UL Requires American Standard-Sized Mounting Hardware

Question: Luminaires

Some luminaires imported to the United States are provided with metric hardware for mounting the fixtures. However, UL Listing requirements specify that fixtures be provided with American standard-sized mounting hardware. Is UL enforcing these requirements?


All UL Listed luminaires must be equipped with American standard-sized mounting hardware. Over the past few years, UL received a limited number of field reports regarding luminaries being provided with metric mounting hardware. UL Listed luminaires exported to the United States are required to be equipped with American standard-sized hardware.

However, should inspectors come across UL Listed luminaires that have not been provided with American standard mounting hardware, they must notify the nearest UL Regulatory Services representative. Once we receive the information, UL will open a Field Report and immediate appropriate action to resolve the issue. For more information on UL’s Regulatory Services, including contact numbers for representatives or to request a Field Report, accesswww.ul.comand click on “Regulators.”

Question: Isolated neon power supplies

Are isolated neon power supplies rated 7.5 kV or less specified in Section 600-23 of the NEC® covered by UL 2161?


Yes. Isolated neon transformers and power supplies rated 7.5 kV or less are still required to comply with UL 2161, the Standard for Neon Transformers and Power Supplies. Since power supplies of this size and type inherently comply with secondary ground fault test requirements; they are exempt from secondary ground fault testing as noted in UL 2161. Effective September 1999, UL 2161 requires all neon power supplies (other than cold-cathode) to be marked, “Complies with Secondary Ground-Fault Protection Requirements in UL 2161.”

Products complying with UL 2161 are Listed under the category Neon Transformers and Power Supplies (PWIK). The UL Guide information for this product category can be found on the UL Online Certifications Database atwww.ul.com. Or, consult page 66 in the 2000 edition of the UL General Information for Electrical Equipment Directory (White Book).

Question: Electrode receptacles for gas-tube signs

Does UL 879, the Standard for Electrode Receptacles for Gas-Tube Signs, cover polymeric boots intended for wet locations?


UL has recently developed requirements for polymeric insulators (e.g., polymeric boots) for use in wet locations that cover splices between neon electrodes and GTO cable. Currently, there is one Listing under the category Sign Accessories (UYMR).

These requirements are included in a UL Subject 879 Bulletin dated May 22, 2000. Presently, UL 879, the Standard for Electrode Receptacles for Gas-Tube Signs, is undergoing a complete revision and expansion of scope that will cover all types of sign components. The requirements for polymeric boots and sleeves have been proposed for inclusion in UL 879 and will remain the same, regardless if the revised Standard gets adopted. Revisions to UL 879 are currently under review by a UL Technical Committee.

Question: Low voltage lighting

Is there Listed cable that is permitted to be concealed in walls for low voltage lighting, other than NEC® Chapter 3 cable?


Currently, UL does not List standalone cable intended for use in concealed locations in accordance with the requirements of Section 411-4 of the NEC®.

Section 411-4 of the NEC® requires Chapter 3 wiring methods for concealed wiring. Chapter 3 covers wiring methods for all wiring installations, unless modified by other Articles in the code. Based on this reference to other NEC® Articles, powerlimited cable used in accordance with Article 725 can be used for low voltage lighting systems, provided that the cable is supplied by a Listed Class 2 or 3 transformer or power supply. However, since most power supplies provided with low-voltage lighting systems are not Class 2 or 3, Chapter 3 wiring methods are required, unless the cable provided with the Listed low-voltage lighting system was evaluated for concealment as part of the system’s Listing.

The proper cable would be specified in the installation instructions provided with the Listed system.

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