When to use: Use this calculator when designing motor branch circuits for HVAC equipment, pumps, fans, compressors, and industrial machinery. NEC Article 430 has specific requirements for motors that differ from standard branch circuits — conductors must be sized at 125% of FLA (NEC 430.22), overcurrent protection at 150–300% of FLA (NEC 430.52), and overload protection at 115–125% (NEC 430.32). Using standard branch circuit rules for motors is a common — and dangerous — mistake.