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 covers boxes but has no specific requirement that all box types 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 the following specific rules on product listing where the NEC^® is silent.

24.1-06-01-10, note 2. All wiring materials and equipment shall be listed by nationally recognized testing laboratories to safeguard life and property. It is the duty of the electrical installer to secure permission from the executive director to use materials, devices, and methods of installation not specifically covered by these standards. Equipment not approved under a testing laboratory category shall be evaluated by a registered professional engineer and recorded on evaluation forms accepted by the board.

Exception: Manufacturing firms that install industrial machinery for use by the firm itself and employ professional engineers may evaluate the industrial machinery according to NFPA 79 or UL 508 Standards. This evaluation shall be maintained with the equipment at all times and a copy submitted to the board.
Refer to the Laws, Rules and Wiring Standards of North Dakota for additional information.