National Electrical Installation Standards

Standards as High as Your Own

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Thursday, July 23, 2020

Question:

Greetings Code Gurus,

I have 1/3 hp motors 3 phase 480 volt with a 20-amp twist lock plug. The overcurrent device is 15-amps. Article 430.53 (A) limits my overcurrent protection to 15-amps. But article 210 table 210.21 (B)(3) prohibits a 20-amp device on a 15-amp circuit. My problem is there is not a 480-volt, 15-ampere, 3 phase name configurations. So is there a problem or does the code address this issue. So, what the correct solution?

Thank you,

Walter Vaeth

A

Answer:

Hello Walter,

Based on the information in the question, the branch circuit short circuit and ground fault protective device can be sized in accordance with Article 430, Part IV for several motors installed on a 15-ampere branch circuit as long as the conditions of 430.53(A) items (1) through (3) are met. In this instance the rules in Article 430 would apply. See Sections 210.3 and 240.3 which refer to Article 430 for motors.

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