10 amps on water pipe

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Fordean

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Water pipe. Which is also a 1st Grounding Electrode, in conjunction with the 2nd Electrode- Ground Rod,


Their is 10 amps on the Water pipes when clamped with microwave and toaster oven on. Any comments. Never seen so high a value.

This is a 120/240v 1 ph
 
don_resqcapt19

don_resqcapt19

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Is the water pipe grounding electrode part of a metal underground water pipe system that serves other buildings in the area?

If that is the case, I would suspect a problem with the service neutral.

Note that in the case of a common metal underground water piping system, it is not uncommon to see 15-20% of the neutral current on the water pipe.
 
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GoldDigger

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don_resqcapt19 said:
Is the water pipe grounding electrode part of a metal underground water pipe system that serves other buildings in the area?

If that is the case, I would suspect a problem with the service neutral.

Note that in the case of a common metal underground water piping system, it is not uncommon to see 15-20% of the neutral current on the water pipe.
Click to expand...

And if the current is there even with your main open it is somebody elses neutral that is compromised. :)
 
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GoldDigger

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Fordean said:
Amp are there when Breaker is out.
Click to expand...

Most likely explanation:
There is at least one other house on the same POCO transformer secondary as the one you are working on.
That house has a high enough resistance neutral that a lot of its unbalanced neutral current is going from their house side neutral through their water pipe GES bond to the water pipe, to your house and its water pipe, to your water pipe neutral bond, and from there into your POCO neutral to get back to the transformer secondary.
 
don_resqcapt19

don_resqcapt19

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Fordean said:
Amp are there when Breaker is out.
Click to expand...
Something is not right.

If the current on the water pipe is going up when you add local loads (especially where it is going up that much for the load you added), that tends to indicate that the service neutral for that house is compromised.

If the current is still there with the local main off, that tends to indicate that the service neutral for your building is ok, but the one to an adjacent building is compromised. The grounded conductor current path is from the other building neutral>main bonding jumper>GEC>water pipe>GEC at your building>your main bonding jumper>your service neutral>utility transformer.

To be sure we need the currents on the supply conductors, both grounded and ungrounded as well as on the water pipe.
 
gadfly56

gadfly56

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don_resqcapt19 said:
Something is not right.

If the current on the water pipe is going up when you add local loads (especially where it is going up that much for the load you added), that tends to indicate that the service neutral for that house is compromised.

If the current is still there with the local main off, that tends to indicate that the service neutral for your building is ok, but the one to an adjacent building is compromised. The grounded conductor current path is from the other building neutral>main bonding jumper>GEC>water pipe>GEC at your building>your main bonding jumper>your service neutral>utility transformer.

To be sure we need the currents on the supply conductors, both grounded and ungrounded as well as on the water pipe.
Click to expand...

I wonder if this might be a case of double failure? Local neutral is bad and an adjacent one as well?
 
don_resqcapt19

don_resqcapt19

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gadfly56 said:
I wonder if this might be a case of double failure? Local neutral is bad and an adjacent one as well?
Click to expand...
If the service neutral is bad at the house with the current on the water pipe while the main breaker is off, where is that current going?
 
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GoldDigger

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ptonsparky said:
Well, it is going down the street to the next house.:)
Click to expand...
In that case it would just be current on the water pipe, not current on the EGC. :angel:

If the current on the POCO neutral with the main open is equal and opposite to the current on the water pipe GEC it is pretty conclusive that it is coming from somewhere else and using your POCO neutral.

Much less likely is that it is coming down the POCO neutral from a point which is common to several drops but has become disconnected from the transformer neutral and is headed out the water pipe to get to the POCO secondary winding's ground.
 
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