Code Q&A: Air-Conditioner Calculations

NEC rules for sizing the conductor and overcurrent protection for an air-conditioner

Q. How do I size the conductor and overcurrent protection for an air-conditioner? (Answer based on 2011 NEC.)

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A. The short circuit and ground fault protective device for a single motor compressor must not be more than 175% of the motor compressor current rating. If the protective device sized at 175% isn’t capable of carrying the starting current of the motor compressor, the next size larger protective d

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