Can low-voltage luminaires marked “for recreational vehicle use” be used in other locations?

Question: Low-voltage luminaires

Can low-voltage luminaires marked “for recreational vehicle use” be used in other locations?



Luminaires intended for RV use are listed under the category Low Voltage Luminaires for Recreational Vehicle Use (IFDQ) located on page 48 in the 2003 General Information for Electrical Equipment Directory (the White Book). The guide information states: “This category covers incandescent and fluorescent lamp type luminaires rated 24 V or less, AC or DC, intended for use in recreational vehicles, supplied by a transformer, battery, converter or similar power supply source and installed in accordance with the National Electrical Code.” The NEC reference is Article 551. Luminaires listed under (IFDQ) have not been listed for installation in other than recreational vehicles.

Question: Semiconductor equipment

Can UL list semiconductor manufacturing equipment?



Yes. The product categories are:
—Analysis and Measurement Equipment (TWLR)
—Automation and Wafer Handling Equipment (TWPV)
—Control Panels (TWRF)
—Liquid Chemical Distribution Systems (TWSP), all located on page 105 in the 2003 General Information for Electrical Equipment Directory (White Book); and,
—Misc. Equipment (TWTZ)
— Power Supplies (TWVJ)
— Process Equipment (TWWT)
— Limited Production Semiconductor Manufacturing Equipment (TWWU), all located on page 106 in the 2003 White Book.

Question: Arc flash marking

Does UL require an arc flash marking, as described in 2002 NEC Section 110.16, for panelboards, industrial control panels, motor control centers, and switchboards?



UL does not require an arc flash marking because the NEC requires this marking be applied in the field, not the factory, and only requires the marking under specific installation dependent criteria.

Question: Ground clamps for rebar

Are there listed ground clamps for rebar?



Yes, ground clamps that have been specifically evaluated for use on concrete-encased rebar are listed under the category Grounding and Bonding Equipment (KDER) located on page 59 in the 2003 General Information for Electrical Equipment Directory (the White Book). The ground clamps are marked with the size of the rebar and the size range of the grounding electrode conductor.

Question: Deadfront switchboard

Often, installation instructions get lost for switchboards after they are installed. When the instructions for a bottom-feed-only conduit installation get lost after the unit is installed, it is hard for the AHJ to inspect the installation at a later time.



According to the information published in UL’s “Deadfront Switchboard Marking Guide” (Section 12), all deadfront switchboards are evaluated for bottom feed in compliance with the 2002 NEC Section 408.10. If the conduit entry is some other location than the bottom, the installation must comply with NEC Section 408.3(F). The intended location of the conduit entry, if it is other than the bottom, will be identified in the manufacturer’s drawings, or in the installation instructions.

The deadfront switchboard marking guide as well as marking guides for other types of products are available online at

 Question: Switchgear

If switchgear is comprised of a number of switchboard sections, shouldn’t each section be labeled?



Yes, each section should be labeled. Switchboards are listed under the category Switchboards, Deadfront (WEVZ), located on page 115 of the 2003 General Information for Electrical Equipment Directory (the White Book). In addition to using the White Book, you can also locate the UL Guide Information using the UL Online Certification Directory, just click on the “category code/ guide information” search and enter the four character category code, in this case the category code is “WEVZ.”

The guide information states that listing marks for deadfront switchboard sections contain “_________ OF __________.” The first space is stamped with a number indicating the position that the section occupies in the series of sections constituting the switchboard. The latter space is stamped with the total number of sections in the switchboard (including sections not bearing a UL listing mark).

A listing mark covers only the section so marked; it does not cover other sections included in the complete switchboard. It is intended that the switchboard sections are installed in the order identified by the listing marks, from left to right.


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