Sum of distro breakers amperage exceeds panel rating

[Gary Mazut]

Where in the code is it documented that the sum of output breakers amperage can exceed the rated/protected amperage of a distro panel? I am primarily concerned with commercial 3-phase distro. My understanding is that the panel must be rated/protected to account for the calculated load value. For example 480V 600A rated distro with 400A, 200A, & 100A distro breakers.

 

[roger]

Since this isn't a DIYer type question we will allow it and the answer is the NEC doesn't. Go to the load center in you house and add up the branch breakers, I'm sure they exceed the main rating.

 

[Johnhall30]

The panel rating is sized based on the calculated load, not the maximum load each breaker can handle.

 

[electrofelon]

For the most part, the code tells you things you CAN'T do, it doesn't have to give you permission or state things that you want to do are okay. 408.36 gives requirements for panel board over current protection.

 

[infinity]

My understanding is that the panel must be rated/protected to account for the calculated load value.

It's really two different questions. First the panel is sized to the calculated load. Second the OCPD ahead of the panel is sized to protect the panel. So if you had a 600 amp panel with a 600 amp feeder and a 600 amp calculated load it would be code compliant. The calculated load is not the sum of the size of the branch circuit breaker ratings.