MAIN BREAKER

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Abe5gt

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Hi.
I have some electrical drawings that has a MCC with 3 control panel with a 150A breaker, 50A, 20A and a hoist with a breaker of 20A all individually connected to the same bar (sum of 240). The main breaker of the MCC is 400A. Can I lower the main breaker capacity to 250A? Is there a formula or a NEC table I should go by?
 
The basic requirement is that the panel (in this case the MCC) must be protected against overcurrent by a device that has a trip setting no higher than the rating of the panel itself. So long as the MCC is rated for 400 amps, you can use a main breaker that is any value that is 400 amps or lower. So, yes, you can use a 250 amp main breaker. But I repeat the earlier question: why should you want to?
 
What's so funny about this question (funny strange, not funny ha ha) is that I was kind of having this conversation earlier today.

He want's to do it but doesn't need to, but could you imagine the uproar if an inspector asked him to do it.:huh:
 
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