National Electrical Installation Standards

Standards as High as Your Own

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Wednesday, January 2, 2019

Question:

Re: CQD answer published Wed, December 19, 2018 -Meter Disconnect Switches

"Charlie" no need to publish my comments but it seems Carl the questioner is mixing apples and oranges. The cold sequencing switch is indeed required in NJ for certain size services but I am not sure it has to have an AIC rating since it is a non-fused switch. The disconnect that is immediately after the meter socket is the one that is a fused switch (or it could actually be a circuit breaker if someone desired that) and that is the one which requires the AIC rating. Also the grounding electrodes and grounding electrode conductors do not appear until the main disconnect is reached. There are no grounding conductors to be installed in the cold sequencing switch. The cold sequencing switch is strictly a safety to be used by the utility to allow their employees to remove and install the meters while not under load. Another point is that the cold sequencing switch is bonded by the neutral or ungrounded conductor similar to the meter socket or CT cabinet bonding. Looking forward t tomorrows response. Keep up the good work and Merry Christmas to all.

Rich Van Wert

A

Answer:

Rich thanks for your follow up comment and compliment. Meter disconnect switches are allowed on the supply side of the service disconnect as stated in 230.82(3). But they must have a short-circuit current rating (SCCR), as that term is defined in Article 100, at least that of the available short circuit current as stated in that section. True, the switches can be installed to help utility personnel do their work in a safer manner, but they are often part of premises wiring as that term is defined in Article 100 because they are on the load side of the service point, also defined in Article 100. As the submitter mentioned non-fusible enclosed switches are not available with SCCR's above 10 kA so if the available fault current exceeds that, the switch would need to be a fusible type to achieve that rating. See 110.9 and 110.10 for additional information.

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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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