250.30(A)(5)

[ADub]

I'm looking for some clarification on exception 2 of 250.30(A)(5). Is this simply saying if your transformer feed comes from service equipment with a GEC connection you can use this to get a GEC to your SDS if all the conditions were met? Would you be able to pull the GEC in with the transformer primary feed? I'm wondering what a real world application of this would be because it seems like it could be a very useful exception unless I'm completely misunderstanding it. Thanks

 

[david]

i have seen service equipment at sites where the 480 volt service equipment had an SDS as part of the service equipment enclosure for 208/120 volt loads


"(2): Where a separately derived system originates in listed equipment suitable for use as service equipment"

 

[ADub]

i have seen service equipment at sites where the 480 volt service equipment had an SDS as part of the service equipment enclosure for 208/120 volt loads

I've used Square D's equipment like this, they call them Ipacs I believe. Do you think this exception is only pertained to this type of equipment?

 

[david]

I would think so since the service would be required to be bonded to the grounding electrode system or a feeder disconnect for a secondary building would be bonded to the buildings grounding electrode system