How do I size a motor and its disconnect?

To size an electric motor, you need to know the FLA (Full Load Amps) and LRA (Locked Rotor Amps). These values are found on the motor nameplate or in the Code tables.

Sizing rules:

• Motor conductor: 125% of FLA (Article 28-106)
• Breaker: 250% of FLA for a standard breaker, or 125% of FLA for hermetic motors
• Disconnect: must be able to interrupt at least 100% of FLA and withstand fault current
• VFD (Variable Frequency Drive): must be sized for the motor's input current, not just the rated power

Example: 10 HP motor, 208 V, FLA = 30.8 A. Conductor = 30.8 × 1.25 = 38.5 A → #8 AWG. Breaker = 30.8 × 2.5 = 77 A → 80 A breaker.