480VAC MCC

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aholm

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We have a 480VAC MCC with a 1200A incoming circuit breaker with a shunt trip. The horizontal bus bars are rated 1200A. We would like to connect a 60A/3phase circuit breaker (also mounted in the MCC) parallel to the incoming in order to still have some control power available in case the main is tripped out. What does the NEC state regarding cable size to the smaller breaker?
 
Re: 480VAC MCC

A conductor is protected at its rated ampacity.
Will this be a service disconnect in addition to the shut trip?
What is the available fault current?
 
Re: 480VAC MCC

Yes, it is in addition to the shunt trip. Connected to the incoming feed before the 1200 breaker.
The fault current is 42kA.
 
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