National Electrical Installation Standards

Standards as High as Your Own

Friday, September 1, 2023


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


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.

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