National Electrical Installation Standards

Standards as High as Your Own

 
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Wednesday, July 27, 2022

Question:

Good Afternoon CQD.

A piece of mechanical equipment comes with a specified MOCP rating of 70A. It has an internal fuse that came with the equipment, sized appropriately. Is it breaking code to install a 90A circuit breaker to feed this equipment? Note wire is sized for 90A (breaker will indeed be protecting the conductors).

Harrison Korte

A

Answer:

Hi Harrison, thanks for the question. Based on the information provided our recommendation is to provide the 70-ampere overcurrent protective device in the equipment (usually a disconnect) that supplies the equipment. Sometimes the control panels are wired by the manufacturer with different protective features and wiring schematics. Providing the field-installed 70-ampere OCPD would be sure to meet the manufacturer's requirements and satisfy Section 110.3(B). hope this is useful. 

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IMPORTANT NOTICE: Unless the question requests a response based on a specific edition, all answers are based on the latest edition of NFPA 70® National Electrical Code®.

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