As we all are a little unclear on areas of the trade, I have always been unclear about certain times to derate. Can someone explain to me in a simple way, with code references, when to derate. I shouldn't sya I am totally lost on when and how to derate, but when I see 400 amp switches fused at 400Amps with 400A rated wire. Where is the derating in that? This has been one of the thinhgs I never can grasp. Probably because I have never really asked for clarification.
