Minimum Circuit Ampacity Calculator

This calculator works out the minimum circuit ampacity and the maximum overcurrent protection for air conditioning and refrigerating equipment under NEC 2023 Article 440. Enter the rated-load current of the largest motor or compressor, the total of the other motors, and any non-motor load such as electric heat, and it returns the MCA, the 175 and 225 percent protection limits with the standard device size that fits under each, and the minimum disconnect rating. The MCA is 125 percent of the largest motor plus everything else, which is what 440.32 and 440.33 say in longhand. Whatever this returns, the MCA and MOCP marked on the equipment nameplate are the values you have to install to.