National Electrical Installation Standards

Standards as High as Your Own

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Tuesday, August 13, 2019

Question:

Charlie, I have a commercial 120/240V, 1 phase service with two main panels, each with a 200A, 2P main breaker.  The panels are located inside the building and are fed directly from the utility meterbase. The owner wants to install an exterior enclosed circuit breaker between the meterbase and each interior panel for maintenance purposes. The two new exterior circuit breakers will now become the service disconnects. There are presently two grounding electrode conductors, the primary one from the metal water service and a secondary attached to a driven ground rod. My question has to do with where to GECs must now connect. They presently are routed to both existing interior panel enclosures. I know the GECs along with the main bonding jumpers will have to be removed from those panels. With the proposed new arrangement, my understanding is that both GECs can land on the neutral bar in the existing meterbase if the local POCO allows. If not, can they be connected to the service neutral in only one of the new exterior circuit breaker enclosures or would they have to be routed to both new enclosures?

Thank you for your service to the electrical community! K. Hall
A

Answer:

Hey K. Hall thanks for your question and the kind words. Yes, a grounding electrode conductor can be connected to the grounded conductor in the meter socket enclosure as stated in 250.64(D)(3)(1) if as you mention if the utility does not prohibit it. If individual grounding electrode conductors are installed, they must be connected to each service equipment disconnecting means as stated in 250.64(D)(2)(1).

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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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