215.10 NEC

[binwork91]

Question: 480V/277Y system, If my 4000A service switch has ground fault protection, do i need any ground fault protection at down stream 1200A switch?



2008 NEC


215.10 Ground-Fault Protection of Equipment. Each
feeder disconnect rated 1000 amperes or more and installed
on solidly grounded wye electrical systems of more than
150 volts to ground, but not exceeding 600 volts phase-tophase,
shall be provided with ground-fault protection of
equipment in accordance with the provisions of 230.95.
FPN: For buildings that contain health care occupancies,
see the requirements of 517.17.
Exception No. 1: The provisions of this section shall not
apply to a disconnecting means for a continuous industrial
process where a nonorderly shutdown will introduce additional
or increased hazards.
Exception No. 2: The provisions of this section shall not
apply if ground-fault protection of equipment is provided on
the supply side of the feeder and on the load side of any
transformer supplying the feeder.

 

[augie47]

Not required but might be desirable for selective coordination.

 

[texie]

Not required but might be desirable for selective coordination.

I agree. I've seen this so often over the years and it almost always, at some point, ends with an unhappy customer. I think if an engineer wants to use single level GPF he owes it to his client to make sure they understand the ramifications of doing so. In many cases just one total system black out due to single level GFP would probably pay for the extra cost of multilevel GFP.