Wire Size with 100% Breaker

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MME-elec

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Is there anything that allows wire sizing to be based on 100% rated OCP instead of 125% continuous + 100% noncontinuous load?

A potential continuous load of 541 amps may be protected by 100% rated breaker.
541 amps x 1.25 = 676 amps seems to require 2 sets of 500mcm. I am told that since a 100% rated breaker can protect 2 sets of 350mcm (620A ampacity), I can ignore the 1.25 factor. Can anyone quote NEC paragraph for such allowance?

(all conductors copper, 75 degree C ratings, 80 degree ambient conditions)
 
Per 215.2(A)(1) Exception No. 1 if your overcurrent device protecting the feeders is rated for 100% operation then the allowable ampacity in your conductors would be 100% of your load. So in your case you could run (2) sets of 350 KCMIL conductors to your 600A Overcurrent Device.
 
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