David, I disagree with your assertion that 'If you are protecting the feeder with a 400 A breaker, the ampacity must be at least 400 A.'
Section 240.4(B) clearly states for less than 800A protective devices we are allowed to go up to the next higher standard overcurrent device rating. In this...
I'm looking for help determining the answer to the following in accordance with the NEC.
A 480v 3-phase 400A panel board with a 400A 100% rated main breaker is being installed. It is fed by a 400A 100% rated breaker in an upstream distribution board. The question is about required ampacity of...
