ECN Forum Forums Code Related Discussion NEC & other Code issues Large Generator Grounding 480/277 V

Looking at the code you get to 250.20 that talks about how you ground a SDS connected generator. If it is a non - SDS (unswitched neutral), there are no grounding requirements beyond the 250-122 EGC from the attached service.

From the handbook
Non SDS



SDS



If you do have an SDS it takes you to 250.30 that points you to 250.66 for the details of the GEC 250.52 for the electrode etc.