New Generator ATS Service Whole Building

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greekdaddy

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I have a building that is fed from a transformer 300 feet away. Service conductors are 7 sets of four 600kcmil cable. 3 phases and neutral in each conduit.

The building is fed 480/277 from these conductors.

I am looking into a new ATS and GENERATOR that will be located 300 feet away near the transformer (this is done for space and aesthetic reasons).

Is there a way I can configure a non-separately derived system (3 pole, 4 wire ATS) to feed my building, not have figure out how to stuff an EGC in existing seven conduits and maintain the NEUT-GND bond in the building.

The bigger challenge is that the ATS has a 2500 AMP breakers that requires ground fault protection. Is there any way I can maintain this protection and keep bond in the building?

Also, does the requirement for ground fault protection allow me to monitor for faults at the building and shunt trip the feeder breaker?

Any help would be appreciated.

Parts of the code I have been tackling with are:

230.82(5) <-- allow ATS to be upstream and still consider my building to be "service disconnect"
250.142(A)(1) <- allow me to bond at building
250.122(F)(2) <- possibly try running 2/0 instead of 350kcmil

THANKS FOR ANY HELP YOU CAN PROVIDE!!!!
 
A couple of points to consider:

1) Does the design of the proposed generator even allow it's neutral be isolated from the generator ground? (you'll need that for a non-SDS installation)

2) Does the ATS design allow the neutral to not switch ? (i.e. only the "lines" are switched) Your description sounds like it does.

If you can answer yes to both of these questions, you likely could install as non-SDS system and be able to continue using your existing service neutral-to-ground bond.

Refer to 250.20(D) FPN 1 and 2.
 
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Greekdaddy:

If you are going to locate your ATS at the transformer I am assuming that it is to be suitable for use as service equipment and will be provided with a service disconnecting means than includes GFPE protection. This will prevent you from having any neutral to ground bonds on the load side of this point (250.32(B)).
 
I am thinking along the lines of RB1.

It's going to have to be a service rated switch and will have to be bonded at that point.

Electrically it will be much easer to locate the switch at the building it serves.
 
Let me see if I understand this correctly. You want to interrupt the 2500A Service feeder near the utility transformer by inserting a 2500A SER transfer switch. Correct? If so, then the only operational issue I see would be if your existing service entrance has mulitple switches with no GFCI on them. Your GFCI on your new 2500A main in the transfer switch will not be able to distinguish between normal current flow and current flow in the grounding system since the neutral-to-ground bond is downstream.
 
Ram, a SR - ATS in this size and voltage will have to contain GFP protection.

Once you add GFP protection you must run separate neutral and grounding conductors from that point forward.
 
Precisely. That is why 250.32(B) list item No. 3 prohibits using the grounded circuit conductor for grounding equipment in a building or structure that is served by a feeder when GFPE protection is installed on the supply side of the feeder.
 
iwire said:
a SR - ATS in this size and voltage will have to contain GFP protection.

Once you add GFP protection you must run separate neutral and grounding conductors from that point forward.
Click to expand...
Given this fact -- which I hadn't considered -- this will have to be an SDS system then, with a switched-neutral ATS ... right?
 
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