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Friday, October 27, 2023

Question:

Good morning, occasionally manufacturer’s installation instructions will contradict the requirements of the NEC®. I know that the manufacturer can require things above and beyond the requirements of the NEC®, but can the manufacturer installation instructions be less restrictive than the NEC® minimum? If so, what rules do we follow? Best, Rick
A

Answer:

Hello Rick, great question. The manufacturer’s installation instructions are part of the listing of a that equipment or product, as such to maintain the listing of that equipment or product the instructions must be followed even if they are more restrictive than the NEC®. In the rare occurrence the installation instructions are less restrictive than the NEC®, then the more restrictive requirements of the NEC® would take precedence. While it does happen, it is not very common as most electrical equipment and product standards are written with the NEC® in mind. Also, the NRTL that evaluates the equipment or product will often require the manufacturer to address the conflict in the instructions before providing the listing approval. Occasionally, this will happen when a new edition of the NEC® comes out, and the instructions are not updated. However, it can also be an indication of a product that is not listed or is bearing a listing mark without authorization. When these situations arise, it is advisable to contact the manufacturer and/or NRTL that has listed the product so it can be investigated and resolved.  

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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.

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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®.

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. 

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