Thanks Mike for great help. I have heard many times fine a problem solved it and use it to help others. I have some of your books and dvds. All the information has been very helpful.
Mike’s story about that young man getting killed working in that sign makes me so angry. I guarantee the reason why he was working in that sign hot is because the company didn’t want to turn off the power for five minutes because it would shut down a register or turn off a light or a computer or something and be an inconvenience. I’ve been in this situation MANY times where I would have to wire something up hot because the company I was working for didn’t want to turn off the light for a few minutes. Ridiculous and unacceptable and these companies need to be held accountable. I don’t care if I have to turn off a breaker and your computer has to reboot and your customer has to wait five minutes. 🤬
Well, we don't know that's the case and also there has to be a means of disconnect on or near a sign itself. I had a guy in a company I used to work for that died this same way. The switch at the sign was on, which it shouldn't have been. I'd attribute it to poor safety protocols for our company. Where I work now we have a ZERO hot work policy.
Right but when us regular guys ask electricians, can you hookup a 220/120v sub panel using 2 conductors and a ground, and they say just drive a ground rod you’re good… makes me want to jump off a cliff
To make sure I understand. The example of the crossed neutral - there were two mistakes that lead to the electrocution? The first being a crossed neutral and the second tying the transformer equipment ground to the X0 transforme neutral connection creating the objectionable current path. Is this correct?
I’m not an expert but Isn’t it a code violation to have voltages from two separate panels in the same junction box to begin with? I know that the same thing can happen with objectionable current in a single panel with neutrals being crossed!
I did not know the neutrals could kill someone. I am on alert now and be careful to look for crossed neutrals. Helpful and insightful real stories. E;ectricity is serious, and I am in awe. I am saddened for the lives lost, good people doing their work. Question: I am building my house. From the conductors coming into the meter, I was to put a service feeder ( main panel outside the house in a column), and I bond the neutral and the ground there. Would I need to carry four wires from the main panel to the panel into the house? and should I click it there again or have it separate from a neutral bus bar from a ground bus bar? Appreciate it. God bless
At around 2:33 Jacob asked if the case was energized and you said it's not. It's not because there's no voltage even though it's carrying current? I'm asking in order to understand the definition of "energized". I would have thought that it was energized.
I’m not sure how significant it might be, but a number of those surge suppressor power strips use Metal Oxide Varistors (MOVs) to shunt surges in three modes: L-N, L-G, and N-G. But, MOVs have a measurable *_leakage current,_* which will flow on the ground conductor. If you have enough of these on a circuit, I’m wondering if this might be a problem? Ditto for power supplies that filter common mode noise by placing a _Class Y_ capacitor between: L-G and N-G. Presumably these same situations could cause nuisance tripping of GFCI breakers, right?
GFCI's trip between 4 - 6 mA, way above the possible 'leakage current' of MOV and filters in power supplies. So this has not shown to be a problem with GFCI's. If you 'know' otherwise, please get me the technical documents.
After watching the video, I'm really feeling paranoid. Because, the neutral point may cross as Brian said and seen numerous times! How about using 'PPE' like gloves, will that prevent these sort of hazards while working? If so then what should be the minimum category? Thank you Mr. Mike, Mr. Eric Mr. Brian and all the members.
The voltage on the green grounding conductor is NOT zero. It is raised at some potential (reference to "earth") as a result of the "Objectionable Current. It may be a small amount but it exists a potential greater than zero. To say it is zero diminishes the importance of preventing the problem.
@@MikeHoltNEC Thanks for the link, stray voltages are around us for sure! Frightening to me having a pool! The problem I was referring to in my comment was the 115V motor using the protective ground instead of neutral. My point was that the example fan motor, say 1HP, will be drawing ~7A through a section of #8 wire and that conductor has a resistance, admittedly small so the cabinet of that equipment will be above the potential of other equipment and water pipes referenced to earth via other means. In doing a back of napkin calculation, admittedly at 7A it will probably be very small less than a few 100 mv assuming the protective ground is well engineered with sizable conductors. But it could be much higher if there was a fault or very large load returning that way. Thanks for the videos. Very informative.
@@rhyoliteaquacade If it's a ground fault, the protection device clears it, so no voltage no problem. If it's a larger load, then the N-E voltage will be so small that it's also a moot point. Try some napkin calculations to understand my video comments on objectional current.
This goes a long way to answering a question I have always had about shock risk due to bonding a sub panel; how can that condition shock me? I know bonding a sub panel causes certain issues, and so I don't do it, but it won't shock you like I always hear. Touching chassis with one hand and another chassis or neutral with the other won't shock you if you bond a sub panel because you are in parallel with a zero impedance conductor. So any current going through you at that point is negligible; you won't feel it.
277 neutral wire should be grey wire and 120 neutral is white. Pull appropriate colored wires people. In addition 277 circuits should never share the same raceway as 120. Also, I’ve made it a practice to assume every wire is hot even if I turned off the breaker and checked for voltage and current. And who ever twist’s wire with their bare hands? That’s what lineman’s pliers are for.
Your saying that using an equipment ground(that's bonded to metallic box/conduit) as neutral, that the box and raceway won't be energized? A neutral can carry current when the circuit is closed and the load is unbalanced. So if your neutral and ground are bonded past the service and your raceway system is grounded, isn't their a possibility that the equipment could carry current and be a shock hazard(hence be energized)? Also, when you were talking about the potential between neutral and phase leg and you stated that the neutral has no voltage, in an ac system the polarity alternates. So 240° into the voltage sine wave the neutral will have measurement of -120V, right? For some reason when you open a circuit voltage always sits on the hot side and I don't know why that is.
On a residential, single phase, (L/N/L, Hot/Neutral/Hot), 200 Amp service panel with a UFER GROUND, with 100 Amps of loads turned ON (50/50 per hot leg), what is the MAXIMUM OBJECTIONAL AMPS/current acceptable to travel/return back to the utility VIA the UFER ground? (Answer of ZERO is NOT reality. A small current ALWAYS finds it's way out the UFER. HOW MUCH IS ALLOWED PLEASE?)
The return current via any grounding electrode is simply a function of physics. There is not way to limit this and the NEC had no reason to establish a limit. So the answer is 'no limit.
@@MikeHoltNEC O.K. Then how about this?: At main panel, since Neutral and Ground are bonded, some return path electron currents do take the ground path back to the utility. What then is MAX PERCENT% of total return current flow allowed on the bldg GROUND, before utility needs to come fix their neutral? 1%?, 2%?, 5%???
Love these Videos Mike but there is absolutely voltage on a neutral wire and its strange that this view persists. If the neutral wire is connected to source properly, which is grounded, with near zero impedance then there will be no voltage between between ground and the neutral. The neutral and the hot are mirror images of each other. The only difference is that the neutral is grounded which means that the potential between the neutral and the ground will be zero but only when things are connected correctly. During the video you try to make the point that the voltage drop across the load will be 100% and this is why the voltage is zero but this is not correct because this statement assumes the impedance of the neutral line between the load and the source is near zero. If there is any resistance in the neutral path to ground (or source transformer which is grounded) then the potential between the neutral wire and ground will not be zero. This can be easily calculated with series resistance calculation. Lets say you have a 24 ohm load which would pull 5 amps in a 120V system under properly wired conditions. Now lets assume the neutral wire on this circuit was not tightened down properly or connected improperly at a junction box or the panel and maybe has been arching a bit so carbon has built up and now there is an effective 24 ohm resistance at part of the return path (I picked 24 to make the math simple) This scenario will lead to two loads in series with a total of 48 ohms. Ohms law will tell us that total current in the circuit will be 2.5 amps instead of the 5 amps it should be. What are the implications of this. The motor will run slower and its voltage drop will now be 60 volts instead of 120 volts and the neutral wire will have a potential of 60 volts between the motor and the location of the faulty wiring. Even worse, if the neutral wire is disconnected, ie floating, then there will be infinite resistance for the return path and the neutral wire will be at 120 volts! Sadly this is what happened to your acquaintance. The point here, is that neutral wire is zero voltage relative to ground if the neutral wire has a near zero resistance path back to the source which is grounded. Assuming that the neutral is correctly wired though can be a costly mistake. The only way to ensure the voltage on a neutral wire is zero volts, relative to ground, is to measure it yourself prior to working on the circuit.
Thank you so much for this episode. Our new construction home has current on the ground wire and high enough magnetic fields in some circuits and switches that my electro-sensitive partner suffers. Most of the pros to whom I have mentioned this ground current and 5+ milligauss (magnetic field) readings, just shrug and say that some current on the ground wire is 'normal'. I will point our electricians to this video to reinforce that there is a safety as well as health consideration and not just alarmism from an overly sensitive client. We suffer meanwhile. What I would like to see more of are troubleshooting tips for the folks who are trying to track down such wiring problems, which are likely NEC code violations after all, right? Visual inspection of each junction box is one way. I fear my mind will get overloaded when I look at all the conductors for the multi-way switches. Shouldn't electrical inspectors at least take a clamp ammeter reading of the ground wire? I have also checked the clamp current ammeter on the romex wire (which includes ground, neutral and hot) and even some of *these* show 20--30 milliamps of net current. My understanding is that such objectionable current can stem from a few other issues other than mishandling the neutral and ground, such as (a) CATV lines (which are connected to that same ground), (b) faulty device or appliance and (c) maybe incoming from neighbors if the ground was attached to metal municipal water pipes.. These would appear to not be the electrician's responsibility so it gets murky who can find & fix. Thanks for all the great work you folks do.
@@Nahum17good I get you were being sarcastic, but Mike is a different breed. He has first-hand witnessed people getting killed by stupid electrical mistakes and that shit probably haunts him forever. Guys like you and me, yea, we'll get a good waker upper here and there, but we're extremely lucky that we're not one of Mikes case studies.
![Grounding, High Impedance [250.36, 2020 NEC]](http://i.ytimg.com/vi/XJs-FYRR3xg/mqdefault.jpg)
![Grounding, High Impedance [250.36, 2020 NEC]](/img/tr.png)
![Grounding, Auxiliary Grounding Electrode [250.54, 2020 NEC]](http://i.ytimg.com/vi/gg4wBI7bWgI/mqdefault.jpg)
started my xmas day w this video~ WOW - what a gift! serious
Always a pleasure and inspiration to watch a Mike Holt video.
Thanks Mike for great help. I have heard many times fine a problem solved it and use it to help others. I have some of your books and dvds. All the information has been very helpful.
Thank you and have a nice day!
2:37 the case is absolutely energized. NEC "connected to a source of voltage"
Mike’s story about that young man getting killed working in that sign makes me so angry. I guarantee the reason why he was working in that sign hot is because the company didn’t want to turn off the power for five minutes because it would shut down a register or turn off a light or a computer or something and be an inconvenience. I’ve been in this situation MANY times where I would have to wire something up hot because the company I was working for didn’t want to turn off the light for a few minutes. Ridiculous and unacceptable and these companies need to be held accountable. I don’t care if I have to turn off a breaker and your computer has to reboot and your customer has to wait five minutes. 🤬
Well, we don't know that's the case and also there has to be a means of disconnect on or near a sign itself. I had a guy in a company I used to work for that died this same way. The switch at the sign was on, which it shouldn't have been. I'd attribute it to poor safety protocols for our company. Where I work now we have a ZERO hot work policy.
im just a regular jackoff and not an electrician, but you guys made this idea pretty easy to understand for this layman.
Right but when us regular guys ask electricians, can you hookup a 220/120v sub panel using 2 conductors and a ground, and they say just drive a ground rod you’re good… makes me want to jump off a cliff
To make sure I understand. The example of the crossed neutral - there were two mistakes that lead to the electrocution? The first being a crossed neutral and the second tying the transformer equipment ground to the X0 transforme neutral connection creating the objectionable current path. Is this correct?
Yes!
I’m not an expert but Isn’t it a code violation to have voltages from two separate panels in the same junction box to begin with? I know that the same thing can happen with objectionable current in a single panel with neutrals being crossed!
Nope, see 300.3(C)(1).
I did not know the neutrals could kill someone. I am on alert now and be careful to look for crossed neutrals. Helpful and insightful real stories. E;ectricity is serious, and I am in awe. I am saddened for the lives lost, good people doing their work. Question: I am building my house. From the conductors coming into the meter, I was to put a service feeder ( main panel outside the house in a column), and I bond the neutral and the ground there. Would I need to carry four wires from the main panel to the panel into the house? and should I click it there again or have it separate from a neutral bus bar from a ground bus bar? Appreciate it. God bless
Yes, you need to carry 4 wires into the panel inside. The neutral and ground should be on different bus bars after they have been bonded.
At around 2:33 Jacob asked if the case was energized and you said it's not. It's not because there's no voltage even though it's carrying current? I'm asking in order to understand the definition of "energized". I would have thought that it was energized.
Send me an email, Mike@MikeHolt.com
you did not explain when you joined the building neutral and all the light were bright, how else would you make the lights equally bright?
Have a neutral for each circuit.
Professor Mike. I just wonder what is the difference between watts and voltage. What can cost a burn to an electrical circuit equipment?
From local Cambodia
Please check this out on the Internet.
Great discussion!
I’m not sure how significant it might be, but a number of those surge suppressor power strips use Metal Oxide Varistors (MOVs) to shunt surges in three modes: L-N, L-G, and N-G. But, MOVs have a measurable *_leakage current,_* which will flow on the ground conductor. If you have enough of these on a circuit, I’m wondering if this might be a problem? Ditto for power supplies that filter common mode noise by placing a _Class Y_ capacitor between: L-G and N-G. Presumably these same situations could cause nuisance tripping of GFCI breakers, right?
GFCI's trip between 4 - 6 mA, way above the possible 'leakage current' of MOV and filters in power supplies. So this has not shown to be a problem with GFCI's. If you 'know' otherwise, please get me the technical documents.
After watching the video, I'm really feeling paranoid. Because, the neutral point may cross as Brian said and seen numerous times! How about using 'PPE' like gloves, will that prevent these sort of hazards while working? If so then what should be the minimum category?
Thank you Mr. Mike, Mr. Eric Mr. Brian and all the members.
If someone wanted to do that, just get gloves rated for the voltage expected.
Brian is a bser
It's easy You can only test voltage with parallel connections with a volt tester You must use series on the hot legs to test for amps
The voltage on the green grounding conductor is NOT zero. It is raised at some potential (reference to "earth") as a result of the "Objectionable Current. It may be a small amount but it exists a potential greater than zero. To say it is zero diminishes the importance of preventing the problem.
Preventing what problem? See th-cam.com/video/pAs_FmdxXhQ/w-d-xo.html
@@MikeHoltNEC Thanks for the link, stray voltages are around us for sure! Frightening to me having a pool! The problem I was referring to in my comment was the 115V motor using the protective ground instead of neutral. My point was that the example fan motor, say 1HP, will be drawing ~7A through a section of #8 wire and that conductor has a resistance, admittedly small so the cabinet of that equipment will be above the potential of other equipment and water pipes referenced to earth via other means. In doing a back of napkin calculation, admittedly at 7A it will probably be very small less than a few 100 mv assuming the protective ground is well engineered with sizable conductors. But it could be much higher if there was a fault or very large load returning that way. Thanks for the videos. Very informative.
@@rhyoliteaquacade If it's a ground fault, the protection device clears it, so no voltage no problem. If it's a larger load, then the N-E voltage will be so small that it's also a moot point. Try some napkin calculations to understand my video comments on objectional current.
This goes a long way to answering a question I have always had about shock risk due to bonding a sub panel; how can that condition shock me? I know bonding a sub panel causes certain issues, and so I don't do it, but it won't shock you like I always hear. Touching chassis with one hand and another chassis or neutral with the other won't shock you if you bond a sub panel because you are in parallel with a zero impedance conductor. So any current going through you at that point is negligible; you won't feel it.
Please watch MikeHolt.com/Fundamentals I think you'll like that video as well.
Sorry I meant 270° into the voltage wave the voltage should be -120v.
277 neutral wire should be grey wire and 120 neutral is white. Pull appropriate colored wires people. In addition 277 circuits should never share the same raceway as 120. Also, I’ve made it a practice to assume every wire is hot even if I turned off the breaker and checked for voltage and current. And who ever twist’s wire with their bare hands? That’s what lineman’s pliers are for.
Excellent comment
Your saying that using an equipment ground(that's bonded to metallic box/conduit) as neutral, that the box and raceway won't be energized? A neutral can carry current when the circuit is closed and the load is unbalanced. So if your neutral and ground are bonded past the service and your raceway system is grounded, isn't their a possibility that the equipment could carry current and be a shock hazard(hence be energized)? Also, when you were talking about the potential between neutral and phase leg and you stated that the neutral has no voltage, in an ac system the polarity alternates. So 240° into the voltage sine wave the neutral will have measurement of -120V, right? For some reason when you open a circuit voltage always sits on the hot side and I don't know why that is.
On a residential, single phase, (L/N/L, Hot/Neutral/Hot), 200 Amp service panel with a UFER GROUND, with 100 Amps of loads turned ON (50/50 per hot leg), what is the MAXIMUM OBJECTIONAL AMPS/current acceptable to travel/return back to the utility VIA the UFER ground? (Answer of ZERO is NOT reality. A small current ALWAYS finds it's way out the UFER. HOW MUCH IS ALLOWED PLEASE?)
The return current via any grounding electrode is simply a function of physics. There is not way to limit this and the NEC had no reason to establish a limit. So the answer is 'no limit.
@@MikeHoltNEC O.K. Then how about this?:
At main panel, since Neutral and Ground are bonded, some return path electron currents do take the ground path back to the utility. What then is MAX PERCENT% of total return current flow allowed on the bldg GROUND, before utility needs to come fix their neutral? 1%?, 2%?, 5%???
@@BYENZER Doesn't work that way, watch th-cam.com/video/mpgAVE4UwFw/w-d-xo.html
@@MikeHoltNECEvery house i work on, that has a UFER Ground, i put a clamp ampmeter around the panel's UFER. UFER ALWAYS HAS SOME CURRENT. Always!
@@BYENZER Correct, watch th-cam.com/video/a_nv_Q9WbeE/w-d-xo.html
Love these Videos Mike but there is absolutely voltage on a neutral wire and its strange that this view persists. If the neutral wire is connected to source properly, which is grounded, with near zero impedance then there will be no voltage between between ground and the neutral. The neutral and the hot are mirror images of each other. The only difference is that the neutral is grounded which means that the potential between the neutral and the ground will be zero but only when things are connected correctly. During the video you try to make the point that the voltage drop across the load will be 100% and this is why the voltage is zero but this is not correct because this statement assumes the impedance of the neutral line between the load and the source is near zero. If there is any resistance in the neutral path to ground (or source transformer which is grounded) then the potential between the neutral wire and ground will not be zero. This can be easily calculated with series resistance calculation. Lets say you have a 24 ohm load which would pull 5 amps in a 120V system under properly wired conditions. Now lets assume the neutral wire on this circuit was not tightened down properly or connected improperly at a junction box or the panel and maybe has been arching a bit so carbon has built up and now there is an effective 24 ohm resistance at part of the return path (I picked 24 to make the math simple) This scenario will lead to two loads in series with a total of 48 ohms. Ohms law will tell us that total current in the circuit will be 2.5 amps instead of the 5 amps it should be. What are the implications of this. The motor will run slower and its voltage drop will now be 60 volts instead of 120 volts and the neutral wire will have a potential of 60 volts between the motor and the location of the faulty wiring. Even worse, if the neutral wire is disconnected, ie floating, then there will be infinite resistance for the return path and the neutral wire will be at 120 volts! Sadly this is what happened to your acquaintance. The point here, is that neutral wire is zero voltage relative to ground if the neutral wire has a near zero resistance path back to the source which is grounded. Assuming that the neutral is correctly wired though can be a costly mistake. The only way to ensure the voltage on a neutral wire is zero volts, relative to ground, is to measure it yourself prior to working on the circuit.
Please watch MikeHolt.com/NEV
Who is Jacob?
A young person off screen.
MikeHoltNEC Why is he off screen and what his story? Is he a apprentice or journeyman or master or up coming master?
Thank you so much for this episode. Our new construction home has current on the ground wire and high enough magnetic fields in some circuits and switches that my electro-sensitive partner suffers. Most of the pros to whom I have mentioned this ground current and 5+ milligauss (magnetic field) readings, just shrug and say that some current on the ground wire is 'normal'. I will point our electricians to this video to reinforce that there is a safety as well as health consideration and not just alarmism from an overly sensitive client. We suffer meanwhile.
What I would like to see more of are troubleshooting tips for the folks who are trying to track down such wiring problems, which are likely NEC code violations after all, right? Visual inspection of each junction box is one way. I fear my mind will get overloaded when I look at all the conductors for the multi-way switches.
Shouldn't electrical inspectors at least take a clamp ammeter reading of the ground wire?
I have also checked the clamp current ammeter on the romex wire (which includes ground, neutral and hot) and even some of *these* show 20--30 milliamps of net current.
My understanding is that such objectionable current can stem from a few other issues other than mishandling the neutral and ground, such as (a) CATV lines (which are connected to that same ground), (b) faulty device or appliance and (c) maybe incoming from neighbors if the ground was attached to metal municipal water pipes.. These would appear to not be the electrician's responsibility so it gets murky who can find & fix.
Thanks for all the great work you folks do.
Sounds like a power ground too
Good reasons to always be checking for power when you open jboxes, enclosures etc. trust nothing and nobody.
I feel like a rich man having 4 prong dryer and range receptacles
If 277v neutrals were a different color than 120v neutrals, this would save lives. Maybe a 2023 code change? Hmmmmm......
The NEC requires 277V and 120V neutrals to be different color, see 200.6.
Sorry! That was meant as sarcasm!
@@Nahum17good Okay, have a great day.
@@Nahum17good lol, to be fair i didnt pick up on your sarcasm either
@@Nahum17good I get you were being sarcastic, but Mike is a different breed.
He has first-hand witnessed people getting killed by stupid electrical mistakes and that shit probably haunts him forever.
Guys like you and me, yea, we'll get a good waker upper here and there, but we're extremely lucky that we're not one of Mikes case studies.
I have people all the time that don’t know how to use a voltmeter that called me
Objection this is hearsay your honor.. this video evidence has not been submitted before the court. 😜
Jacob can’t catch a break lol
That why we have arch faul
Nope, AFCI does not respond to Objection Currents.
I’ve been a fan but this is wild. I started from a reasonable point of the drawing. This mf making his own ckts and problems.
Are you an electrician? All of the examples are 'real life' conditions that happen out in the field.
@@MikeHoltNEC yes sir. Let me rewatch and see if I come to a different conclusion.
At 4.14 I don’t understand why there is somebody on the panel that doesn’t understand how a meter works/ difference in potential.
And somebody on the panel differentiated from case ground that they think carry current. Unless I’m wrong from the graphic.
I don't understand your statement about 'case ground'. This is not a term we used in the video.
funny to see man talking about something he really dont understand
You don’t understand