Generator Grounding

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brian john

brian john

Senior Member
Location
Leesburg, VA
I have a customer that has two generators 480/277 VAC 3 phase 4 wire that are the stand by power for a site. Both Generators have a main circuit breaker at the generator. The generators are outdoors in separate enclosures and the main service and ATS?s for this site are located 50 feet away in the building.

Generator One feeds the Normal of ATS One, Generator Two feeds the Emergency of ATS One, The Load of ATS One feeds the Emergency of ATS Two, the Normal of ATS Two is utility and the load of ATS Two is the site load.

The ATS are 4 poles, and the Main (normal utility) service is grounded per the NEC. Neither generator neutral is grounded, when connected to either generator the site is operating un-grounded.


The customer feels the generators neutrals should be bonded to the ground in the ATS?s. I feel the generator neutrals should be grounded at the generator; I referenced 250.30 (A) (1).

Any thoughts?
 
Re: Generator Grounding

Brian,

I agree with you,since the first disconnects are at the generators then that is the place for the N/G connection ,not the ATS.

frank
 
Re: Generator Grounding

Ron:

There is no doubt the installing contractor missed the boat on this one, and I realize the neutral NEEDS to be grounded. My question is the location of the neutral to ground connection.
 
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