Portable Generator Grounding

[Roger Nobles]

I'm on a USACE construction site.
We have a Portable Generator that is bonded with a ground rod.
The Generator is dedicated power for a hard-wired temporary A/C system that sits outside with only ducts entering into the building, and a hard-wired piece of flooring equipment that is inside the building. No cord and plug tools or lighting are connected to this Generator.
The Building Temporary power is on the opposite corner of the building.
The Portable Generator is 277/480V and the Building Temporary is 120/208V.

Does NEC 250-58 apply?
Do the two systems need to be bonded together?

 

[RUWired]

I would say that 250.58 does apply since 250.34 requires that generators be connected to a grounding electrode if not connected by cord and plug.

 

[Danfrey]

Question about seperately derived systems

Question about seperately derived systems

In the case listed above, would the generator be considered a seperately derived system? If so, wouldn't 250.30 (A)(4) make the common grounding electrode "permissible"?

 

[RUWired]

I would say the gen set is a SDS because its a stand alone without any mention of a transfer switch being involved.

250.30(A)4 pertains to multiple SDS's using a common GEC. With the OP, he has only one SDS.

Rick