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.
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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.
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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.
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RE: [FEEDBACK] TECHNICAL QUESTION
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
7.2.1
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.
[This message has been edited by shockmaster21 (edited 10-30-2005).]
