amperage on grounding conductor

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ptrgator

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I upgraded the service to a house and installed a meter/panel combo at the service entrance, ran 4 wires to the original main panel in the basement which became a subpanel, split the grounds and neutrals in the new subpanel, bonded to the water and gas from the main and while tying in the grounding conductor in the subpanel, I noticed arcing as it came close to the terminal. I put an amp clamp on it and found current fluctuating around 2 amps. It changed as I turned off different 120 volt breakers. Then I turned off the power at the main and subpanel and found the amperage to be around 1 amp. I read another posting about current on the GEC relating to a poor nuetral at another house that's also bonded to the water line. Could this be what I have going on and should I be concerned about the current changing as different 120 volt loads come on and off?
 

don_resqcapt19

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Location
Illinois
question is where do I go from here? Should I be concerned?
No. In areas with common metal underground water pipe systems it is not unusal to have 20% or more of the grounded conductor current flowing on the water pipe. The water pipe is in parallel with the utility grounded conductor as a result of the code required connection of the grounded conductor to the water pipe at each house.
Don
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
why is the amperage on the ground effected as different loads come on and off
Because 120 volt loads change the grounded conductor current and the water pipe is in paralle with the grounded conductor.
I should have told you to check the current on the service grounded conductor before I told you that the current on the water pipe is no problem. If there is little or no current on the grounded conductor and you have more current on the water pipe, then there is a problem with the service grounded conductor.
Don
 
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