Is it permitted to replace a sign face on a listed sign?

Question: Electric signs

Is it permitted to replace a sign face on a listed sign?



This question was addressed in the March/April UL Question Corner column and since the publication, UL received a number of follow-up questions regarding this issue. It should be noted that UL 48, the Standard for Electric Signs anticipates that sign faces may likely be changed from time to time due to commercial changes in product and property ownership as well as damage that may occur to sign faces.

Depending on the design and the location of the sign, either dry or wet location, a sign face may provide more than one function. In some cases the sign face may be a weather shield keeping water off of current-carrying parts inside the sign. In other cases, it may be both a weather shield and an electrical enclosure. For either situation, the sign face may be replaced, but care must be taken to make sure a proper sign face material and installation procedures are being used.

A question sometimes asked is whether replacing the sign face will void the UL Listing. The UL Listing refers to compliance of the product with the applicable UL requirements when the product leaves the factory under UL Follow-Up service and when it is installed in accordance with the manufacturer’s installation instructions. Replacing the sign face on a Listed sign is similar to the servicing of any electrical product after it has been installed in the field.

Those servicing the product, or in this case replacing the sign face, have the responsibility of assuring that the serviced product continues to comply with UL requirements.

When replacing a sign face it is critical to determine if the sign face serves as part of an electrical enclosure for live parts. This can be determined by noting the marking on the sign. Since it is critical that sign faces serving as electrical enclosures are constructed of materials that meet the enclosure requirements of UL 48, the Standard for Electric Signs requires this type of sign to be marked with the following:

1. “Do not attempt to repair or service a damaged sign face, cable support, or high-voltage splice insulator. For servicing of this sign, contact ____________.” (Blank to be replaced by the sign manufacture’s company name, city and state.)

2. “Replace only with ______ __, Type ________.” (Blanks to be replaced by sign manufacturer’s company name and material type or designation.)

3. “Danger — High Voltage — Disconnect Power Before Servicing.”

When encountering a sign with these markings, it is important for service organizations to use only the sign face material specified. This can be determined by contacting the sign manufacturer marked on the sign (see item 1 above).

Signs that are not marked as indicated above, do not have a sign face that acts as an electrical enclosure. Replacing a sign face on all other signs in which the sign face does not serve as an electrical enclosure does not require the use of a specific sign face material. However, it is expected that it be replaced in a workmanship like manner taking care not to damage internal components or insulation, use a sign face of the appropriate size, and use appropriate hardware to adequately secure and seal replacement sign face such that the sign continues to comply with the UL requirements.

When a sign has been serviced in the fi eld and compliance to UL’s requirements needs to be confirmed by UL, the company performing the servicing may contact UL to conduct a Field Evaluation. A Field Evaluation can be initiated by calling 1-877-UL Helps (854-3577). More information on fi eld evaluations can be also obtained online at As previously stated, UL has a documented policy on field modification of Listed products that can be found on the Regulator page at:

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