Legally required generator

[PAW2006]

I have a 100Kw generator located outside a building. It feeds a emergency lighting panel through an ATS. It is wired with 4 #1 and a #6 gnd.
Question, Does the generator have to have a Grounding electrode rod driven next to it or can the #6 grounding conductor be used back to the ATS and on to the lighting panel.
I've been through the FAQs and can't find an exact match for my situation. I've read NEC 250.30 and am confused.
Thanks

 

[pete m.]

Check the definition of Separately Derived System (in other words your transfer switch arrangement will determine whether it is or not. i.e. does the ATS switch the neutral) If it is an SDS see 250.30. If it is not an SDS the conductors from the generator are simply feeders. Also the manufacturer of the generator may require a ground rod.

Pete

 

[PAW2006]

Pete
The ATS is a 4 wire and is switching the neutral so I can ground per 250.30
From 250.30 (A) (3) I need to attach the GEC to the neutral at the same location as the bonding conductor.
But regarding the Grounding electrode there is nowhere to drive a rod so I think per 250.30 (A) (7) I can use either the building steel or the metal water pipe.
Does this sound right to you?
Does the GEC have to be 4/0?
Thanks

 

[pete m.]

Per 250.30(A)(7) you are required to use either the water or steel. In absense of both of these (which may be the case dependent on the location of the generator) you are permitted to utilize any other electrode in 250.52(A). Also take a read on the informational notes after 250.30(A)(4)

Your GEC will be sized based upon either job specifications or 250.66. The only way I know you would ever need a 4/0 would be from job specs.

Pete