Selection of Overload Device for Continuous-Duty Motor

When an overload device sized in accordance with 430.32(A)(1) and (B)(1) is not sufficient to start the motor, higher size sensing elements shall be permitted if the trip current does not exceed ____% of the motor nameplate full-load current rating, when the motor is marked with a service factor of 1.12.

a) 100
b) 110
c) 125
d) 130

See answer and applicable Code reference

The correct answer is: d) 130

Article 430 covers the requirements for motors, motor circuits and controllers. Part III of this Article focuses on motor and branch-circuit overload protection requirements. As noted in Sec. 430.32(C), motors marked with a service factor 1.15 or greater can use a sensing element with a trip current rating of up to 140% of the motor nameplate full-load current rating. The same holds true for motors with a marked temperature rise 40°C or less. All other motors are limited to 130%.

 

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