National Electrical Installation Standards

Standards as High as Your Own

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Thursday, November 30, 2017

Question:

Thanks for the service you provide to our industry. How do you apply NEC 430.6 to 277V single-phase motors? There is no 277V column in Table 430.248.

Steven Bunker

A

Answer:

Hey Steven thanks for your question and the compliment. If the Table voltages referenced in 430.6 do not include the specific motor voltage or voltage range that applies to a motor, such as 277 there really is no option other than to use the motor manufacturer's information including the nameplate. Make sure the motor complies with other applicable portions of Article 430 such as 430.7. It is also possible the motor is intended as a replacement that is part of a motor operated appliance.

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