Ground fault protection

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cppoly

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For 1000 amps 277/480V, what does the exception to ground fault protection of equipment mean:
It's not required if GFPE is provided on the supply side of the feeder and on the load side of the transformer?
 
That if there is GFP upstream that can "see" a downstream ground fault, then you don't need to protect the feeder again with separate GFP.

An example where this gets messy is if there is GFP on the service and a feeder is derived from a downstream delta-wye transformer (SDS) then the feeder on the transformer secondary is not protected upstream so you need it again if you are above the 1000A and 277V to ground.
 
ron said:
That if there is GFP upstream that can "see" a downstream ground fault, then you don't need to protect the feeder again with separate GFP.

An example where this gets messy is if there is GFP on the service and a feeder is derived from a downstream delta-wye transformer (SDS) then the feeder on the transformer secondary is not protected upstream so you need it again if you are above the 1000A and 277V to ground.
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That makes sense. But, if it was on the service then the service would be 277/480V and if there's a transformer then I'm assuming step down to 120/208V, why would you need GFP again?

Or would that situation happen if the GFP on the service was voluntary for a 120/208V and there was a step up to 277/480V so that's where that situation would apply that you mentioned?
 
The exception would likely be used where there is a feeder to a separate building. The feeder switch might have GF protection which means the disconnect at the second building would not need to. Another situation would be with a 480-480Y/277 isolation transformer.
 
This also covers a situation such as a 1000 amp service main (which needs GFPE), then say, a single 100 ft, 1000 amp feeder to a panel. 215.10 Excep. 2 is saying you don't need it again.
 
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