When a branch circuit supplies an air conditioning system that consists of a hermetic motor-compressor and other loads, the circuit rating must not exceed 125 percent of the hermetic motor load plus the sum of the additional loads.
Why must this not be exceeded
When a branch circuit supplies an air conditioning system with a hermetic motor-compressor and other loads, the circuit rating must not exceed 125% of the hermetic motor load plus the sum of the additional loads.
This guideline ensures that the circuit can accommodate the starting current, often higher than the running current, required by the hermetic motor-compressor during startup.