National Electrical Installation Standards

Standards as High as Your Own

Wednesday, January 31, 2018


Re: CQD answer published Wednesday, January 16, 2018 -

Charlie, I don't agree with your answer on the 200A, 600 foot run.  The voltage drop will be 9.6 volts (8%) at full load. I think it's high time the NEC address voltage drop as a requirement vs. a 'suggestion' (or whatever an 'informational note' is). If this were my job, I'd run parallel 4/0 aluminum or 4/0 copper.

Dave Rutkowski



Hey Dave thanks for your comment, you have a good point that would be a much better design but at this time voltage drop limits are not a requirement for all feeders. Informational Note No. 2 to 215.2(A)(1) indicates that 3 % for feeders and 5% for the total will provide a reasonable efficiency of operation. Energy codes and manufacturer's instructions can also have requirements.

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ABOUT CHARLIE: 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. Charlie was also a member of NECA’s Academy of Electrical Contracting. Charlie’s experienced team of industry experts keep the CQD dialogue and discussions active and informative in the spirit of the man himself, as he wanted.

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