Q. When does the NEC require a main breaker in a load center?

A. Each lighting and appliance branch-circuit panelboard must be protected on the supply side [408.16(A)]. The overcurrent protection device can be located within the panelboard, or the panelboard’s feeder overcurrent protection device could be used if its rating doesn't exceed the ampere rating of the panelboard [408.16(A) Ex.1].

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