National Electrical Installation Standards

Standards as High as Your Own

 
?
Friday, September 1, 2023

Question:

Hello CQD, thank you for providing this informational forum, I look forward to reading every morning. Does the NEC® define what is consider “LOW VOLTAGE” or “HIGH VOLTAGE” in my experience it is seems to be all over the place depending on who you talk to. If you ask an outside line worker, they consider 480V “Low Voltage” if you as a commercial construction electrician they consider 480V “High Voltage”. I am looking for something definitive I can share with my apprentice students. Thanks in advance and keep up great work, Ryan R
A

Answer:

Hello Ryan, thank you for the kind words, glad to hear you are enjoying the CQD. The NEC® does not define Low, Medium or High voltages. For this information you will have to reference another ANSI Standard. ANSI/NEMA C84.1-2020 Electrical Power Systems and Equipment – Voltage Ratings (60 Hertz) defines the voltage classifications in Section 3 and Table 1:

 Low Voltage - A class of nominal system voltage 1000 volts or less

 Medium Voltage- A class of nominal system voltages greater than 1000 volts and less than 100kV.

 High Voltage – A class of nominal system voltages greater than 100kV and equal to or less than 230kV.

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.