National Electrical Installation Standards

Standards as High as Your Own

 
?
Thursday, August 24, 2023

Question:

Hello Code Friends, I am working on new building where a fire pump is being installed. We installed a separate 277/480V, 400A service for the fire pump. The fire pump controller is service rated with integral OCPD, and part of a listed package with the 100 H.P. fire pump motor. We called for a service inspection to get the fire pump service approved, and the inspector failed the service stating the transocket for the fire pump service needed to be sized for the Locked Rotor Current (725A) of the Fire Pump motor 460V 100HP. The code section the inspector cited was 695.4(B)(2)(a)(1). Does the transocket need to be sized for the Locked Rotor Current? Thanks for your help in this matter, Frank Tracinski  
A

Answer:

Hi Frank, thanks for your question. This one comes up from time to time and there are a few things at play here. In this scenario it sounds like the inspector may be misapplying the requirements found in Section 695.(B)(2)(a)(1). The requirements of Section 695.4(B)(2)(a)(1) apply when the power supply to a fire pump motor is by a traditional service with a service disconnect/OCPD. Then the OCPD must be sized to accommodate the Locked Rotor Current (LRC) of the fire pump motor, and Full Load Current (FLC) of any jockey/maintenance pump motors. This applies to the OCPD devices only and by relation the disconnect housing the OCPDs. This Section does not apply to the supply conductors, and any other associated equipment (including the transocket). The other key thing to mention is that you have installed a listed fire pump controller and fire pump motor assembly, which has different OCPD requirements covered by Section 695.4(B)(2)(a)(2).    

ABOUT CQD: The Code Question of the Day (CQD) is NECA and ELECTRICAL CONTRACTOR Magazine’s flagship National Electrical Code (NEC®) public forum for the industry, sponsored by EATON. The daily distribution of Q&A generates a lively dialogue and shares relative Code-based practical responses.

SUBMIT YOUR CODE QUESTION: Click here to submit a question to for inclusion in an upcoming edition of the Code Question of the Day, or email codequestion@necanet.org

CHARLIE TROUT: Charles M. Trout, better known as Charlie, was a nationally known NEC® expert and author. He served on several NEC® technical committees and is past chairman of CMP-12. In 2006 Charlie was awarded the prestigious Coggeshall Award for outstanding contributions to the electrical contracting industry, codes and standards development, and technical training. Even though Charlie passed away in October of 2015, his work continues in spirit. NECA continues to maintain this question forum for its many subscribers in memory and recognition of all his significant contributions to making the NEC what it is today.

NECA STANDARDS: NECA publishes the National Electrical Installation Standards™ (NEIS™), a series of ANSI-approved performance and quality standards for electrical construction. NEIS can be purchased in the NECA Store in three formats: a printed or  PDF download of a standard or, as an  annual subscription service.

NECA SAFETY PRODUCTS & PUBLICATIONS: NECA produces electrical safety publications and products for the industry including jobsite safety guides, handbooks and resource kits. View a full listing of available resources and products »

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®.

This correspondence is not a formal interpretation of the NEC® and any responses expressed to the questions are opinions and do not necessarily represent the official position of NECA, NFPA, the NEC Correlating Committee any Code-making panel or other electrical technical committee. In addition, this correspondence is neither intended, nor should it be relied upon, to provide professional consultation or services. 

UPDATE YOUR SUBSCRIPTION PREFERENCES: Subscribe or Unsubscribe from this list.