Open service neutral.

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Miguel c

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If the grounded (neutral) service conductor is open or missing, objectionable neutral current will flow on metal parts of the electrical system. This potential electrical shock condition is of particular concern in buildings that contain swimming pools, spas, and hot tubs. In other words If the grounded (neutral) service conductor is open, neutral current will flow onto the metal parts of the electrical system.
The question is:
How does the NEC protect people under these circustances?
If the neutral is open a voltage gradient is spread accross the earth, someone could get electrocuted.
What if I don't realize the neutral is open and current is returning to the source through the earth?
Wouldnt people outside get electrocuted since the earth is energized?
 

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IMO, this is one reason why we bond pools, spas, hot tubs and ORs. Personally I believe code should stipulate that bond wires not exceed 0.2 ohms in these locations in that current may flow through the bonding system seaking a path back to the POCO's transformer.

Outside of these areas the NEC does not offer much protection of that other than eliminating some sources of remote earth within the building accomplished via grounding electrode requirements whereby pipes, rebar, structural steal, and the like are bonded to the main ground bar.

Humbly I say "not much" in that the code does not require the bonding of iron gas piping, makes exceptions for rebar and allows the disconnection of grounding electrodes to manage objectionable current.
 
Miguel c said:
If the grounded (neutral) service conductor is open or missing, objectionable neutral current will flow on metal parts of the electrical system. This potential electrical shock condition is of particular concern in buildings that contain swimming pools, spas, and hot tubs. In other words If the grounded (neutral) service conductor is open, neutral current will flow onto the metal parts of the electrical system.
The question is:
How does the NEC protect people under these circustances?
If the neutral is open a voltage gradient is spread accross the earth, someone could get electrocuted.
What if I don't realize the neutral is open and current is returning to the source through the earth?
Wouldnt people outside get electrocuted since the earth is energized?
Click to expand...
That doesn't happen just because you lose a neutral. If the neutral isn't bonded to the metal enclosure, then there would be a hazard as there would be no fault clearing return path in the case of a ground fault. But just losing a neutral doesn't automatically put voltage on metal objects if bonded correctly.
 
Little Bill said:
That doesn't happen just because you lose a neutral. If the neutral isn't bonded to the metal enclosure, then there would be a hazard as there would be no fault clearing return path in the case of a ground fault. But just losing a neutral doesn't automatically put voltage on metal objects if bonded correctly.
Click to expand...
If you open the service neutral, there will most likely be hazardous voltages on everything connected to the electrical system unless you happen to have a common metal underground water pipe as the grounding electrode...in that case you probably won't even know the that neutral is open. The other grounding electrodes cannot flow enough current to prevent all of the non current carrying parts from becoming energized.
 
From a practical standpoint, that’s why the NEC treats the neutral as a hot wire once it leaves the service disconnect, sure the poco COULD run a separate equipment ground to the transformer, virtually eliminating the open neutral energizing anything problem, by moving the bond out there, but for practical reasons, they don’t require it, due to costs involved and a large lobbying presence.
 
Nobody answered the OP question.

To the OP. You have to have a solid understanding of the the fundamentals of electricity to grasp what your asking. Generally speaking and I do mean generally speaking, you won't be electrocuted walking on earth if a neutral is lost. You could be if you were right next to a utility transformer or a service during that scenario but you need to be very close and you would need to become a part of the path. Which could happen if you were touching something grounded with your hand and standing bare foot. The farther you get from the service or transformer the less voltage drop will occur in the earth and the safer you will be. Most of the voltage gradient is near the transformer or the services. In theory the more earth you have the better conductor it is because of the infinite parallel paths in the soil. So the bird on a wire theory comes into play. The earth really is not "energized".

This is a danger for pools and such which is why they only protection is to bond all parts and conductive surfaces in the area of the pool together. If all things are bonded then they are all equal potential and so the voltage between parts is negligible. The resistance of the bond then become critical here since any resistance will increase the potential voltage between parts and elevate the danger if a fault occurs. This is what mbrooke was referring to when he said ".2 ohms". Again bird on a wire. analogy.
 
don_resqcapt19 said:
If you open the service neutral, there will most likely be hazardous voltages on everything connected to the electrical system unless you happen to have a common metal underground water pipe as the grounding electrode...in that case you probably won't even know the that neutral is open. The other grounding electrodes cannot flow enough current to prevent all of the non current carrying parts from becoming energized.
Click to expand...
I should have read closer. I was talking about load side neutral. I agree about service neutral.
 
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