230.66 Marking.

Meter sockets shall be listed and rated for the voltage and current rating of the service unless supplied by and under the exclusive control of an electric utility.
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Meter sockets shall be listed and rated for the voltage and current rating of the service unless supplied by and under the exclusive control of an electric utility.

Code Change Summary: Reorganized code section pertaining to marking of service equipment.

The existing marking requirements in 230.66 have been reorganized into a list for clarity. These marking requirements are for the manufacturer and are not field marking requirements.

The NEC® is used by electricians, inspectors, insurance adjusters, some utility companies and equipment manufacturers. For the manufacturer of a meter socket, product certification (listing) is critical in order to be able to sell a safe product and have no issues during the electrical inspection. There are many Nationally Recognized Testing Laboratories (NRTL) approved by OSHA to certify (list) products. Underwriters Laboratories (UL) is one of several.

For the installing electrician, complying with the rules in this section means purchasing a listed meter socket enclosure unless the meter socket enclosure is being supplied by and under exclusive control of the electric utility provider.

Below is a preview of the NEC®. See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2020 NEC® edition of NFPA 70.

2017 Code Language:

230.66 Marking. Service equipment rated at 1000 volts or less shall be marked to identify it as being suitable for use as service equipment. All service equipment shall be listed or field labeled. Individual meter socket enclosures shall not be considered service equipment but shall be listed and rated for the voltage and ampacity of the service.

Exception: Meter sockets supplied by and under the exclusive control of an electric utility shall not be required to be listed.

2020 Code Language:

230.66 Marking.

N (A) General. Service equipment rated at 1000 volts or less shall be marked to identify it as being suitable for use as service equipment. All service equipment shall be listed or field evaluated.

N (B) Meter Sockets. Meter sockets shall not be considered service equipment but shall be listed and rated for the voltage and current rating of the service.

Exception: Meter sockets supplied by and under the exclusive control of an electric utility shall not be required to be listed.

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230.66 Marking.

Below is a Real Question from our Electrical Continuing Education Courses for Electrical License Renewal:

Refer to the image of the electric meter socket:

Which of the following is true?

A: The meter socket is UL listed.
B: The meter socket is NOT listed.
C: All meter sockets under the exclusive control of an electric utility shall be listed.
D: Utility meter sockets shall NOT be listed.
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