MBJ 4000A Service at Data Center

[hacim23]

Per design drawings we have left the MBJ at the MB of the switchboards and not in the XFMR. Just recently one inspector is saying that with the XFMR being outside that the MBJ is required to there in the XFMR and not inside at the first disconnecting means. I've been looking around in 250.30 and cannot find anything saying that this is a requirement. Take'er away......

 

[ron]

Who owns the transformer, the utility or the building owner.

I typically see the MBJ at the incoming main circuit breaker, and then if the utility owns the transformer, the utility will also bond at the transformer secondary.

If the building owner has a primary service and owns the transformer, we bond at the transformer and don't bring the neutral into the building (if there are no L-N loads).

 

[hacim23]

Who owns the transformer, the utility or the building owner.

Building owner

 

[ron]

If the building owner owns the transformer, then it it can be at either location.

 

[augie47]

I believe you will find the answer at 250.30(A)(1)...and note exception #2