National Electrical Installation Standards

Standards as High as Your Own

Thursday, May 13, 2021



Would I be correct in saying, a sub-panel does not need a MCB (meaning it would be a MLO panel), as long as the feeders to it are protected by a correctly sized circuit breaker from the main panel (or the panel feeding it), even if the sub-panel is located in a separate building? Would the only code section needed for an answer be 240.21? Thank you for your help on this.

Sal Genovesi



Hi Sal,

Thanks for the question.  If the panelboard remains installed in the same building it could be a main lug only type and a main is not required. Based on your questions, if the panelboard is installed at a separate building or structure on the feeder supplying the building or structure would need to comply with Sections 225.31 and 225.32 which addresses the location and 225.33 addresses the maximum number of disconnects and grouping. The panelboard in this case, should be suitable for use as service equipment in accordance with 225.36.

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