Requirements for disconnect between ATS and Trafo.

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masonc

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I was involved in a generator installation where the electrical contractor had installed a 1600A ATS next to a 1000KVA utility transformer, in the same room. Line voltage was 480V. The ATS was connected to the Trafo with 4x600MCM conductors per phase. There was no disconnect or overcurrent protection between the equipment and the ATS does not have a service disconnect in it.
Contractor tells me Article 721 allows this. I am worried that 1) there is no protection for the ATS in the event it closes onto a fault current, and 2) there is no way to test the ATS works, 3) no way to do maintenance on the ATS. Am I being too cautious, is the contractor correct?
 
augie47

augie47

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You didn't hear a snicker as you walked away did you ?:D
Art 721 ???
Ask him to show you that Article. If he does he has a different NEC that I have seen.
I know of NO provision that would allow an non service rated ATS to be connected directly to the utility service point.y
 
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GoldDigger

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And even a service rated ATS without a separate disconnect would require any electrician to have the meter pulled before working on the ATS.
 
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masonc

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I thought I did. There is a trafo, the ATS in the room, then 100ft feeders to main panel.

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texie

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masonc said:
I was involved in a generator installation where the electrical contractor had installed a 1600A ATS next to a 1000KVA utility transformer, in the same room. Line voltage was 480V. The ATS was connected to the Trafo with 4x600MCM conductors per phase. There was no disconnect or overcurrent protection between the equipment and the ATS does not have a service disconnect in it.
Contractor tells me Article 721 allows this. I am worried that 1) there is no protection for the ATS in the event it closes onto a fault current, and 2) there is no way to test the ATS works, 3) no way to do maintenance on the ATS. Am I being too cautious, is the contractor correct?
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Either your contractor/electrician is wildly incompetent or there is more to this story.
I've never heard of a POCO transformer installed inside a premises unless it is an open type and in a transformer vault controlled by them. And they would never allow foreign equipment to be installed in there.
In any event, if what you are saying is accurate there are a number of serious code violations. The only thing that sounds right is the conductor sizing.
Can you give us more details?
 
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