Why Neutrals & Grounds are Connected in a Main Panel
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- Опубліковано 17 гру 2020
- 2020 NEC Handbook: amzn.to/3p1Szs7
Why Neutrals & Grounds are Separated in a Sub Panel: • Why Neutrals and Groun...
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Here I explain the reasons behind why the neutrals and grounds are tied together in your main panel or first disconnect means to the best of my ability. We will discuss the difference between bonding and grounding and why an electrical system is grounded in the first place. We will also look in the 2020 NEC code book and learn what an Effective Ground-Fault Current Path is.
Some of the questions this video should address:
Why do the ground and neutral wires go to the same place?
What is the purpose of grounding?
Where does the neutral wire com from?
Is the neutral connected to the main utility line neutral?
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Blessings from Minnesota,
Ben
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Several times you said that grounding(by a rod into the ground) is only for lightning protection, this is incorrect. However, you are providing no bad information. Grounding is very important. I design grounding & bonding systems for electrification of rail networks, power substations, transmission substation etc. etc. etc. I hope this quick information will make you to think.
Almost everything you say in this video is wrong.
@@UA-cam_Stole_My_Handle_Too Thanks!
Earth or Ground wire is named this way because its physically grounded to provide low resistance path for any faulty or surge current, including thunder spiking current, static discharge, current fluctuation in loading changes, current spike in switching, circuit crosstalk shielding, etc. It got nothing to do with "bonding" to Neutral as fault current return path. That's purely US system jargon that distorted and confuse everyone.
Grounding is very critical in all electrical and electronic designs, from high voltage power distribution to semiconductor IC.
@@UA-cam_Stole_My_Handle_Too If you're going to fondle your balls for all to see, at least provide substance of value for the rest of us to learn from. Nobody, not even mom, likes a self important jerk.
Grounding/Earthing is one of the most confused topic also among professionals and I being an electrical engineer have not found such an easy and clear explanation of it in last 10years of my research about this topic. Thanks for this good work Ben and please spread the rare knowledge which you possess. Thanks a lot.
If I can ask you a particular question: would you think that ground, I mean the grounding rod and earth itself, is *REALLY* a return path?
I don't think so, but I still get "earth return path" in every book and every teacher tell this.
@@tanner1985 The wood poles the transformers are on insulate the center point, the neutral point, of the two coils within it from any rod you drive in to the earth.
Like the video said, earth rods are for lightning. They work for lightning because the planet is the source of lightning when you consider the electrostatic gradient between the sky and surface.
If, in theory the neutral point of the transformer was also connected to the earth with a rod, then there would be a path for return between two earth rods. But this is ineffective as there is great resistance over great distance in soil power transmission. So in that case power would not really have a return path anyway, and build up in all your devices, arc all over the place.
@@tanner1985 The earth itself is a return path for the current back to the distribution transformer but it is not a very good one. Using the neutral line is far better..
In the UK there are several methods of returning the current in use, which have evolved over many years and dependent upon constraints in the locality of where the building is situated. Where the earthing rod method is used the regulations specify an upper limit on the impedance of it to be sure a high enough current can flow to trigger the circuit breaker. Obviously the earth/the ground under our feet, its composition: soil, clay, rock, moisture content is massively variable.
Sometimes you have to using a grounding rod placed into the earth as the method to provide the return path. Just do it the best way you can, and don't take shortcuts on it and measure the impedance of it after construction to ensure it really is going to be effective.
@@89Ayten Some of your statements are not entirely correct.
In the UK we have several different earthing/grounding strategies in use.
One of which is referred to as protective multiple earth (PME) where the neutral line provided the return path for a fault current which is flowing down the separate yellow/green earth wire (the earth wire is connected to the neutral wire at the cable entrance to the property).
Another method used, is a grounding/earthing rod is placed into the ground at the property. And the distribution transformer also has an earthing rod placed into the ground too. The return path of the current is then literally through the ground from one rod to the other. And it is effective. But our electrical regulations also specify a maximum impedance in ohms for the earthing rod at the property end to ensure a high enough current flows to trigger the circuit breaker located in the distribution board of the property.
So it is effective but only use the grounding rod approach where there is no other alternative. We are able to contact the power company and they will tell us which we should be using.
I think a lot of the confusion and poor education on this topic comes from electricians and trainers of electricians that really do not understand electricity and are unable to perform basic circuit analysis because they are not taught this skill or spend enough time on the topic in their electricians courses.
Now, for degree qualified electrical and electronic engineers it is quite different. They spend a full 3 years studying a huge array of topics and maths, including Kirchoff's Laws, Thevenin equivalent circuits, complex number theory to represent sinusoidal waveforms and phase shifts between voltage and current.
The topic is not difficult, it really isn't, it's just that the trainer's of electricians don't really understand it themselves.
Ben in addition to being technically excellent, you are also a very talented teacher. Your pacing, selection of instructional points, and language skills are in a different league! Also, the moment where you invite people to correct you was very humble and touching. Good job!
Consistent with being a good teacher, he was open minded to other ideas and suggestions. Here is one.
Benjamin Sahlstrom
I have a response you asked for, .. for 13:40 and 18:22 . .. but first, thanks for the video. For me, you were number two great video on this subject, so I already knew some of the key answers but had some doubts until watched your video.
The motivating question is that if ground and neutral are connected does that mean they are the "same" thing? The answer (which will also include an answer about static discharge 13:40 etc) is that neutral serves as the primary path flow for electrons in circuits when they are working correctly. Ground serves as the back up branch. Correct behavior implies neutral is being used. All is working according to design. In contrast, any flaw (fault) will hopefully be caught by a ground path back. The fault situation is not ideal and can be unpredictable.
Among the flawed conditions are tiny amounts of stray charge getting in places like the metal outside of appliances. Here that imperfect situation is caught just as if there were a full fault. Stray discharge is just the weak sibling of the full hot wire fault condition. The ground path back is taken in either case. The main difference is that by definition static accumulation includes very small currents so the path back does not lead to tripping the circuit breaker, but, nevertheless, any such imperfect leakage current is brought back to the neutral and away from the appliance where otherwise there would be an accumulation (like van de Graaff generator) that could be more harmful if large and could hurt people or electronics, etc.
So the short answer is that avoiding a charge accumulation is nothing but grounding addressing a weak version of a fault. No circuits are tripped, but charge does get to places that are not as intended by design under perfect functioning of the appliance, and thankfully a ground path will be there at that moment to lessen the potential damages just as it would be for a full fault. [discharge = weak fault.. ground carries current back, avoiding a potential van de Graaff generator greater fault threat]
[partial disclaimer] This and the other video I mentioned ( ua-cam.com/video/P-W42tk-fWc/v-deo.html ) were very useful to clarifying some things for me. I may still not be correct of course. Also, Benjamin might have known the answer or I misinterpreted that whole scene. ... etc etc. thank goodness for youtube videos :)
Question 1. Is there a dedicated, unique and special Grounding for Sensitive Electronic Equipment?
2 Question.
In the event of a lightning strike near my property is it recommended to unplug my electronic devices?
3 Question. Why is there always a little (0.3 Amps) current flowing from the neutral bus bar (on the main panel) to the ground rod ?
Does it mean that some of that current could leak out
through the equipment grounding conductor form the main panel to the sup panel energizing the equipments conected to the EGC?
I would appreciate it so much if you help me answering those 3 questions.
This video is the best explanation of ground/neutral set up for someone who’s not an electrician. I can now wire up my sub panel to my shop with confidence and feel safe doing so. Thanks Ben
Thanks for the explanation
Some folks just don't understand how to teach a subject such as electricity flow. You are a very good teacher & explain the things that others leave out, because they don't have much intuition when it comes to the thought process of the student. Thank you for making your videos the way you do!
As an industrial designer who worked at two major lighting manufacturers (and Klein Tools) I have run into countless engineering coworkers who refused to provide a sketch in creative meetings or after some private time in their own space. If it ain’t done on a computer I guess it is not real. Kudos, Ben, for proving that one should not let perfection (in visual illustrations) get in the way of progress. Sure your drawings are a bit rough but they are more than adequate along with your exceptional dialog to explain what has been for too many an elusive topic. May the 2022 NEC deities smile down upon you and your work.
Have been struggling to understand this for about a year, reading books, watching videos, FINALLY! You are a great teacher. Thank you.
Mike Holt does a great series on Grounding, and is one of the primary people responsible for driving home the message (often miss-understood by even electricians) that Electricity doesn't want to go back to the ground, it wants to go back to the source. There's a lot of miss-information out their that connecting something to the ground "makes it safe", which is 100% wrong. What makes it safe is turning it off, and of course that happens via the breaker tripping. That can only happen if you have an extremely good connection to the source, i.e. the neutral wire. Ben does a great job of putting the basics into a short, watchable video. Mike Holts video is an hour long, but well worth viewing if you're interested in a lot more detail ua-cam.com/video/mpgAVE4UwFw/v-deo.html
@@stevesether Good comment... Why don't some electricians understand this, because I would have thought they had to study this subject and pass tests to become licensed?? Or, maybe the reasoning for this isn't necessary to become an electrician??
@@jacksak Memorizing enough to pass the NEC and understanding are 2 different things.
@@miketritsch6166 Good point...
@@jacksak I'm not sure... I think a lot of being an Electrician is more practical, and not all theoretical knowledge. i.e. knowing the why you do something isn't required to do it, you just need to know the rule.
Now, I'd argue the why (or how it works if you prefer) is also incredibly important, and lets you better understand the practice in a greater context rather than a set of rules to be followed. But I imagine some people sort of gloss over that part because it's not strictly required.
Great explanation! As Einstein said, "If you can't explain it simply, you don't understand it well enough."
Amen to that, its simple logic, the only way to explain how it works is to KNOW HOW IT WORKS ...
But not everyone is gifted to teach to where most will understand
Quantum mechanics: if you think you understood it the first take, you didn’t understand it.
Einstein never said that. Feynman said something similar, as did others. In fact, Einstein said that if he could explain something to an average person, it wouldn't be worth a Nobel Prize.
I really appreciate this very clear explanation on bonding/grounding. Been working with electric for 40+years and didn’t have this clear of an understanding until your video. Thank you very much!
WOW - I thought 20 minutes would be too long, but you did such a fantastic job of explaining this!
At last someone knows how to perfectly explain this very confusing topic. Bro you are awesome, you are an expert. I am extremelly surprised u way u easily explianed this bro.
Ben has a good understanding of residential wiring. Not always the technical terms are used but close enough. Good job, Ben. Retired Utility Co. protection and control engineer.
Nice lesson Benjamin! About those "stray" or "leakage" currents. Those currents are caused by inductive or capacitive coupling. Those are both "non-galvanic" meaning there is no metallic connection. They can be confusing because they don't need frayed or broken wires to cause official ground faults. A capacitor is two plates separated by an insulator. Alternating current passes thru capacitors depending on the capacitor plate area, frequency of the alternating current, and distance between the plates. If you were to take a capacitor and connect it between a Hot and, say, an unbonded/ungrounded enclosure the enclosure would become live. It would not be at the same level as a metallic wire contacting the enclosure but could easily still be fatal or cause an accident due to uncontrolled body motion.
Sources for leakage current are any products that have lots of conductive metal near other metal that is ultimately fastened to touchable metal or enclosures. The most common found around homes are motors. In a motor you have thousands of wire wraps close laid on metal in the stator. So many wires add up to many square inches or even square feet of pseudo capacitor plate between the windings and ultimately the metal structure. Hence current is conducted via that capacitance to the chassis. Having that chassis/framework/enclosure grounded gives that current a return path and sets that metal to "ground potential".
Most people struggle to understand inductive and capacitive coupling in electrical systems because we teach the intuition that electrical current is the flow of electrons through a wire (which isn't really what's going on). The reality is that power is carried through the field and so electrical systems can cause stray currents through numerous field effects. I've heard of electrical issues in industrial equipment getting cleared up when the engineers are told to move a ground screw on the chassis by 12". Field effects are very hard to intuit and takes a fair bit of experience and knowledge.
Perfect
Until the white, black, red and green wires realize they are all copper on the inside, only then will they all truly connect.
Electrical DEI in action ... next we will have to learn all their pronouns :(
Doing a total remodel of a 40 year old house, total upgrade and increasing from 200A to 320A, splitting the service at the meter equally to the house and the garage with to external switches. After seeking understanding and advice from industrial electrician associates of mine at work, and still being quite confused, your videos have helped me tremendously in understanding the principals for why this system is wired, grounded and bonded the way that is correct. Thanks a million for your service to the greater DIY public who seek understanding in order to perform home projects properly and also safely and to code. Well done!!
I love this, you really bring things together! When I was young (70s) I often got shocked through my body when grabbing the door handle of the old fridge in my unfinished basement especially with no shoes. My family never believed me because I couldn't repeat it when I tried. Now I've become the electricity expert in the family (and the least sensitive to shock)
This is a brilliant explanation! I studied electricity/magnetism at the college level pursuing my BA in Math. I have done wiring for over fifty years, but never completely understood the role of the neutral and ground systems even though I've carefully done it correctly. I always thought the neutral/ground was a redundant ground. Now that I know the neutral is a center tap of the secondary of a transformer, it makes perfect sense. Thank you so much!
Henrik Hansen, DDS
Former marine engineer, shipboard engineer, shop teacher, home tinkerer. This brought a lot of things home for me.
Too late now. It's scary imagining all your mistakes.
@@mikemondano3624 WTF are you talking about?
@@mikemondano3624 lmao
Ben is a true guru. I'm blown away by the detail and thoroughness of this video and all his electrical videos. Masterful.
This is the best explanation I've seen on any UA-cam video about the grounds and neutrals. I always learn something from your videos.
Natural has power n control to ground which connects to metal esp appliances so how come not hot . Shock you if natural n ground together. This is the only question I could see needs to be addressed yet you did not . Why ?
Neutral has electric current . Why don't we get shocked if grounded to metal n appliances. This is the only question needed. Why did you not explain why we dont get shocked ?
@@ronaldariaaria1781 impedance
@@ronaldariaaria1781 I have been shocked by neutrals MANY TIMES, so this is not necessarily true.
@@ronaldariaaria1781 the neutral carries the unbalanced load only. Usually lower voltage than the hot. Its then bleed to ground. Take the neutral off the panel connection you will get zapped.
I'm just a DIY'r, but always wondered about the differences between ground and earth and why the bus bars are connected in the panel. This cleared everything up. Great video!
one thing is also that grounding all equipments means they are all on the same potential, meaning if there is any current leaking that is not enough to trip the circuit if you touch two different devices or like a metal pipe and a motor or different machines you will not get shocked because there is no voltage difference between them.
One of the absolute best You Tube videos I have seen in a long time. Clear. Concise. Accurate. Thank you.
Great job, Ben. I once asked a friend who is a master electrician the question of why grounds and neutrals are connected in the breaker box. He talked for 5 minutes, but said nothing. Now I get it (kind of)! Thanks! Cheers!
i got the same response i got, all i was told its a type of shared earth but went no further
The haters (99%) can't
Understand this class. love this class!
Much love to you're knowledge.
I have been building/wiring for 50 years and yet there are a few details that I had yet to grasp. YO ! finally I got it ! Thanks Ben..... I,m building my own last house and feel good about it,s safety. Keep it up.!
Ben, I am 58 years old and I have always regretted not sticking in the electrical field when I used to do grunt work down in Arizona. I have always wondered about this neutral and hot question and you have answered it for me and I did go ahead and subscribe to your channel and like the video. Thank you so very much!
Used to be a Navy electrician and it was fun tracking down fault lights. Every panel we had had three fault lights that when we press the N/O button it would light the leg that had it. Then it was just turning off/on those connected breakers to see when the light wasn't illuminated. Great video. Thanks
Would your 240V circuits also have those ground fault lights? Most commercial vessels in Gulf of Mexico bond neutral to ground on 240V circuits.
Ships are ungrounded electrical systems. Wye/delta. The secondary is not grounded. 440 system. This design is used to eliminate interruptions in service. For example if a ship is navigating in hazardous water, you do not want to go off line for a simple fault. It takes two faults to cause an outage. And therefore it is important to correct any fault when an imbalance is detected.
This type of system is also used on land in production facilities such as ice cream factory, or production where an outage is costly.
I don't usually comment but this specific subject has been a complete blur for me for YEARS. The parallel path explanation solves it and my brain can finally stop melting. This had me stumped for you don't know how long and I'm an engineer, just not an electrical one ;) Thanks! Subscribed!
This is the clearest and most complete explanation of how grounding and bonding works I’ve ever seen. I learned a lot. Thanks so much!
Here's one thing to keep in mind too. Not all grounds go to a grounding rod. In older homes, sometimes they are grounded through the cold water pipe if you have copper lines in your home. If you go to where your water main is which is where your plumbing system comes into the home, you might find a bare wire in a grounding clamp. If you follow this wire, it might go to your power box. In our area, we are required to have 2 grounding rods as well as a wire going to the cold water pipe right before the main shutoff valve. Here's another thing for you. If you ever noticed on your equipment how one blade is wider than the other, that's because the item is being grounded through the wide blade. Things like your stereo with the metal casing and a lot of the newer plugin style power tools gave them. They call it a "polarized plug." It's because the ground wire and the neutral wires come together in the main service panel that they can get away with grounding things through the neutral blade. This is why you should never defeat that wide blade to fit. They are designed that way so they only fit in the plug one way. It's so you can't plug the plug in backwards causing the neutral/ground to be hot. It won't do anything and the devices will still operate. But you could get a shock because by plugging the plug in backwards, it bypasses the ground. Surge protectors work in that way to protect your equipment from excessive power spikes. When a surge protector detects a surge, it reacts to catch that surge and direct the excess current to the ground. Another point. The grounding system can also help reduce interference in radios which is the stray noise you sometimes hear in the form of a hum. Old component style record players often had a small wire that came out of it. Old stereo amplifiers that had a phono (phonograph) input also had a grounding post where you would connect that wire to to help ground it which usually stopped that power supply hum you would often get if you didn't use it. On the newer stereos that don't have this feature anymore can still except record players. All you have to do on these is open one of the screws that hold the metal cover on and wrap that grounding wire under the screw and tighten it down again. This will effectively give it the ground it needs to stop that annoying power supply hum.
Now i know. So much I learn from you sir. Thanks!
We had our electrical panel circa 1959 upgraded and as you mentioned the ground was only going to the water main in our basement. When they upgraded the panel they added two 6 or 8’ long grounding rods outside our house along with some very stout copper wire going to them. Interesting to watch!
Thanks for the knowledge! I used to have an extension cord that could accommodate a polarized plug in either direction, I never thought much of it but now I know!
@@scheppa2000 2 are not needed if 25 ohms or less..........fyi
@@GR-zh4ol vertasium: current doesnt FLOW in conductors VIDEO ** ! **
Thank you for acknowledging the existence of ship’s electrical service. As a former mariner (engineer/electrician), it makes me very happy.
I’m a math teacher and I’m very impressed with how well you explained this man… Nice work man!!
Bravo!! Mr 200 should be your name! It took me YEARS in the field, and 5 yrs at a JATC program before the ‘lightbulb’ lit and to grasp the concept! You could EASILY teach the grounding class better than 80% of the instructors! I think homeowners could even understand your explanation. I always tell them it’s not for them to understand, if you don’t want little Susie to get fried and your house to burn down don’t mess with it and call me. It usually scares them away from any dreams of being a DIY electrician! Thanks Ben, keep it up.
Thank you so much for your clear explainations, real world application and use of a diagram. You basically covered one semester of my electrical trade school class in .20 minutes. You are a natural at teaching, please continue making your videos.
What he said^^^^
I've always known what to do, but today I just learnt the "why" it is done that way
I seent em
Excellent presentation. I will ditto the previous comments. My grandson is preparing to become a lineman and I am going to recommend to him that he become familiar with your presentations. I’am an old dog electronic tech that never got deep into power systems and I am learning a great deal from your program. You should appreciate your talents, few people are able to convey information the way you do ! Keep up the good work ! 👍👍👍👍👍
Thanks Ben! Brilliant explanation! Often we Engineers get negligent to basics and start to overlook the veracity of electrical system.
Thanks, again! Very good refresher!
I have worked with a ton of guys in the field that know the rules and have no understanding why, glad to see your video!
Too much NEC not enough fundamentals. This is typical electrician going through the motions without understanding. This guy is an exception.
I understand the HOW. You help me to understand the WHY. Great video.
Time stamps:
* 00:15 The first disconnect means (FDM) in your main panel after your electrical meter is where your neutrals and grounds are bonded together - white wires and copper green wires tying into the same location.
* 1:03 Electricity --> transformer primary side to secondary side at 10k volts --> electrical system at 240v --> center tap to tranformer winding (where your neutral comes from) for 120v (which are grounded).
* 1:30 The neutral of the main utility line is physically connected to the neutral of your electrical system. This goes through the electric meter to the first disconnect means/main panel where neutrals/grounds are tied in at the same location
* 2:15 Utility neutral is physically connected to the neutral of your electrical system.
* 3:25 Metallic objects in the electric system are tied together via the grounding wire and bonded the neutral. A green screw specifically connects the neutral to the enclosure of the system.
* 5:00 Bonding is connecting all of the electrical parts of a system together. We are discussing it today with the equipment grounding conductors (EGC). The EGC ties metal components of a system that normally don't carry charge to the grounding conductor in case of a ground-fault.
* 6:32 The Effective Ground Fault Current Path (EGFCP) - a low impedance path that carries current from a ground-fault to the electrical supply source, allowing deployment of over current protective device/ground-fault detectors (from: 2020 NEC Handbook)
* 7:24 Multiple electrical appliances in your household are connected to the same EGFCP to ensure the protective breaker to trip in case of a ground-fault by bonding to the neutral.
* 8:55 If your system is grounded to the earth but does not have a feedback loop (EGFCP) the protective breaker *will not trip and your system is still unsafe.* Grounding is not what allows this safety check, bonding to the neutral (and source) is what allows this check and makes your system safe.
* 10:00 The neutral will draw more energy than the circuit breaker with a ground fault short which will allow the safety breaker to trip.
* 10:33 Electricity doesn't necessarily want to return to ground, it wants to return to its source.
* 11:10 The ground is connected to the source in case of lightning.
* 12:20 Ship engines are ungrounded systems. The generator doesn't have any portion of its winding connected to the ship frame.
* 13:34 Grounding also can get rid of excessive static electricity, but Ben's not sure why. If anyone knows, please comment.
* 15:14 We separate neutrals and grounds distally in a subpanels because we don't want any neutral current in the equipment grounding conductor (EGC) which can be dangerous.
* 16:00 If they are bonded at multiple locations, they will have current in both the ground and neutral, which is a dangerous situation. They are only connected at the FDM (first disconnecting means). He goes into this if further detail in another video that's linked in the description.
* 17:52 Review and summary.
Pretty late to this, but I can help answer 13:34. Having neutral disconnected from local ground can cause 'floating' ground, where neutral and thus your electrical systems ground is not the same potential as the ground under your feet. This can cause you to get zapped more often and put sensitive electronics in harms way when working on them.
Hello. I have PHEV vehicle that doesn't charge from my 110v outlet, but It charges from 110v outlet on my job warehouse. I opened the outlet and I saw it has Hot, Neutral and Ground. What can it be in my case?
If your house is old it probably has nob and tubing and that outlet doesn’t have a ground. Somebody might’ve put an outlet there that has a hole for the ground in the outlet itself, but the outlet itself might not have a ground or has lost the ground. Or the outlet that you’re speaking of has lost the neutral.
@williamrose7184 Thank you for this informations, the house is from 1940s, I checked few outlets, same problem. I measured voltage on them, between Hot and Neutral has 115v and between Hot and ground metal outlet box is around 112v. Can I measure the resistance between Ground and Neutral?
you should have the same voltage reading. That tells me something funky’s going on. Are you sure that the outlet at your job is 120 V and not 240? Second, is there a switch on the male cord from the car that switches between 120 and 240 V. Third. Bad grounding can cause your car not to charge so that could explain the 115 to 112 voltage problem. You should be reading 120 between the hot and the neutral unless you’re far away from the source or the wire size is very tiny. Being that the house was built in the 40s you could have a multitude of problems. What I would do is go to your electrical panel ad a 120 V outlet right at the panel and plug your car into that and see if it works. If it’s 120 V it should. I would put it on a 20 amp circuit and use 12 gauge wire.
Hi, EE student here (yet to have classes on this subject), just recently I was wondering why the ground and neutral on the "fist disconnect" were connected, I thought ground existed only so if something goes wrong, there's a better connection to the ground than the people around the equipment, I never realized it's just a big circuit and how it actually works, big thanks for the insightful lesson!
Huge props for covering this subject. Very important information most electrician overlook.
This video is utterly fantastic. Love the clarity. Confirmed some of what I already thought I knew, and learned about the secondary panels not having ground and neutral bonded (which totally makes sense now, thanks to this video!)
Please elaborate. The man went to great effort to teach people he doesn't know a topic that we field electricians quite frankly are in DIRE need of being taugh if my experience is any indicator. The man very humbly asked any who were more well versed, or better educated than himself to please speak up, as he seems to genuinely want to educate, not show off his brilliance before the masses. If he was off base then correct him. And be specific as he was spot on for the vast majority of it. Otherwise please keep you comments to yourself lest ye instil further doubt and confusion into an already long ignorant, completely misinformed and thoroughly confused group of people. Many of whom sincerely WANT to learn this shit so that we don't burn your f'ing grandmother's house down with our ignorance.
Put up or shut up.
You have a gift for making the difficult to understand clear and understandable. You are a great teacher!
This was the best explanation of this I’ve ever heard. I’m saving this video to watch again.
Wow, super helpful! I've always glossed over this my whole life while knowing enough to do home electrical work. Thanks much!
We also connect the neutral to the ground so that it will always have the exact same electrical potential as the ground we are standing on, this ensures safety for people using the electrical systems. Any metal bonded parts (fridge, pendant light, toaster etc) and any neutral wire are all safe for users during usage.
Ben, I really appreciate your time. Thanks for all you do for us!
Blue for neutral works for me, Here in the UK Blue IS neutral, Live is Brown and Green and yellow striped is ground.
We always use those colors for mains AC and only use Red/Black or Red/White for DC
You asked so nicely that I subscribed immediately. I also really appreciate learning things and you’re good at explaining them so I think this will work out well for all.
Yes, grounding will prevent buildup of static electricity. Static electricity is just built up potential, and you get shocked when you create a path to ground for it. If it's already grounded, it can't build up.
Thanks for adding the one answer that he wasn’t sure about. You make a good team. 👌🏼🙏🏼
Not only that, one can think of static electricity similar to lightning and grounding is for the same reason. Lightning is basically a discharge of static electricity between a storm cloud and the ground...
Back in the 80's I was on a project where we built isolated ground circuits for computers. We later found that we had up to 30v between neutral and ground and this was causing issues with and failure of the electronics which expected them to be at the same potential. The wires are basically antennae and will pick up any RF or static electricity and carry that. The solution was add a ground plane consisting of a grid of rods sunk into the earth and ground the outlets to that plane.
Bingo. The discussion starting about 9:30 is what really cleared it for me.
In case of a ground fault, and current flowing through ground wire, the breaker will not trip unless the ground wire is connected to the neutral wire. If ground wire is only connected to the dirt, breaker will not trip. Makes sense.
Thanks and subscribed.
I'm building an 8kw solar pv system, and this topic has confused me for weeks. Even when explained to me by other RE people, it just makes my head spin. This has cleared it up for me. I didn't know how, or understand why, I needed to know this. With 2 solar arrays and a wind generator, I just didn't get where and when I need ground rods and how I was suppose to know what to look for when accessing these ground/neutral points. Thanks very much, Benjamin. I really appreciate it. Lee
Never stop learning... i really dig these videos
Thanks sir, you're a good teacher and I got everything you've taught clearly.
Thank you! You did an exceptionally great job with explaining this to where just about anyone should understand. At least, help them to get closer to understanding what many make so difficult to grasp. I've was an industrial electronic technician for over 25 years, and during my career, I found so many issues and just couldn't make others understand the importance of grounding. I had one incident where an automation machine would just go haywire on its own. It took days to find the problem. The problem was the machine itself was creating enough electrical interference to disrupt feedback and, in return, make motors & controls to be unstable. I found the first grounding wire that was connected to the source (that was bonded) and ran a ground wire from the machine to that wire. The machine ran with no problems after that. I got much respect for "fixing" that problem. After that, I checked the ground 1st for any issues.. .lol. Your video will help a lot of people!
Well done!!! Thank you for the videos as they aid those who may be looking for CLEAR understanding to obtain it. The fact that your video had no background music and that you speak clearly and articulately, using and defining electrical terms where necessary, with diagrams, a.k.a. drawing, easily aid the listener, your audience to gain the main points of your explanations. WELL DONE!!!! If only we had more people using this forum who are equally effective as you are, there would be a greater interchange of useful knowledge being shared and obtained. KEEP UP THE GREAT STANDARD YOU HAVE SET!!!!! And again, thank you!!!!!
Hey man .A while back I mentioned Holt Enterprises, it seems like you have increased your knowledge. Excellent video. Awesome topic and a very very important one.
Excellent video. Suggestion - mention that these fault connection requirements are to avoid people being best path for current and thus avoiding electrocution. It is implied, but super important to reiterate.
You are an excellent teacher. Even I could understand and I am a visual learner but have tried to understand grounding and neutral relationships for some time. You helped me greatly. Thank you.
Excellent. Got my electrical ticket 40 years ago. Didn’t stay in trade. Work in hvac which is largely electrical troubleshooting. This is a great refresher
Just recently started wondering about why its wired this way, great timing for this video to come out. Thanks.
Google spying on us. Yesterday our instructor literally pointed at the power lines to explain neutral and ground. Even talking about effective ground circuit path. Basically, nearly word from word of Benjamin said. Sure enough, this video popped up on my Suggestion 🤣
Amazing explanation, and that diagram is extremely helpful and easy to follow!
I see why this video has over 1 million views! You are really good at explaining things! Thanks!
This is the clearest and easiest to understand explanation of this topic I have ever seen.
This way of how grounding works (from the grounded component earth wire through the neutral line back to AC transformer) ONLY applies to specific TN-earthing systems (TN-C and TN-CS).
It does actually not apply to TN-S and TT earthing systems, used in Europe and Asia (and US at gas stations ect. by exception).
In a TT-earthing system (common in Europe) the return fault current actually IS returned by going trough your premise ground rod trough the earth to the distribution AC-transformer ground rod connected to its starpoint or neutral wire. There is here NO link between the neutral line from the supply at your premise to the grounding/earthing wires in your installation. Because of the higher resistance of the earth soil the current will in a lot of cases not be high enough to trip your normal circuit breaker (overcurrent protection) while still being deadly dangerous. Therefore a RCD/GFCI-device covering your entire installation at the supply is mandatory in most countries, as it will trip much faster at a the existence of a ground fault current of 300mA/30mA.
When in a TN-C earthing system the neutral gets broken (by heavy weather at power poles for example) you get a dangerous situation because (1) the only return path is trough the soil with higher resistance and the installation does not always have a general RCD covering the entire installation and (2) with the lack of a neutral conductor the devices connected between the 2/3 phases and the in-house neutral are getting connected in serie leading to a dangerous abnormal high voltage on your 'grounded' equipment. Using a PEN-conductor (combined neutral and protective earth condictor) as in this video can be really dangerous if the PEN-conductor is broken upstream. In the UK/Australia this setup is called PME (Protective Multiple Earthing), but it basically the same as TN-C-S with additional ground rods along the way to reduce the electric potential created by the PEN-conductors themselves because of the long distances/resistance of the cheap conductor materials used.
So based on your earthing system, the ground rod at your premise is besides lightning strike protection possible also used as a conductor back to the transformer neutral trough the earth as part of the normal earthing system.
The explanation in this video only applies to common household installations in North America, but not to the rest of the world.
agreed.
The earth and neutral connection is not just for earth faults. It is also to stop floating neutrals. In Australia, without the MEN (Main Earth Neutral) Link, you can have an excess of 100v between ground and earth, creating a earth-neutral fault. Australia can have the issue where a neutral breaks, the fault current can leak through the earth rod to the neighbours earth rod and to use their neutral path.
@@Hunty49 in Aus its MEN or CMEN. combined multiple earthed network
"Because of the higher resistance of the earth soil the current will in a lot of cases not be high enough to trip your normal circuit breaker (overcurrent protection) while still being deadly dangerous."
It is voltage that is dangerous. The ground rod may have 90% of the mains voltage. TT is not used on some countries like Italy. It is unheard in Finland for example. Here everything new is TN-C-S, older ones are TN-C.
RCDs have nothing to do with PEN-faults. RCDs specifically cannot cut the PE/PEN wire. An RCD can be only used after the PE an N are separated.
@@Hunty49 If I understand you right, it sounds a lot like PME (Protective Multiple Earth) in the UK.
It would be nice if everyone some day respects the same naming conventions around the world for the same stuff :-)
Actually, neutral and ground are connected together on a ship when on generator or inverter, but not when connected to shore power. With shipboard generators or inverters, they are a power producing devices, hence need to have neutral/ ground connection. I once had to troubleshoot why a sophisticated Jennaire range worked on shore power but not on generator. The generator had no neutral/ground bond. I installed a proper jumper and bingo, range worked fine
It was not mentioned in this video, but the NEC requires the neutral to be bonded to the ground everywhere power is generated and transformed, as well as at the primary disconnect/service entry from the utility.
So it would make sense to bond the ground and neutral at a generator that is creating the power being used, as it is the source. If on shore power, the power being used is being generated elsewhere, and the neutral should be bonded at that source, not at the ship. This is because of the basic way electricity travels. In a loop. Grounding is done to provide a low resistance path back to the source in the event of a fault. So if a ship is pulling power from shore, and a fault occurs, you don't want the fault traveling through the ship, or the water around the ship while it attempts to return back to the source. You want to give it a straight path back, so the breaker, or fuse, on the hot leg of the source, opens as quickly as possible.
I really think that we missed the shop on the true concept our man was trying to get at!! You all out there on ships live a great an amazing life however , as anywhere dangerous… so thank you all for everyone’s input , knowledge etc.. but the basics of electrical current and risk of life / lives is what is being explained. I just moved onto mobile / manufactured home maintenance and damn what a complete different world I landed in!!! So I encourage anyone and everyone to just know the basics and appreciate anyone or anything that can help or make it safe for ALL!! Thanks Ben you are amazing I would love if I could contact you directly for info and help . Keep doing what you are doing . DeVry was nothing what I have learned here !!
No. Not always the case. I worked on a large ship that had a floating system. A floating star-point. All 3 phases were monitored to ground and would give an alarm if a ground fault developed. The theory was that if a you had fault you would get an alarm and respond and make the call if it was serious or not. This was to avoid nuisance trips on critical systems during important periods such as steerage into port or during storms.
Fantastic explanation!!!
Thanks for all of the combined knowledge guys! I learned a ton
I once had a service call for with an older boat tripping the newer gfi breaker on the dock.
The clothes dryer had a physical nuetral to ground connection, fixed that & still the gfi tripped & still had nuetral to ground continuity in the boat with Shorepower disconnected & genny off. I found the generator's nuetral output (that was physically tied to ground in genny) was connected directly to boats nuetral buss behind main panel in salon.
I wired the generator's nuetral output to a transfer switch so you could keep the generator neutral output open when connected to shore power.
Now the boat wouldn't trip the dock gfi & the boat had zero (OL) nuetral to ground continuity when boat was disconnected from shore, genny off, & inverter off
Hi Ben - I’m an electrical engineer and want to commend you for this outstanding video. One suggestion I have regards your use of the phrase “clearing the fault.” I think the average person would better understand the material were you to say something like “trips the breaker or ground fault interrupter.” Thanks again. Awesome work! -Jim
Good point. I didn't understand exactly what he meant by that. Thanks for clarifying.
1) i rarely subscribe to any channel and i never hit the notification bell. However, you answered a question for me that no one else seemed to be able to. So i subscribed and hit the bell. Thank you very much. BTW, your presentation is clear and concise, making even ppl like me able to listen and learn.
Benjamin, I am really enjoying your presentations, very logical, and you make it interesting and easier to follow... You have a real talent for this. Keep up the good work!
Thanks!
@@BenjaminSahlstrom I am in the process of harnessing my 3 phase 120/208Y in my shop for some CNC machines we have ordered. It will involve step-up transformer to 480V Delta. In the past, I've left this to the electricians but as an old mechanical engineer, understood "theory", decided to look into the practical applications myself.... Fascinating stuff!
@@jdevine40 Lets say that the neutral and ground cables are bonded toguether at the main panel. Now if a hot wire makes direct contact with the ground wire conductor What would happen? Does it cause a short circuit?
@@miguelac6872 Yes.
@@miguelac6872 it would go through the neutral and trip the breaker
18:25, Grounding is used to protect against lightening strikes and to remove "voltages accumulating on the electrical system". The metal buildings and panels can pick up static electricity so the grounding drains that off. The static can come from nearby overhead power lines, or the wind blowing over the metal surface; (maybe the wind comes from charged clouds?).
This was an excellent video!
Grounding is used to protect against step voltage, underground cable can't catch lightning. Lightning protection is used only for 3+ floors buildings and those wires are separated from earthing rods, as it has it's own long rod.
I was about to comment on this but then I found yours. Finally there is someone who understands lightening.
I can't understand why the murkiness surrounding lightning persists. Benjamin Franklin is credited with inventing the lightning rod. The vast majority of people mistakenly believe that lightning rods attract lightning. The truth is, lightning rods dissipate an otherwise building up of electrical potential, thereby preventing a lightning strike.
If lightning rods attract lightning it wouldn't make sense to place them on buildings, power poles, sub stations, etc. If lightning rods attracted lightning there would be a high number of reports of building and equipment damage.
The bonding to earth ground is for the purpose of preventing your toaster from developing a electrical potential on the chassis that differs from say your microwave to prevent electrical shock if you were to become the conductor between the two, for example.
The guy doing this video was right on the money up until the 12 minute mark.
@@Dmitrytln How does grounding mitigate step voltage? Isn't step voltage essentially caused by grounding? Do you mean touch voltage?
@@Dmitrytln Per the NEC: Electrical systems that are grounded shall be connected to earth in a manner that will limit the voltage imposed by lightning, line surges, or unintentional contact with higher-voltage lines and that will stabilize the voltage to earth during normal operation.
Besides lightning the grounding rods are there because there is capacitive electro-static coupling between the primary and secondary side of a transformer. The grounding rods placed on the secondary sides of transformers shunt these high voltages to earth ground so that they don't appear on the load side of the transformers.
Best video on the subject ever. All the others keep repeating the same ideas about neutral : "return path" but cannot explain why.
You explain so well, I'm subscribed. Keep up the great work
0:11:10 not primarily "lightning" but more to keep the common from developing a biased charge. Your household or even medium industrial commons and grounds are not going to handle even a mild lightning strike without taking damage that interrupts the continuity and contiguity of the wiring and connections. The grounding and bonding makes the un-charged lines all but invisible to lightning and the ground bond on housings and conduit will allow an arc of lightning to cascade through them to ground but the bonded ground is literally there to turn it all into "dirt" in lightning's view - to negate any bias in charge on the systems that arrive at homes, commercial and industrial properties. The simplest way to look at this is that the charges in the sky will slowly start to develop companion charges on the ground to couple to and if Billy Joe Bob Willie Mac Jim Jones doesn't believe in bonding and lets his tractor shed build up a charge, the lightning is gonna think his shed's charge is its soul-mate and nail it hard. Lightning rods work by exploiting this localized cultivated charge when it increases in power and they bridge from sky to ground just like the arc suppression grid in a breaker. The common bonding "stealths" your electrical system in your structure by homogenizing its entire charge AND the area around the localized grounds to all the other grounding points up and down the grid. Which will leave your tree standing there with a MASSIVE target on its head as the minerals in its bark and any enclosed growth areas with bark will carry the ground charge just like a lightning rod. This is also the single most important reason to ensure your roof isn't leaking.
This is similar to the explanation I was given when I asked an electrician why the engineers were having them permanently remove the lightning rod from a hospital. There is a calculus to be done on the odds of your little cable system encouraging lightning to strike it. Many of the old systems have been determined to increase the probability of strikes, while simultaneously being insufficient to contain the strike, and routing the strike around the roof where it otherwise would not be likely to spread.
This is a great video also your very lucky to have this kind of service. Here in toronto almost everything is overhead and the meter gets installed on the side of the house and then the panel is inside... We use EATON here and most panels separate the ground and neutral
I do like the setup I have. It varies from property to property in our area based on how old the setup is.
Wow.. ive been watching videos for weeks.. this is the only guy that explained it just like I needed to hear. Awesome content! Thank you for sharing!
Yet another fine example of the value of bonding in our lives. Delightful and informative video. Many thanks!!
Ben did not explicitly mention it - but in this video when he is talking about breakers tripping due to ground faults: He is not talking about GFCI safety devices (outlets, breakers, etc) function. Even for normal breakers to trip (exceeding 15, 20, 30, etc amps of current), the ground fault circuit needs a path to the neutral of the source. This is what Ben is covering in this video. That said, GFCI safety devices that trip at a much lower fault current (5 to 25ma), also need this ground path to eventually lead back to the neutral of the source.
Breakers trip due to too much current going through them. The path after that does not matter whether be the neutral or the ground path. Without a path, there is no current. I can't figure out what point Ben is trying to make.
@@thunderlips81he is trying to make the point that unless the ground system is bonded, it acts like a floating conductor. If unbounded/floating, the ground doesn't complete a circuit that will allow the breaker to trip (upon a ground fault specifically)
@@FliesLikeABrickOk thanks, got it. The wording through me off a little bit.
The gfci trips when there is a current imbalance between hot and neutral. Not related to earthing or egc. When the imbalance is greater than 5ma gfci trips.
@@djhatton6858 Right, but if current can't flow during a failure (because the fault path is too high-impedence to the generating station or bonded path), then the GFCI cannot trip. It is a subtle, but important point.
From one pragmatic nerd to another, I appreciate your full accounting of your experiences (tribulations) in figuring all of this out. It's great that you openly accept advice and even encourage it. From my experience, this shows above-average intelligence. You are a both a good student AND teacher. Thank you very much for sharing. I have learned a lot from watching your videos. I subscribed and recommended your channel to several other nerds. Take care, bro.
You are a Genius, not even experienced electricians or electrical engineers gave me such a clear detail explanation.
Loved this video! Really made me understand why the sub panel is grounded differently. All of your videos have been very helpful and easy to understand quickly. Thank you for your videos!!
At 8:40, you give the wrong definition for the term ‘ground fault.’ Please review the definition in the National Electrical Code. Not sure how you can make this correction in the video.
Guys suppose that we have unbalance phases in our electrical system, as a result our neutral wire carries certain amount of current back to the source let's say 20 A with 5 V to the transformer. Why do engineers say that connecting that neutral wire to a ground rod on the transformer will cause the neutral to be 0 V? Isn't voltage suppose to be energy per charged particle? If so, then how come those 20 A can make it to the transformer? Like with what energy per charged particle can those electrons get to the transformer if their potencial energy was taken ? I hope you can undestand my point and help me out with this question that nobody in colombia knows how respond to.
Let it be known! Electrical lord holt hath spoken!
Good job explaining. I needed a refresher course to remember how I built my off grid system. Must of been right because I'm still here after building it 26 years ago.
Benjamin, you're a fine teacher. Much appreciate your clear and straightforward explanations!
The very best, simplest clear correct explanation of grounding principle. There is no other video like this. Thanks a lot
Damn, finally I get an explanation for this after yrs. Seems electricians don't even know why they are connected. So the grounding rod is for lightning striking your electrical system and neutral is for faults. And they are bonded just incase lightning leaks into your fault system it will still have a path to the ground. because faults want to get back to the source but lightning wants to get to the ground. You are right. everyone seems to think as long as any part of the system is grounded somewhere that it's safe. It all makes so much sense now.
Definitely worth the 20 minutes. So clear and didn't oversimplify. Thank you Ben!
After many years of a vague understanding, this has made it clear in my mind! Thank you!!
glad I found your video's; they are informative and answering some questions I had as I am working on my panel. I watched a couple videos before I clicked on any of your links and when I finally did, I find that the tool ( gerber )that has been in my pocket for 6 years and I can't leave my house without is what you have linked in every video you do.... explains why I trust you know what you are doing....
Love these videos
Many years ago, the chassis of many tube-type radios and some TV’s were “hot.” The better ones used isolation transformers or filament transformers but some had series-connected tube filaments with the chassis one side of the circuit. Few of these devices actually had polarized plugs so there was a 50% chance that the chassis was carrying 120 volts AC with respect to actual ground. The only “protection” for users was insulated knobs and cabinets...a very dangerous situation.
When I was a kid my neighbor's house was struck by lightning. They were an elderly couple with a very old TV (this was in the mid-'80s so their TV was probably from '60s or '70s) and their roof-mounted TV antenna was what was actually hit. It blew up their TV! I always wondered how, I wonder if this was the reason?
@@mattsun9765 No, I don't think that mattered. A direct lightning strike to the antenna input of any TV would destroy it. It is *possible* to design an antenna input that would withstand it, but it would be very expensive, and TVs are made as cheaply as possible, because people buy by price.
In Europe those are called all current radios as they worked both with DC and AC. That also means no transformer was possible. Fortunately here the plugs were such that they cannot be used on modern grounded sockets (you would not want a grounded computer next to one). Some people do not know this and change the plugs (if the plug does not fit maybe there is a reason). The only way to run them safely and legally here is to use an external isolation transformer.
Excellent description of the need to tie earth ground and neutral together at the first disconnect. Then keeping them separate in all sub panels.
Thanks, your explanation was spot on. I had researched for a few hours before I finally found your presentation. Best explanation I could have had.
Vey goon showing us what’s going on thanks
Whenever I watch your video, I'm so familiar with your main panel right now!
Thanks for your great explanation about the grounding and bonding system.
I can't wait for your next actual example related to the topic that you'll plan.
Best explanation of the bonding/grounding issue to date. Thank you! I knew what I had to do, but not why!
Hey, cowboy, 1000s thanks for your explanation-- it was Simple and Direct. You're the 1st .channel I've been subscribed.
Great job on your diagram! These videos could possibly save a life or two.
As an easily trolled person and an engineer, I feel compelled to point out a few things. The likely reason you didn’t trip a breaker when you connected to a grounding rod is because there was too much resistance and therefore not enough current to trip a breaker. When you complete the circuit back to the proper path, there is a low enough resistance to generate a momentary current spike to trip the breaker. If you had a GFCI, you would have tripped it the instant you touched the grounding rod. Also... the electricity is not magically finding its way back to the breaker box through the ground... it is simply dissipating into the giant electron sink that is the earth on the peaks of the AC sine wave. Similar in principle to how you can static shock a metal object that isn’t grounded.. but on an almost infinite scale.
Better to go through the gnd wire than through you to gnd.
Question for you: if you had a ground that wasn't connected to neutral back at the panel, so a fault caused the ground to be hot but the breaker didn't trip...is this still somewhat safer than no ground at all? Isn't it better to have the electricity choosing the least resistant path (ground wire) than through someone who touched it at the appliance? Or...?
The electricity must complete the circuit with the transformer. It's not magic but it does it. Earth does not act as an infinite sink in the way you describe.
@@spruce_goose5169 So it would not be marginally safer to have an un-connected-to-neutral ground instead of no ground at all?
@@lhw4 for true safety what you want is for the breaker to trip, and you likely need the neutral bond for this to happen.
(Edited: I wrote something incorrect originally). If you touch a hot chassis due to fault, you are in parallel with the ground system resistance, and circuit theory tells us that you will still be presented with full voltage at the node (the point of the chassis you are touching).
Great video and AMAZING work explaining everything so well. I will eagerly be watching and supporting the channel.
Thank you for some excellent explanations re ground and neutral separation. I asked a couple electrician friends, and none of them could give me such a clear answer. Subscribed.