The conductors and the equipment required or permitted by this code shall be acceptable only if they are what?

• A. listed
• B. UL listed
• C. approved by the AHJ
• D. field tested

Answer: (A)

The main idea is that electrical equipment and conductors used under the code must have undergone formal evaluation by a recognized testing laboratory and bear a listing. Listing means the product has been tested and shown to meet applicable safety standards and carries a certification mark. The code uses the general term “listed” to cover listings from any recognized lab (UL, CSA, ETL, etc.), not just UL specifically. That’s why this is the correct requirement: it ensures consistent safety and performance across installations.

Being specifically UL listed is an example of listing, but the code doesn’t require UL as the sole path; it accepts listings from any recognized laboratory. Relying on AHJ approval alone isn’t the same as listing and doesn’t provide the same standardized assurance. Field testing by itself also doesn’t substitute for listing, since listing provides pre-approved, standardized evaluation of safety and performance.