Existing Feeders

[Turk1957]

If a Mechanical Engineer changes the requirements for an existing Rooftop Unit, and the MCA changes from 125A. down to 84A. , is it permissible to leave the existing 125A. feeders in place, in lieu of changing them out to accommodate the revised 84A. load?

 

[infinity]

As you've stated the MCA is the minimum conductor ampacity so it's fine to exceed the minimum. You might need to change the OCPD if it exceeds the MaxOCPD rating of the unit.

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