National Electrical Installation Standards

Standards as High as Your Own

Thursday, September 28, 2023


Good morning, Charlie, I am writing regarding a previous CQD answer given for the question on June 7th, regarding concrete encased electrodes for a new garage supplied by a feeder. The garage was built, and the footings were poured containing rebar that qualifies as a concrete electrode. There was no accommodation made to permit connection to the concrete encased electrode. Does the electrical contractor have to connect to the concrete encased electrode? The answer indicated that a concrete encased electrode would be required in compliance with Section 250.52(A)(3) but no mention of the exception was made. The Exception to Section 250.50 states:

Concrete-encased electrodes of existing buildings or structures shall not be required to be part of the grounding electrode system if the rebar is not accessible for use without disturbing the concrete.

My understanding is that this exception was put in place for this very reason, the intention is such that if the footings are poured and the rebar encased prior to the electrician arriving on site to perform the wiring, then the concrete does not need to be disturbed to make the connection. Clarification on this topic would be great. Regards, Joe Jones


Hello Joe, thanks for the insight and information. Your comments are correct regarding the exception to Section 250.50. The intent of that exception is to ensure existing installations are not disturbed and an existing building or structure could be one that is 2 years old or one that is 2 days old. Many General Contractors and Building Inspectors are aware of the requirement for a concrete-encased electrode, as such it has become a relatively common practice to provide accommodations for the electrician to make the connection after the footings are poured. However, in a situation where there is a truly honest mistake and the accommodations were not made, the exception is there to provide relief. Additionally, there is an alternative to connecting to the rebar, Section 250.52(A)(3)(2) permits the installation of a concrete-encased electrode made up of bare copper conductor not smaller than a #4 AWG. It is also advisable to check with your AHJ, as each local jurisdiction may handle this uniquely with local ordinance or state statute.

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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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