Code Change Summary: Section 230.66 was revised to focus solely on marking of service equipment, with listing language moved to new 230.2 and meter-socket rating provisions relocated to 230.68.

SME commentary: In the 2026 NEC^®, Section 230.66 is streamlined so users will find only the marking requirement for service equipment. The prior 2023 text bundled several concepts into one place. It required service equipment rated at 1000 volts or less to be marked as suitable for use as service equipment, and it also repeated the directive that all service equipment shall be listed or field evaluated. The 2026 rewrite removes duplication and clarifies the code sections focus by moving the listing requirement to new Section 230.2, titled “Listing Requirements,” which is consistent with the NEC^® Style Manual guidance to place product listing rules in the .2 subdivision of each article. Installers and inspectors now have a single location in Article 230 to confirm which service equipment must be listed, and when a field evaluation may be acceptable.

The voltage qualifier “rated at 1000 volts or less” is also removed from 230.66. That phrase is no longer necessary because Article 230 covers services within that range by scope and a new Article 268 addresses services over 1000 volts ac and 1500 volts dc. Eliminating the redundant qualifier keeps the marking rule concise without changing its intent or application for typical service installations.

The remaining text in 230.66 focuses on what must appear on the equipment. Service equipment shall be marked to identify it as “suitable for use as service equipment” or “suitable for use only as service equipment.” The second phrase is important. Some assemblies are designed and listed only for use as service equipment with a factory connection made from the grounded conductor terminal to the equipment grounding terminals, and NOT intended to be feeder-supplied with neutrals and equipment grounds separated. Recognizing both markings in the rule helps prevent misapplication in downstream locations while still allowing manufacturers to provide either convertible or service-only designs.

Another organizational improvement is the relocation of meter-socket rating provisions and the associated exception for utility-supplied equipment. Those requirements were previously embedded in 230.66(B). They are now addressed in new Section 230.68, which keeps component-specific criteria separate from the general marking rule.

The practical effect is improved usability. When verifying a service installation, the user first confirms listing status in 230.2, then confirms the required service suitability marking in 230.66, and finally looks to 230.68 for meter-socket ratings and exceptions. The technical requirements are unchanged in substance, but they are presented in a clearer structure that reduces cross-talk between listing, marking, and equipment ratings. This reorganization makes Article 230 easier to teach, easier to inspect, and easier to apply in plan review and in the field.

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 2026 NEC^® edition of NFPA 70.

2023 Code Language:

230.66 Marking.

(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.

(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.

2026 Code Language:

230.66 Marking. Service equipment shall be marked to identify it as being suitable for use as service equipment or suitable for use only as service equipment.