Remote Meter Grounding

[scotteng]

I have project with a 400A, 120/208V, 3-phase, 4-wire service served by a pad-mounted transformer. The meter is post mounted, self-contained 320A located adjacent to a pad-mounted transformer that is remote from the building. NG bond occurs in the main at the building and we are showing connection to two driven ground rods and all available grounding electrodes at the building. We are also calling for a driven ground rod and #4 Cu ground the meter per POCO requirements. The issue I have is that the AHJ have made a comment to remove the ground at the remote meter and to make all connections to ground at the main disconnect, citing 250.30(A)(7). This would effectively mean that we will install an EGC in our service lateral (never done that before) and I have question about what size that conductor would need to be. Any thoughts or comments are appreciated.

 

[hurk27]

I have project with a 400A, 120/208V, 3-phase, 4-wire service served by a pad-mounted transformer. The meter is post mounted, self-contained 320A located adjacent to a pad-mounted transformer that is remote from the building. NG bond occurs in the main at the building and we are showing connection to two driven ground rods and all available grounding electrodes at the building. We are also calling for a driven ground rod and #4 Cu ground the meter per POCO requirements. The issue I have is that the AHJ have made a comment to remove the ground at the remote meter and to make all connections to ground at the main disconnect, citing 250.30(A)(7). This would effectively mean that we will install an EGC in our service lateral (never done that before) and I have question about what size that conductor would need to be. Any thoughts or comments are appreciated.

First a meter is not a service disconnect, it is nothing but a wide point in the service entrance conductors, or latterals, if this meter is a CT type, which is most common for transformer mounted then it is under the control of the POCO.

250.142(A) clearly allows the use of the neutral (grounded conductor) ahead of the service disconnect to be used as the grounding conductor, GECs will have to also land at the service disconnect the point of the main bonding jumper. see 250.24.

I see no reason for a required EGC between the building disconnect and the pad mounted transformer, as the service grounded conductor is the EGC (250.142(A)

 

[texie]

I would agree with Hurk27. I think the AHJ is greatly mistaken here. And besides, where would you get a self containd meter can with an isolated neutral?

 

[Smart $]

Additionally...

Outdoor Transformer. Where the transformer supplying
the service is located outside the building, at least one
additional grounding connection shall be made from the
grounded service conductor to a grounding electrode, either
at the transformer or elsewhere outside the building.

 

[scotteng]

Thank you everyone. I appreciate the comments.