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Friday, May 14, 2021

Question:

Hi CQD,

Thanks for this informative Code blog. If a ground-mounted A/C unit (for a split system) is marked "Minimum Circuit Amperes" 30 and Maximum Overcurrent Protective Device 55, do I have to size the wire for 55 amperes?

Tom Hearn

A

Answer:

Hi Tom,

Based on the information in the question, the nameplate takes precedent here. These units are typically listed equipment that contains hermetically sealed motor compressor(s) and multi-motor and combination load equipment and wiring is addressed in Article 440. The wire has to be capable of handling 30 amperes after any correction factors are applied. The OCPD can be sized up to 55 amperes maximum. This usually accounts for starting current. The combination of the OCPD and the overlad protection inside the unit provide the total overcurrent protection for the equipment. See Sections 110.3(B) and 440.4(B).

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