never know if there is a cap in there that still storing charge. If i care i would short it out and than touch. But just don't touch is simplest.
Great content thank you as a DIYer all this extra knowledge helps out a lot and thank you for all the great lessons 👍
I had a reverse light bulb socket, I actually found it when I installed an led. I have almost switched all my bulbs to LED, but the fixture in question I noticed a very soft glow when the switch was off, it was such a low amount of output that almost all other light sources had to be off, so I put that led in another fixture and did not have the same symptom. I actually discovered it was backwards at the switch, which meant hot was always hot, but still hopefully that’s useful information to someone
That glow is caused by capacitance between the wires. You can get it even without a reverse switch but that does increase chance of getting it. Better bulbs have methods to prevent that. U just shows how sensitive the bulbs are.
A common method of wiring a switch is to draw one cable from a junction box into the switch and use the neutral as the return. The two wires close together create a capacitor that passes some AC.
Some older devices - like radios from before 1960 - can be very dangerous with a reversed outlet since the neutral line of the plug was often connected to the chassis. Plug it in backwards (this was before polarized plugs) or into a reversed outlet and the chassis is hot & if you touch a metal part of the case you’ll get a 120V shock.
Only in usa.
The rest of the world didn't have that issue .
But then usa was and is a 5th world nation
@@janee7995 Those old electronic devices with tube amplifiers often had the chassis connected to one side of the line, as you correctly said - but not only in the USA. They would be made this way and sold in Canada as well. (I had a few shocks putting the tone-arm on a record.) If tube filaments were in series, this would also happen in other countries with different supply voltages - and no neutral for a return as on the continent of North America.
Those have unpolarized plugs unless modified. I consider those unsafe. period. Note with an unpolarized plug there in principle is no wrong way. It was seen acceptable that the chassis was hot.
In Europe they cannot be plugged into grounded sockets as that would be too dangerous if you had a grounded computer next to and there is no legal way besides an isolation transformer to use them.
@@thomaspierce9458 Those were made in most countries. The difference is that in Europe the plug does not fit into grounded sockets so you need to do something really stupid to use them.
believe it or not, kitchen counter appliances were also non polarized back then and everyone had that spiffy looking chrome trim along the counter edge, which could easily ground against the side of the electric stove or the sink. I can't tell you how many times I got a morning wakeup call if I leaned against the counter with a small gap in my bathrobe while making toast! (not what you think because I was shorter then)
This was an excellent explanation of reversed wiring and of the consequences. I also really appreciate the education here.
Thank you. For an Alternative Ed High School class, I worked up a board to show what happens in parallel and series circuits. It was interesting to see what happens with varying the bulb wattage in both types of circuits. The same kind of board could be used to demonstrate three way and other switch combinations as well as the impact of a dimmer switch. Explaining what happens in that type of circuit would be informative too. Thank you for your clear narrative.
I am learning so much-you have an excellent way of explaining things! Glad I found your site. 😁👍
An additional comment --- when checking voltages with a DMM, always reference to a known ground. Some may assume that they can check voltage using the Neutral as the reference but this could lead to incorrect readings with AC voltages if another fixture in the circuit is incorrectly wired. Also check BOTH Hot and Neutral during the same test.
Not an issue... As he was only checking if there was ANY considerable voltage... Might read wrong but that is not a problem in this measurement.
If it's an old house there is no ground usually
Great example and explanation! Thank you!
Great explanation and content! Always learn from you videos!
Really nice visual explanation of why reversing hot & neutral wiring can be dangerous
I got some outdoor plugs in new place I bought that worked with the old bulbs put don't like LEDS for some reason. The LED's have power but flicker like a strobe light. I'm going to check for reverse polarity.
Great information, well explained. Can you do a video on deleting a switched outlet, changing it to constant power, then utilize the switch to operate a ceiling fan/light combo? Thanks