Grounding 1000 amp SE rated ATS - GFP

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xguard

Senior Member
Location
Baton Rouge, LA
I have an existing building with a 1600 Amp Switchboard that has a ground fault sensor and an electric trip bolted contact switch. I've been tasked with connecting the building to generator power through an ATS. I planned to use a service entrance rated ATS and have it between the utility and the switch board. I have two questions about this arrangement.

One: Because of the ground fault protection I've read that I should switch the neutral. So the N and G will be bonded in the generator and in the.....this is where I'm confused. Typically I'd say in a service disconnect that's ahead of the transfer switch but in this case the service disconnect and transfer switch are combined. I would assume this is accounted for in the SE rated transfer switch but i haven't found anything definitive in various manufacturer's literature. Can any one confirm this or point me in the right direction?

Part Deaux: Some (maybe most or all) of the 1000 amp plus transfer switches I've looked at come with ground fault protection, if the transfer switch has built in ground fault protection could it interfere with the ground fault protection in the switch board? Should the switch board ground fault protection be disabled?
 

ron

Senior Member
FWIW, I've never seen an ATS with integral GFP. And I deal with a lot of them.

Is the 1600A service 3 wire or 4 wire down stream of the service disconnect? I will guess there are 4 Wire loads, hence your question.

You will want a 4 pole ATS and the gen CB will have GFP too guessing it will be 1000A, 277V and larger.

https://www.ascopower.com/globalassets/documents/asco-white-papers/ats-selection-basics-2.pdf

https://www.ascopower.com/globalass...te-papers/switching-the-neutral-conductor.pdf

https://www.csemag.com/articles/choosing-between-3-pole-and-4-pole-transfer-switches/
 

xguard

Senior Member
Location
Baton Rouge, LA
Thank you! I'm reading through them.

FWIW, I've never seen an ATS with integral GFP. And I deal with a lot of them.

Is the 1600A service 3 wire or 4 wire down stream of the service disconnect? I will guess there are 4 Wire loads, hence your question.

You will want a 4 pole ATS and the gen CB will have GFP too guessing it will be 1000A, 277V and larger.

https://www.ascopower.com/globalassets/documents/asco-white-papers/ats-selection-basics-2.pdf

https://www.ascopower.com/globalass...te-papers/switching-the-neutral-conductor.pdf

https://www.csemag.com/articles/choosing-between-3-pole-and-4-pole-transfer-switches/
 
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