2v on grounding conductor at water meter

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topend

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I was called to check the grounding conductor when a plumber started to remove the ground clamp at the water main, so he could replace the main shut-off valve, and noticed some arcing. I removed the grounding conductor (there was indeed arcing), and discovered there was less than 2v on the grounding conductor. Is this a hazardous situation?
Also, the customer says his lights are now flickering, and has had two lamps and two surge suppressors die since I left.
HELP!
Thanks in advance.
 
Some arcing is normal, as is 2v, which is actually relatively low. I would have measured the current.

Who is responsible for the ground wire being removed? If it arced for the plumber first, it's his baby.

If everything has been replaced, then there were issued before. I would not accept the blame at all.

Flickering lights and failing lights and surge devices should not happen on a 2v voltage imbalance.
 
If the removal suddenly caused problems in the house you might have a bad neutral on the line side of the panel. The water pipe was carrying the neutral current and now that pathway is no longer there. I would reconnect it immediately and then look for the problem.
 
LarryFine said:
Some arcing is normal, as is 2v, which is actually relatively low. I would have measured the current.

Who is responsible for the ground wire being removed? If it arced for the plumber first, it's his baby.

If everything has been replaced, then there were issued before. I would not accept the blame at all.

Flickering lights and failing lights and surge devices should not happen on a 2v voltage imbalance.
Click to expand...

Thanks for your response.
I didn't think to measure current. I would think it should measure very close to zero.
I subcontract to this plumbing company. Their plumber tried to remove the ground clamp, and immediately backed off when he noticed the arcing.
Nobody is pointing fingers, just trying to resolve the electrical issues. Although, it doesn't sound like anything out of the ordinary, electrically. The surge suppressors failing is a head-scratcher, though.
 
You can try seeing whether the voltage is coming from this house or a neighbor by turning off the power while measuring.
 
You don't get arcing with close to zero current.

With common underground water piping, it is very common for the water pipe to act as a parallel path for neutral current. Even with a perfect neutral you will see current on the water pipe in this situation.

If the service neutral is faulty, then most or all of the neutral current can flow on the water pipe, essentially masking the problem of the faulty neutral. Open the water pipe bond and you suddenly see the problem.

When you have an open neutral you can see excessive phase-neutral voltages on the service, which will blow out surge suppressors.

-Jon
 
LarryFine said:
Some arcing is normal, as is 2v, which is actually relatively low. I would have measured the current.

Who is responsible for the ground wire being removed? If it arced for the plumber first, it's his baby.

If everything has been replaced, then there were issued before. I would not accept the blame at all.

Flickering lights and failing lights and surge devices should not happen on a 2v voltage imbalance.
Click to expand...
winnie said:
You don't get arcing with close to zero current.

With common underground water piping, it is very common for the water pipe to act as a parallel path for neutral current. Even with a perfect neutral you will see current on the water pipe in this situation.

If the service neutral is faulty, then most or all of the neutral current can flow on the water pipe, essentially masking the problem of the faulty neutral. Open the water pipe bond and you suddenly see the problem.

When you have an open neutral you can see excessive phase-neutral voltages on the service, which will blow out surge suppressors.

-Jon
[/QUO
Thanks.
Click to expand...
winnie said:
You don't get arcing with close to zero current.

With common underground water piping, it is very common for the water pipe to act as a parallel path for neutral current. Even with a perfect neutral you will see current on the water pipe in this situation.

If the service neutral is faulty, then most or all of the neutral current can flow on the water pipe, essentially masking the problem of the faulty neutral. Open the water pipe bond and you suddenly see the problem.

When you have an open neutral you can see excessive phase-neutral voltages on the service, which will blow out surge suppressors.

-Jon
Click to expand...

Hmmm....
What is acceptable current?
Thank you.
 
However, since the arcing was potentially a symptom of a compromised neutral, with damaging line to neutral voltages with the grounding clamp removed, I do not have a large problem with the plumber calling for an electrician rather than just proceeding.
Without knowing the voltage, the plumber is also justified in considering it a possibly dangerous situation for him.
 
Tune into mike holt live for discussion on Tuesday evening 7:00 EDT, had a very interesting discussion on just this topic this past week, supposed to continue this coming week, past discussions can be viewed by going to his site https://www.mikeholt.com/live or register to watch live.
 
GoldDigger said:
However, since the arcing was potentially a symptom of a compromised neutral, with damaging line to neutral voltages with the grounding clamp removed, I do not have a large problem with the plumber calling for an electrician rather than just proceeding.
Without knowing the voltage, the plumber is also justified in considering it a possibly dangerous situation for him.
Click to expand...
I agree. If he does this regularly, he's seen and disconnected grounding electrodes before.

To take that farther, technically, the plumber should have called an electrician right away.

If "the spark" caused any damage, the plumber caused the first one, and is therefor liable.
 
topend said:
Hmmm....
What is acceptable current?
Thank you.
Click to expand...
With a common metal underground water pipe there may be 20% or more of the neutral current on the water pipe.

In the storm we had recently, a service drop was pulled off the house and the ungrounded conductors remained connected, but the neutral broke. Everything in the house worked just fine with no high or low voltages like you would expect with an open neutral. Up until a few years ago our city plumbing code required copper water service lines, and all of the mains in this area are old cast iron.
 
Years ago we had a plumber jump in a hole to cut a metallic water line. Corded Sawzall with an intact EG all the way back. Unheard of. The teeth on the blade burnt off upon contact with the pipe. No plumber in sight when we got there and none came back until things were fixed. Water line was the neutral return and the EG was even a better return path.
 
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