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Dear Friends,
Sincere best wishes to all of you! I am presently working as a journeyman electrician on the remodeling of an exhibit/shop/promotion for Coca-Cola at Walt Disney World. On Thursday the job foreman displayed concern that some pendant light fixtures had been installed and the 1" X 8-32 machine screws provided by the manufacturer had not been used to attach the fixture plate to the 4" to round plaster ring mounted on the outlet box. Instead (in most instances) , we had used 1/2" X 8-32 machine screws (industry standard, and produced by a major manufacturer) to secure the fixture plate to the plaster ring. In every instance there was direct metal to metal contact between the fixture plate and plaster ring, and at least 1/4" of the machine screw was visible inside of the box. However, the foreman claimed that since the 1" X 8-32 machine screws provided by the fixture manufacturer was not used, this was a potential violation of the UL listing of the light fixture and potentially exposes the electrical contractor (and individual electrician) to increased liability. Now, of course, there was no question that unauthorized "field alterations" to fixtures, devices or other equipment will, in fact, violate the provisions of that items UL listing. For instance, failing to use the provided light fixture installation plate will render the UL listing invalid because such plates are necessary for heat dissipation, grounding and/or other purposes. But, the specific issue here was whether or not the act of not using the factory provided screws was a violation. Have you any specific knowledge or comments concerning this issue. If possible, a speedy answer would be very much appreciated. Thank you very much and take care!

James E. Shepherd Jr.

(Personal Contact info removed - Responses can be made here, or via the PM Feature)

[ October 22, 2005, 07:48 PM: Message edited by: bill addiss ]



Use the UL approved screws chop em off to the same length. Apprciate the extra work and laugh all the way to the bank over stupidity.

jim dungar

Staff member
Retired Electrical Engineer - Power Systems

There is no such thing as a UL approved screw.

Only the AHJ can make the decision that the installation is no acceptable . UL is glad to assist the AHJ in making the evaluation.


Senior Member
Northern illinois

Originally posted by jim dungar:
Only the AHJ can make the decision that the installation is no acceptable .
Thats not true. The boss can also make that determination. the AHJ can only determine whether the installation meets the minimum standards set by the NEC or whatever passes for an electrical code in that jurisdiction. There is nothing that prevents an employor from demanding a higher/different standard. The end user can also make that determination. In fact, basically everyone involved has to come to the conclusion that the installation is acceptable, often using different criteria, or it is in fact not acceptable.

[ October 26, 2005, 02:28 PM: Message edited by: petersonra ]

Hi, all,
Thanks for your input and insight. As I thought, exploring this issue has proven to be interesting and informative. FYI, here are some comments from UL and NEMA. Sorry about the length.
An authorized use of the UL Mark is a manufacturer?s declaration that a product was originally manufactured in accordance with the applicable requirements when it was shipped from the factory. When a UL Listed product is modified after it leaves the factory, UL has no way to determine if the product continues to comply with the safety requirements used to certify the product without investigating the modified product. UL can neither indicate that such modifications ?void? the UL Mark, nor that the product continues to meet UL?s safety requirements, unless the field modifications have been specifically investigated by UL. It is the responsibility of the regulatory authority to determine the acceptability of the modification or if the modification is significant enough to require one of UL?s Field Engineering Services staff to evaluate the modified product. UL can assist the regulatory authority in making this determination.
If a party would like UL to determine if the modifications made to a UL Listed product comply with UL requirements, the appropriate Field Engineering Service can be initiated to investigate the modifications. This investigation will only be conducted after UL consults with the regulatory authority to assure that UL?s investigation addresses all areas of concern and meets all of the regulatory authority?s needs.
A field evaluation of a product can also be performed by UL for field certification of products that have not previously been evaluated or certified by UL. - From THE CODE AUTHORITY:ELECTRICAL CONNECTIONS (August - 2004) published by the Regulatory Services Department of Underwriters Laboratories, Inc.

Unless otherwise noted, the UL Mark applies to a product as it is originally manufactured?that is, as it left the factory. An exception to this is when a product has markings or instructions for such modifications (i.e., adding grounding kits for panelboards or trim rings for recessed luminaries). Only authorized accessories should be used.
Note: A modification may be intentional ( such as a repair) or accidental (such as dropping the
product). UL cannot know what effect any modification (alteration, repair or accident) may have on safety, code compliance, performance on the continued UL certification of the product unless specifically evaluated by UL. - From THE CODE AUTHORITY:ELECTRICAL CONNECTIONS (July 2004) published by the Regulatory Services Department of Underwriters Laboratories, Inc.



Thanks for contacting NEMA with you question regarding support of luminaires.

First and foremost, the manufacturer's instructions provided with each luminaire should be read and followed as required in 110.3(B) of the NEC. If the screws that are provided with the product are critical as to length, strength, corrosion protection or material, it will state that and no substitution should be made. In addition, the manufacturer may provide components with the product that are not required by the standard or the listing for the convenience of the installer, or may substitute components that exceed the minimums required by the listing. An example might be the twist-on wire connectors supplied with many luminaires. Often these connectors are small and suitable only to connect the fixture wire to a single supply conductor. If the supply consists of several conductors, a different connector may be substituted in order to make a safe and compliant installation. In cases such as this, the manufacturer provided the connectors as a convenience.

The standard used to evaluate luminaires for use in the United States is UL 1598. The section on proper installation of a surface mounted luminaire, Section 7.2, states:
"7.2 Mounting means
A luminaire intended to be directly mounted to an outlet box shall be provided with two No. 8-32 machine screws if the luminaire surface containing the mounting screw holes is more than 3.2 mm (0.125 in) from the mounting surface. The length of each screw shall be at least 13 mm (0.5 in) plus the distance from the mounting surface to the luminaire surface that contains the screw holes."

Please note that this section of the standard refers to luminaires mounted directly to an outlet box, not to a pendant type luminaire. I could find no reference specifically to mounting a pendant luminaire, so I am using the above as a general requirement. Note that the section requires the manufacturer to provide two 8-32 machine screws, and that the length must be .5 inches plus the distance to cover any recess from the surface to the threaded holes in the box. It is entirely possible that the manufacturer provided longer screws to address situations where the distance from the box to the mounting surface is up to .5 inches, in which case the screw provided will still comply with the standard. If this distance is less than .5 inches, then other length screws would also comply with the standard.
In conclusion, I can offer the following:

1. The manufacturer's installation instructions must be followed. If the provided screws are required to be used in the instructions, than no substitutions should be allowed.
2. Absent any specific instructions, then substitution of a different length screw should not result in any reduction in safety for the installation, provided that:
A) The screw has full engagement of all threads into the threaded holes in the box.
B) The screw meets or exceeds the manufacturer's screw in terms of strength, diameter, and corrosion protection.

I hope this helps to address your concern. Please understand that the information provided here is general in nature and should not be used to override the manufacturer's instructions or listing requirements.

[ October 30, 2005, 09:07 PM: Message edited by: shockmaster21 ]

The most definitive answer to date comes from an e-mail sent to me from a Senior Customer Service Engineer(Lighting)with Underwriters Laboratories. He states:

"The length of the screws packaged with the luminaire takes into account that there are installations that involve different spacings between the luminaire and the junction box. Also, it permits the manufacturer to use one set of screws for many different luminaire models, thereby reducing their inventory. The clause in UL 1598 that addresses the length of luminaire mounting screws is 10.2.1. It specifies that the length of the screw has to be at least 1/2 in. longer than the distances between the mounting surface and the luminaire surface with the screw hole.

You have elected to replace those screws with shorter screws of the same diameter and thread pitch. The use of those shorter screws that protrude past the other side of the threaded hole by at least 1/4 inch are sufficient to secure the luminaire. This does not void the UL Listing.

Very best regards,"

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