National Electrical Installation Standards

Standards as High as Your Own

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Tuesday, December 18, 2018

Question:

Good Morning, I begin my mornings with your questions and answers, which is very informative and a great learning experience. In a portion of NJ where there are multiple electric utility providers, we have a situation, which is not unique to the entire State but where this Utility exists it’s now become an issue.  They have begun to require a Disconnecting means ahead of the meter for any 277/480V services and/or CT cabinet for “Cold Sequence” so they may work on their equipment without having to shut down transformers or disconnect the service.  As an electrical inspector and a member of the Code Advisory board in NJ, my interpretation of 230.82 is that this is considered a “Meter Disconnect” not service equipment, therefore no grounding is done in this enclosure and after the installation the disconnect will be locked by the Utility.  In our state we are not allowed by this particular Utility to install the GEC in either the meter enclosure or CT cabinet. My interpretation also is this “Disconnect” must have the appropriate AIC rating which would be provided by the utility, and here lies the issue. I’m not aware of any non-fused disconnect which has an AIC rating of more than 10,000, therefore most times, it must contain OCP either with fuses or a CB to meet the available AIC as per the utility.  Some members of our committee believe since there is overcurrent protection in this enclosure, this is considered the “service disconnect” and the GEC must be brought to this enclosure. My contention is as per 230.82 it is not, and the “Service Disconnect” will be on the load side of this “Meter Switch”, in which ever configuration it may be.  Switch gear is generally not an issue since most manufactures will construct the switchgear with the “Service Disconnect” ahead of the CT compartment and the compartment with the branches. Again in switchgear the ability to install the GEC is easy since the Neutral bar extends into the branch cabinet. Your comments please and thank you for your time.

THANK YOU, CARL GURNEY

A

Answer:

Hey Carl thanks for your question and the kind words. You are correct, meter disconnect switches are allowed on the supply side of the service disconnecting means as stated in 230.82(3). They must be field marked METER DISCONNECT, NOT SERVICE EQUIPMENT and can help make it easier to work on downstream equipment in an electrically safe work condition as required by NFPA 70E. The grounded conductor can be used to "ground" the switch enclosure as stated in 250.142(1). If fuses are necessary in the enclosed switch to achieve the sufficient short-circuit current rating required by 230.82(3) that doesn't make it service equipment.

A wise inspector once stated that a key word in the definition of Service Equipment is "intended". The circuit breaker or fused switch that is intended to be the main control and cutoff of the supply is the service equipment which in your example is on the load side of the meter disconnect and meter.

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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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