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So I mainly work with 120/208, but I am at a site with 277/480 and my journeyman told me that the neutral would shock me. I try not to be a smart ass, so I did not correct him, but the neutral is bonded to ground and therefore at zero potential, correct? I did make sure he was not talking about breaking a neutral after a load, which I know presents a shock hazard, and confirmed to just not touch the neutral.

Ordinarily, I would just write this off as him being a great teacher and looking out for my well-being, but this is not the first time I have heard this warning about 277/480 neutral being dangerous. The boss of the last company I worked for said the same thing and then went on about the center tap of the xfmr being ungrounded. Is this the same thing my current journeyman is worried about (he has been in the field almost 30 years) and is it uncommon now?

Another question I have is why some people call 277v a wild leg? This was not done by my current joruneyman, but it has been brought up a few times when talking to various people in and close to the trade. I learned about wild leg services when I was doing work in Indiana, and always took it as a high leg delta transformer which puts 240v phase to ground, where the other two phases are 120. At one site, I was on the roof and saw how the pole pigs were wired to get the high leg. In every 277/480 I have ever worked, the phase to ground voltage has always been the same.
 

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evil bastard
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So I mainly work with 120/208, but I am at a site with 277/480 and my journeyman told me that the neutral would shock me. I try not to be a smart ass, so I did not correct him, but the neutral is bonded to ground and therefore at zero potential, correct? I did make sure he was not talking about breaking a neutral after a load, which I know presents a shock hazard, and confirmed to just not touch the neutral.

Ordinarily, I would just write this off as him being a great teacher and looking out for my well-being, but this is not the first time I have heard this warning about 277/480 neutral being dangerous. The boss of the last company I worked for said the same thing and then went on about the center tap of the xfmr being ungrounded. Is this the same thing my current journeyman is worried about (he has been in the field almost 30 years) and is it uncommon now?

Another question I have is why some people call 277v a wild leg? This was not done by my current joruneyman, but it has been brought up a few times when talking to various people in and close to the trade. I learned about wild leg services when I was doing work in Indiana, and always took it as a high leg delta transformer which puts 240v phase to ground, where the other two phases are 120. At one site, I was on the roof and saw how the pole pigs were wired to get the high leg. In every 277/480 I have ever worked, the phase to ground voltage has always been the same.
You're right there's no high leg or wild leg in 277/480.

You're also right that that neutral is close to the same potential as ground, barring voltage drop. You could have 4-8 volts d.o.p. in large buildings. As long as the d.o.p. between neutral and ground stays under 5% it normally won't cause a problem.

But don't dog the guy for it, he most likely knows and is just trying to keep everyone safe. Of course, opening a neutral under load would put one of the neutral wires at full line potential.
 

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The two worst hits I have ever taken in my life were from 277 neutrals. Just learn good habits and never took copper even if the panels arent up yet. It will save you later on.
 

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A neutral can definitely shock you if you happen to get in series with it. An example would be you opening a junction box and finding the neutral splice falls apart easily so you try to put it back together, thinking it's a neutral and won't shock you. Once that splice is broken the white wire coming from the load is no longer a neutral, it's just an energised wire and there will exist potential between it and the neutral going back to the panel, as well as between it and the box, and the bonding wire. So if you touch that energised "neutral" while you're splicing it back together or to the box, yes, you will have a very bad time.

This is true of any neutral, not just a 277/480 neutral.
 

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Discussion Starter #5 (Edited)
You're right there's no high leg or wild leg in 277/480.

You're also right that that neutral is close to the same potential as ground, barring voltage drop. You could have 4-8 volts d.o.p. in large buildings. As long as the d.o.p. between neutral and ground stays under 5% it normally won't cause a problem.

But don't dog the guy for it, he most likely knows and is just trying to keep everyone safe. Of course, opening a neutral under load would put one of the neutral wires at full line potential.
Thanks, I figured as much, or that maybe he was thinking of some kind of weird corner ground setup or such not. So when the voltage drops, it is essentially flowing through the EGC to heat up the ground through eddy currents? What is d.o.p.? Distance of potential, or another name for voltage drop?

I would never be a jerk to my journeyman, so glad I followed him to this other company, he is a great teacher on the theory and practical side of the trade. This is the first quibble I have come across.

A neutral can definitely shock you if you happen to get in series with it. An example would be you opening a junction box and finding the neutral splice falls apart easily so you try to put it back together, thinking it's a neutral and won't shock you. Once that splice is broken the white wire coming from the load is no longer a neutral, it's just an energised wire and there will exist potential between it and the neutral going back to the panel, as well as between it and the box, and the bonding wire. So if you touch that energised "neutral" while you're splicing it back together or to the box, yes, you will have a very bad time.

This is true of any neutral, not just a 277/480 neutral.
I thought I made it clear in my OP, but yes, I know it is possible to be hit on a neutral that is carrying a load. I have even worked at some places that have been done over by hacks and have to check ground for return current path. My question was pertaining to unloaded neutral, such as at the lug at first means of disconnect.

I thank the posters reminding me of something I already know, and have actually been shocked completing a neutral path to ground, so know all too well.

I am the guy some dislike at my company reminding them of the 2014 change for handle ties on MWBC. They love sharing neutrals 'round here.
 

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Thanks, I figured as much, or that maybe he was thinking of some kind of weird corner ground setup or such not. So when the voltage drops, it is essentially flowing through the EGC to heat up the ground through eddy currents? What is d.o.p.? Distance of potential, or another name for voltage drop?

I would never be a jerk to my journeyman, so glad I followed him to this other company, he is a great teacher on the theory and practical side of the trade. This is the first quibble I have come across.

Edit: I thought I made it clear in my OP, but yes, I know it is possible to be hit on a neutral that is carrying a load. I have even worked at some places that have been done over by hacks and have to check ground for return current path. My question was pertaining to unloaded neutral, such as at the lug at first means of disconnect.

I thank the posters reminding me of something I already know, and have actually been shocked completing a neutral path to ground, so know all too well.

I am the guy some dislike at my company reminding them of the 2014 change for handle ties on MWBC. They love sharing neutrals 'round here.
Yes dop is difference of potential. If there's 5 volts of voltage drop on a circuit, you will see that 5 volts as difference of potential between the ground and neutral.
 

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Discussion Starter #7
Yes dop is difference of potential. If there's 5 volts of voltage drop on a circuit, you will see that 5 volts as difference of potential between the ground and neutral.
So for that voltage to drop, it must do some work? I'm assuming it just makes heat and a hum? Is this the case for every branch circuit, and the entire grounding system dissipates the heat quite readily, or is the voltage dropping through some other way?
 

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So for that voltage to drop, it must do some work? I'm assuming it just makes heat and a hum? Is this the case for every branch circuit, and the entire grounding system dissipates the heat quite readily, or is the voltage dropping through some other way?
I will weigh in only because it has been about twenty minutes since you posted and no "smarter" person has responded. I know you understand that the neutral is at GROUND potential because there is a physical connection at the service. However, the NEUTRAL is a circuit conductor AND a current carrier. As current flows through a resistance, and copper/aluminum has resistance and there is the load as well, as you said "SOME WORK IS DONE" to the extent that VOLTAGE is developed across the resistance. If you are testing far enough away from the circuit source there could be a difference of potential between your neutral and your ground.
 

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If you have a shared neutral, you could potentially have a "loaded neutral". You could turn one circuit off, but that neutral could be carrying current from other circuits as well. In which case it is not safe to break the neutral until all circuits are de-energized. You could end up with a 480 volt kick in the balls.
 

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So for that voltage to drop, it must do some work? I'm assuming it just makes heat and a hum? Is this the case for every branch circuit, and the entire grounding system dissipates the heat quite readily, or is the voltage dropping through some other way?
It mainly ends up as heat. That heat causes voltage drop. The longer the run and/or the more current the more voltage drop. All current carrying conductor experience this. So voltage drop applies to every single part of the distribution system including all branch circuits.

The grounding system doesn't do anything to dissipate this heat or voltage. Grounding or no grounding any branch circuit neutral with load will have a voltage to ground.

And as other have said a broken neutral will become live up to the normal phase to ground voltage.

In fact in Europe it is common if not required to switch the neutral when the hot is opened at any circuit breaker for the exact reasons stated in this thread.
 
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