Bond to Metal Cabinet?

[iggy2]

We have a design for a multi-building site. There will be a utility vault with (3) indoor MV transformers. The transformers will feed (3) "transclosures" (not an accepted term...). The transclosures are merely bussed cabinets outside the vault, which will have incoming secondary conductors from the vault transformers (incoming conductors installed by the utility), and outgoing secondary conductors to the service equipment at the six buildings. (Due to the distances, there are many sets of conductors due to voltage drop, and the transclosures are a way to 'boil down' (30)+ sets of secondary conductors before they run into the vault.) The 'point-of-service' then is the load side buss of the transclosure cabinets, since the Owner is installing the load side conductors out of the cabinets and the cabinets. The incoming/outgoing circuits are 3 phase/4 wire.

Ordinarily, we would not call for a ground/bond conductor from the secondary terminals of a utility transformer to the service equipment. But in this case, since the transclosures will be metallic, I believe that 250.4(A)(4) would require that we bond the transclosure cabinet to the services at each building. This would also seem to satisfy 250,24(A)(2).

Agree? Disagree?

 

[jaggedben]

Disagree. The 'transclosure' can be bonded to the grounded conductor with an SSBJ. See 250.92.

250.24(A)(2) requires a grounding electrode at the transformer building. It is a grounding requirement, not a bonding requirement.