Multiple circuits off of the same breaker

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mull982

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Is it legal to serve multiple circuits off of one circuit breaker. For instance if I have a 400A breaker can I have one set of 500's going to panel A and another set of 500's going to panel B from the 400A breaker? Is there a max # of circuits that can be served?
 
There are three rules that come into play here. One has to do with the maximum load you can put through a conductor. Another has to do with the selection of a breaker, based on the load. The third has to do with the connection of more than one conductor to a breaker. As long as the total load through any one of the 500 MCM conductors does not exceed 380, and the total calculated load on the breaker (100% of the non-continuous plus 125% of the continuous) does not exceed 400 amps, you will pass the first two tests. But I can't imagine a breaker that has double lugs or triple lugs for 500 MCM conductors. How do you plan to make the connections?
 
power blocks

power blocks

Make the connections on a power block. I think they are technically called power distribution blocks. I have used them several times mounted inside a large J-box. One time we needed to step down conductor size. The others we needed to split the feed for vital and essential power panels. Parrelling circuits is common. Think about lighting and outlet circuits. All conductor must be current rated for the protection though, you can't assume half the current will go both ways.
 
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