This is a head scratcher

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RAM460

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Please bear with me, We came across a interesting thing today.
We were finishing up some loose ends on a house remodel. The service was upgraded - new weatherhead, riser, outdoor meter can, service entrance into the new 150 amp Sq D panel. New ground rod, and wire, new bonding wire to the street side of water meter. The house has a copper water main from the street, and plastic lines through out. Upon taking off the the wire from the water pipe clamp (so it could be rerouted), there was a big blue arc.
It acted like the was a open neutral. Upon reading across it we were getting 50 - 60 volts between the water pipe and the bonding wire. You would think that with the neutral and the bonding screw in the panel along with the ground rod all connected, we would not be getting any voltage on that wire. We found out that the lights in the basement would dim when the wire was removed. After checking and tracing all that circuit, and made sure the neutral was connected all the way through, we had that same results..

It is impossible to describe everything we tested and checked, however 2 electricians 1 with 20 yrs in trade and one with 26 yrs in trade we are totally baffled.. I will keep checking this and updating as suggestions are made, if it something we has already checked for.

I want to thank you all in advance for you help...
Roger
 
Thank You
We did check voltage between phase to phase (238 volts) and both phases to neutral (117 - 118 volts) with both grounding and bonding wire disconnected.

We had thought that the POCO may have been working on the lines in the neighborhood, we have not been able to confirm that either way.

We were thinking of disconecting the neutral from the panel, hook up the ground rod and see if we were still getting voltage off the bonding wire to the water service.
 
Possibilities:
1. The POCO neutral is not secure/connected. Current is taking an alternate path to XFMR thru water main to someone else panel then to the POCO XFMR. When the GEC is disconnected, do you still get ~120 VAC to neutral?
2. The water main is energized and your providing the path to the POCO XFMR via your GEC. To test of this is the case, if you opened the main breaker (that you just put in), and you still get power to flow thru attachment of the GEC to the water main then the power could be from the water main. (And come to think of it, detach the ground rod connection before you do this).
3. Others I am sure exist.
 
At first read, I suspect that the PoCo side of the service neutral is open. I suspect that your 150 Amp service unbalance load is being forced to return to the PoCo transformer out through the water pipes, to the neighbor(s) GEC and through the neighbor(s) service neutral to the transformer.

Leave the GEC connected to the water pipe for now and, as Kessler suggested, get the PoCo out there with the knowledge of your having done the good work and trouble shooting that you've already done.
 
You mentioned that the basement lights dim when you remove the ground wire. Does the same thing happen to other circuits, or just the basement lights? Have you tried shutting off the circuit for the basement lights and seeing if the problem disappears?

I also suspect the neutral is open on the PoCo side. Have you taken readings at the panel with variable imbalanced loads? I've seen situations where everything seemed OK with the voltage P-P and P-N until loads were applied. Then the voltages got imbalanced. If that's the case, then I'd say Al's right. Actually, Al's usually right. :D
 
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What was the voltages at the main, with main off, and then what was the voltages at the main with load on?

How much current was flowing in the water pipe?


A guess would be a bad connection at the POCO nuet feeding the home...
 
RAM460 said:
We did check voltage between phase to phase (238 volts) and both phases to neutral (117 - 118 volts) with both grounding and bonding wire disconnected.
Click to expand...
Was this also with the service disco off?

If the disco was off, a high impedance open of the neutral, somewhere between the 150 A panel and the transformer will allow a voltmeter to make what looks like a normal voltage reading.

Putting the neutral under load, with the GEC / MBJ / ground rod disconnected is a formula for voltage swings in the branch circuits in the house that may well damage your clients electronics and other UE.
 
If it was an open neutral the lights in the basement should have gotten brighter.. Are you sure there's not a drywall screw or nail stuck in your romex some where? Are the basement lights flouresent?
 
I can tell tomorrow will be fun, back to this...

It seems as though the problem occurs will a lighting load connected, or even when a dehumidifer was plugged in. It didn't matter which circuit it was as long as there was a load on it.. The house is vacant so no worry of damaging electronics or other equipment. We had all other breakers off in the panel except for the basement lights, cause that was the easiest to see. we disconnected the wiring on that same circuit that went upstairs and fed other lights. We had thought at one point there was a set of 3 ways, we thought that maybe they had switched neutrals some how backfeeding the power back down to the our GEC.
We did check power with GEC disconnected, and we were getting 118 volts phase to neutral.

Has anyone ever gotten a voltage reading ( almost 100 volts) between either phase and a #2 wire GEC that was disconnected at both ends? Approx 12 ft. long ( just a piece of wire)

How about a voltage reading (50 volts) between either phase and a guy standing on a plastic 5 gallon bucket in rubber sole sneakers?

How about a voltage reading ( 60 volts) between either phase and the wodden floor joist? Never heard of that EVER

This house has some sort of Gremlins

Roger
 
Roger
It sounds like either of two scenarios.
1. The neutral is not sufficient enough at the building you are in.

2. A neighbor has lost their neutral and your building is the neutral path back to the source.

Are you testing with a digital tester or a wiggy type tester?
 
Yes, Pierre,

A Wiggy would be good. Any kind of voltmeter with a d'Arsonvol movement, that is, a wire wound armature that moves a needle. . .or a wire wound solenoid like a Wiggy.

Digital meters can have such unbelievably high input impedances that they will measure the voltage to a floating GEC 12' long. They're easier to use, but they give some readings that have to be ignored. . .that's the hard part.

Given your last description RAM460, I agree with Pierre also, that the neighbor(s) unbalance is coming through. . . You can verify that with the meter pulled and an amprobe on the PoCo neutral at the location that the PoCo lateral or drop attaches. . .
 
I have a quick suggection: try the basement-light experiment again, but with the breaker feeding the kights on the opposite phase.

Now see whether opening the connection again dims the light, or if it instead gets brighter.

If the former, the house neutral is broken somewhere; if the latter, there's voltage on the pipe, and the problem is originating in another house.


Note: I could be totally off here, but it's late. :eek:
 
I have never seen the "other house" senerio, but that does sound plausable to me. That would also be very interesting.

Someone said something about maybe the water pipe ibeing hot. Are the utilities fed underground?
 
I first want to thank everyone who replied to my question.

We went back there today a couple more tests and we called the POCO.
Come to find out once they got there, we had already pulled the meter, they tested phase to phase and phase to neutral, they started to say everyting was normal. I told them with no load it did read normal. The POCO got what they called "The Super Beast" Its a load test that plugs in where the meter goes, they knew instantly there was a bad neutral.
They traced out their overhead and found a broken neutral in a line that only fed the house we were working on and the vacant house next store that has no power.
I guess if there is a lesson to take from this its:
" Go with your first gut instinct" We both said just like most of you in here said " it seemed like an open neutral ".

Thank You All Again

Roger
 
Try putting an amprobe on it while under a load. If your neutral isnt carrying the unbalanced load, it would seem fairly evident that your incoming nuet is insufficient, and the water pipe may be carrying it.
 
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