Ground Loop

[Ravenvalor]

Hello,

I looked at a residential service last week that had the meter base about 25' from the service panel in the basement. It was feeding the service panel with 3 - 4/0 aluminum conductors in 2" pvc run on the outside of the home. it had a ground rod at the meterbase and a ground rod at the service panel. A number 6 solid copper conductor was running from the service panel, to the first ground rod then to the next ground rod and then to the meterbase. Considering that there is already a 4/0 conductor connecting the meter base to the service panel would one consider this a ground loop? If so is it a code violation or possibly a hazard?

Thank you,

 

[PetrosA]

I think it's the utility that determines whether or not the GEC gets connected to a meter base or not rather than the NEC, but I've personally never seen a setup like that.

 

[Smart $]

IMO, the term ground loop does not exist and has no meaning in power wiring. That said, what you do have there is a parallel neutral current pathway... but at present there is no provision specifically prohibiings such on the supply side of the service disconnecting means.

 

[Ravenvalor]

Thank you.

Thank you.

I will definitely touch base with the AHJ.
Thanks for the help.

 

[electricalist]

If a meter enclosure is connected to a service panel via a metel raceway, with sec in it, you would have the same thing. Although in your case when the copper thieves steal the rod to rod piece itll be ok

 

[Ravenvalor]

If a meter enclosure is connected to a service panel via a metel raceway, with sec in it, you would have the same thing. Although in your case when the copper thieves steal the rod to rod piece itll be ok

Good point there. I guess since in my case it looks like a wider loop maybe there is a greater potential for problems. Maybe in your example there is a cancellation effect?

I plan to talk with an inspector today and let you know what his thoughts are about it.

 

[Ravenvalor]

I spoke with the local inspector about the ground loop and he said that he does not pass that type of set up because of the double neutral effect. I always thought that the ground loop caused more potential damage than just the double neutral effect like when a surge struck some type of electrical magnetic loop would create heat or something but that's just my imagination.
Ground loops are only equated with double neutrals which can cause a fire if the main neutral is lost and the #6 solid copper tries to carry the neutral load.
Thanks for the help with this.

 

[electricalist]

i have seen lets say 3 emts pipes leave a panel via drilled holes and go to a 12x12 with drilled holes then had bonding bushings on all 3 going to a ground bar kit where the paint was sanded, holes taped ,lock washers and nuts on the back and a ground in each conduit going to the ground bar and then leaving,,,al from a 120 -208 panel but all 120v circuits,,,im my mind it seems like way too many paths to save my life,but i dont know how it travels.