current on the water pipe GEC

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ibew501ed said:
I believe he means current leaving your house on the water pipe seeking its source in parallel with your neutral (groundED conductor) OR current entering your house ( from your neighbors house that lost their neutral) seeking ITS source via your neutral connection to the poco transformer
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LOL, now that you explain it, all I have to say about me is DUH!

Thanks,
 
I believe the situation is caused from a ground loop between the residence's load center and the POCO transformer. I don't know very much about the POCO side of things, but I have been lead to believe that at least with my POCO, they bond the transformer to ensure it doesn't float to a high voltage. The result is a parallel neutral path, with the second path being through earth ground.

I was having a lengthy discussion with my local inspector about bonding at a separate building, and this topic came up in the process. He is the one that told me it was standard practice for the transformers to be bonded. Is that correct?
 
Rick Christopherson said:
I believe the situation is caused from a ground loop between the residence's load center and the POCO transformer. I don't know very much about the POCO side of things, but I have been lead to believe that at least with my POCO, they bond the transformer to ensure it doesn't float to a high voltage. The result is a parallel neutral path, with the second path being through earth ground.

I was having a lengthy discussion with my local inspector about bonding at a separate building, and this topic came up in the process. He is the one that told me it was standard practice for the transformers to be bonded. Is that correct?
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the poco here grounds the neutral at the transformer and we ground it at the building.

they feed the transformer with a 3 wire wye and connect the sheath of the MV cable to XO of the transformer, thats where we connect the neutral. that sheath also connects to ground rods that we drive and cadweld.

they also ground there sheath at the pole where it hits the cutouts
 
Rick Christopherson said:
That's what I thought, so yes, it is a ground loop between the transformer and the load center. The lower the resistivity of the soil, the higher the current division.
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Rick: I have investigated numerous issues as discussed in this post NONE have to do with soil conditions at 120 VAC it just does not seem to be an issue*1. In addition we do ground testing in this area 5 ohms and less is the norm. The issue is typically common water pipe/common transformer. Or down stream grounds on the neutral (more often commercial structures.)


* I say this as when we isolated the system water pipe the ground current issue was resolved.
 
brian john said:
Rick: I have investigated numerous issues as discussed in this post NONE have to do with soil conditions at 120 VAC it just does not seem to be an issue*1. In addition we do ground testing in this area 5 ohms and less is the norm. The issue is typically common water pipe/common transformer. Or down stream grounds on the neutral (more often commercial structures.)


* I say this as when we isolated the system water pipe the ground current issue was resolved.
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i tested the ground rod i installed for my generator and its about 100 ohms. i dont know how to test my waterpipe GEC with the 3 point fop tester i have. usually 100 ohms for the rod is the norm here i believe
 
hardworkingstiff said:
Direction? We're talking AC right? I don't understand the direction remark, can you elaborate?
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Yes the current will always try to return to the source and if your connection is better than your neighbors it will try to return to the source through your service. Very dangerous imo yet happens every day unoticed.
 
quogueelectric said:
Yes the current will always try to return to the source and if your connection is better than your neighbors it will try to return to the source through your service. Very dangerous imo yet happens every day unoticed.
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There may be many houses connected to a single transformer and there is the source. Not all paths will be as planned.
 
ibew501ed said:
Does this situation indicate that when a plumber cuts the incomming water main for a repair he would ALWAYS or rarely be exposed to enough current to cause a big problem?
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No. The only safety issue for the plumber is when there is a problem with the grounded conductor. Even when the water pipe is carrying current, as long as the grounded conductor is in good shape, the only voltage available to provide a shock is the voltage drop on the grounded conductor itself. This will not be a shock hazard.
 
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