Product certification (listing) is generally done by Nationally Recognized Testing Laboratories (NRTL’s).

Many (but not all) NEC^® Articles specifically require electrical equipment and wiring materials to be listed. NEC^® Section 410.6 requires all luminaires, lampholders, and retrofit kits to be listed. NEC^® Article 240 addresses overcurrent protection such as fuses and circuit breakers but has no specific requirement that all overcurrent devices must be listed.

NEC Article 100 defines “listed” as follows:

Listed. Equipment, materials, or services included in a list published by an organization that is acceptable to the authority having jurisdiction and concerned with evaluation of products or services, that maintains periodic inspection of production of listed equipment or materials or periodic evaluation of services, and whose listing states that either the equipment, material, or service meets appropriate designated standards or has been tested and found suitable for a specified purpose.

The State of North Dakota has specific rules on product listing where the NEC^® is silent. Refer to the Laws, Rules and Wiring Standards of North Dakota for additional information.