Sizing of Feeder Circuit with Interlocked Loads

[7JLAman4]

I'm looking for NEC requirements for sizing of feeder circuits that supply panel loads that are interlocked and not permitted to operate concurrently. Not sure if I have seen this requirement previously, but currently looking for a reference to allow "derating" of the required feeder circuit protection if the certain branch circuits are interlocked preventing certain branch circuits from operating concurrently.

 

[rbulsara]

Except for loads for dwelling units (residential) NEC does not have prescribed method as to how to come up with your load calcualtions.

For other systems it is up to the designer to determine continouos and non-continous load on a feeder, based on the knowledge of the load system. NEC in fact does not care if you undersize or oversize the feeder, it is only interested in that whatever conductor/overcurrent device combinaiton you pick meets the code.

So there is no so called 'derating' of a feeder to interlocked load, you just take larger of the interlocked loads as the load for feeder sizing.