According to NEC Section 440.7, the largest motor is considered the one that ________.

• A. Has the highest full-load current
• B. Has the highest starting current
• C. Draws the most peak current
• D. Is the physically largest motor

Answer: (A)

The biggest motor is identified by the one that has the highest full-load current. That full-load current is the steady, running current the motor draws when delivering its rated output, and NEC uses this value to size conductors and overcurrent protection for a circuit that serves multiple motors. Starting and peak currents are transient inrush and don’t reflect normal operating load, so they’re not used to determine which motor is considered the “largest.” Also, a motor that’s physically larger isn’t guaranteed to draw more current than a smaller one if efficiency and design differ. So the motor with the highest full-load current is the one that sets the circuit requirements.