For maximum motor protection and compliance with Article 430-32 of the National Electrical Code, select heater coils from the tables in this section on the basis of motor nameplate full load current.
When the full load current is unknown, selection may be made on the basis of average full load currents as shown HERE (Motor Rating Data)
Caution—The average ratings could be high or low for a specific motor and therefore selection on this basis always involves risk. For fully reliable motor protection, select heater coils on the basis of full load current rating as shown on the motor nameplate.
Heater coils are rated to protect 40°C rise motors, and open and drip-proof motors having a service factor of 1.15 where the motor and the controller are at the same ambient temperature.
