round house neutral under load

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zappy

zappy

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So we're having a safety meeting, a electrician died because he thought because he turned off the circuit the neutral was dead also. well there were still two other circuits on that neutral and he got shocked. So I was wondering if he put a tick tracer on the neutral would it have showed voltage? I asked this question at the meeting and got various answers. what about using a voltage tester to ground, Whould that show voltage? Thank you for your help.
 
ptonsparky said:
I’ve had a non contact voltage tester show No Voltage when we knew it was present. Don’t rely on them.

Yes, a meter will show voltage to ground when connected to an open neutral. It is an open circuit. No different than measuring voltage across an open switch.
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To state it another way:
No voltage will be measurable until the neutral is disconnected from the bar. By the, it may be too late.
 
round house neutral under load

I think the keywords here are under load.

Taking voltage is one thing, getting caught in the load is a whole different ballgame. As the poor guy found out. RIP.
I blame the person before him for not identifying the circuit(s). 3 phase panel with single pole circuits should immediately call in to question whether or not there are shared neutrals. IMO.
 
zappy said:
So we're having a safety meeting, a electrician died because he thought because he turned off the circuit the neutral was dead also. well there were still two other circuits on that neutral and he got shocked. So I was wondering if he put a tick tracer on the neutral would it have showed voltage? I asked this question at the meeting and got various answers. what about using a voltage tester to ground, Whould that show voltage? Thank you for your help.
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Until you disconnect conductors, that neutral is going to show little or no voltage with a volt meter. What little may be shown is the voltage drop on the neutral itself.

If you clamp an ammeter on it before opening any connections and it shows anything significant - definitely has load on it. If shows a very low reading, might make you wonder if it is a phantom reading of some sort or not. Still possible to have "balanced loads" and little or no neutral current though, but once opened you now throw the balance off and can see full line to neutral voltage within what you disconnected.
 
zappy said:
So we're having a safety meeting, a electrician died because he thought because he turned off the circuit the neutral was dead also. well there were still two other circuits on that neutral and he got shocked. So I was wondering if he put a tick tracer on the neutral would it have showed voltage? I asked this question at the meeting and got various answers. what about using a voltage tester to ground, Whould that show voltage? Thank you for your help.
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That is why current code requires a handle tie or common trip breaker for all feeds which share a neutral.
 
kwired said:
If it were because he opened a neutral there would have been 277 volts to ground as well as to the "home run" neutral conductor.
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Yep, that will do it. And this is one of the reasons I limit my practice to residential only. 120V usually won't do any harm if you touch it, but if you touch 277V, you're done.
 
jeff48356 said:
120V usually won't do any harm if you touch it, but if you touch 277V, you're done.
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Don't rely too heavily on this concept. 120 volts is more than enough to cause a fatal shock. Much depends on how you touch it, and whether the touch results in muscle contractions that force your hand to more firmly grip the energized metal. I once heard a man mention that he remains alive because the shock caused a complete loss of muscle control, and the weight of his falling body pulled his hand away from the energized component. Actually, he fell off the ladder, and that fall might have resulted in greater harm than the shock itself.

 
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jeff48356 said:
Yep, that will do it. And this is one of the reasons I limit my practice to residential only. 120V usually won't do any harm if you touch it, but if you touch 277V, you're done.
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Add. I've been bit by 277 while kneeling in the mud. I'm here. Honestly, other than the burn mark on my finger and sore neck muscles, I couldn't tell the difference between it and 120. Both hurt.
 
jeff48356 said:
Yep, that will do it. And this is one of the reasons I limit my practice to residential only. 120V usually won't do any harm if you touch it, but if you touch 277V, you're done.
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I have to agree with the others. 277 has a better chance of being more harmful - if all other conditions are identical, but those other conditions always vary some. Grab that 277 line while standing on concrete with reasonably clean and dry rubber composition soles on your footwear, you probably do get a shock, may not be too severe but will feel something. Now put on similar footwear but has been worn a lot and been sweaty many times before - they likely are more conductive and the severity of the shock gets worse.

You think you are invincible because you survived that 277 volt shock, so when working on 120 volts, you happen to be leaning on something well grounded and is wet - it ends up killing you, all because low enough resistance path and a path through right part of body happened all at the right moment.
 
jeff48356 said:
Same reason as AFCI's -- to line the greedy pockets of the manufacturers of such devices.
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I do think many 2017 GFCI requirements were for that reason more so than there was a real need from safety perspective.

If you are going to throw "what if" out there as justification then there should be GFCI for everything. In the past GFCI has only been required in situations where statistically there have been more shock/electrocution incidents. In particular in situations involving 5-15 and 5-20 receptacles/cord caps, which have a tendency to end up missing EGC's on cord caps for various reasons. If there were no missing EGC's GFCI would not have as much necessity as a ground fault would ordinarily trip standard overcurrent devices if there is a good return path.
 
The only guy in my know associations that was killed was from cutting a (what was thought to be dead) neutral wire on a 277/480 feeder.
 
kwired said:
I do think many 2017 GFCI requirements were for that reason more so than there was a real need from safety perspective.

If you are going to throw "what if" out there as justification then there should be GFCI for everything. In the past GFCI has only been required in situations where statistically there have been more shock/electrocution incidents. In particular in situations involving 5-15 and 5-20 receptacles/cord caps, which have a tendency to end up missing EGC's on cord caps for various reasons. If there were no missing EGC's GFCI would not have as much necessity as a ground fault would ordinarily trip standard overcurrent devices if there is a good return path.
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Exactly! With that in mind, I find it ridiculous that we now need a GFCI breaker to power the line for a hard-wired dishwasher. Same goes for GFI protection for the outlet in the garage ceiling for a door opener, laundry outlet when not near a sink and hidden behind the appliances, or receptacles in an unfinished basement for sump pumps, HVAC equipment, or water heater motors. Single non-GFI receptacles for each of these items should suffice, as they have for decades without problems.
 
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