Installing UL Certified LED Sign Retrofit Kits- What you should know

Frequently Asked Questions

Sign Retrofit Kits can be used to retrofit Neon tube sign

  • Does retrofitting a sign or luminaire ‘void’ the UL Listing?

Retrofitting an installed sign or luminaire does not impact the original Listing. The Listing Mark is applied
by the OEM as the manufacturers’ attestation that the product met the appropriate UL Standard when it was shipped. However retrofitting a sign by using an unqualified person or by using non-certified kits or components could compromise the safety of the sign and places the full burden for reviewing and approving the modifications onto the authority having jurisdiction.

  • Is a Field Evaluation required for retrofitting?

If the sign is modified using a Certified retrofit kit intended for that type/model of a sign per the installation instructions, then a field evaluation should not be required. A Field Evaluation is appropriate if a sign was converted using a non-certified retrofit kit.

  • Does the authority having jurisdiction (AHJ) need to be notified when a sign is retrofitted?

Many jurisdictions require a permit and AHJ approval. However each jurisdiction or municipality enforces
sign retrofits according to their local adopted regulations.

  • Is it okay for installers to build their own retrofit kit using off the shelf pieces and parts?

No, the NEC requires retrofit kits to be Listed. If an installer or contractor decides to get off-the-shelf pieces and parts, then the sign is no different than any other field-modified equipment and either the AHJ needs to use Section 110.3(A) or require a Field Evaluation.

  • How do I confirm that a sign retrofit kit is UL Certified?

UL Certified Sign retrofit kits are identified by the presence of the UL Certified Mark on the kit’s installation instructions. Up-to-date information about sign retrofit kits, including current certification status can be verified anytime by searching under the category code UYWU on the UL Product iQTM database at, or on the UL iQ™ database for Solid State Lighting at iQ database can be searched parametrically to identify kits that meet specific applications.

  • Is permission from the original sign manufacturer required to retrofit their product?

Installed signs are the responsibility of the owner. The owner makes the decision regarding retrofitting and should understand the installer qualifications necessary to meet the local code requirements. Retrofitting without explicit permission from the sign OEM could eliminate any remaining warranty coverage.

  • What qualifications are required for someone to retrofit a sign?

Jurisdictions vary in their adopted requirements regarding qualifications necessary for modifying installed
equipment. Some areas may require licensed electricians and some allow other means of qualifying retrofit
installers. Contact your local AHJ or planning department to determine the qualifications necessary in your

  • Can a retrofit kit be made by a manufacturer other than the original sign manufacturer?

UL certified retrofit kits can be made by any company. Some sign shops may make retrofit kits specific for their
signs. The installation instructions identify the type of sign for which the kit is intended and should always
be consulted prior to any retrofit decision to determine suitability.

  • Are retrofit kits for specific signs or are they generic?

Retrofits can be either specific for a particular model of a sign or more generic in nature for standardized
constructions like box signs and channel letters.For generic sign kits, the term “General Purpose” will be
included as part of the UL Certified Mark when it is provided on the installation instructions.

  • What is included in a retrofit kit?

UL certified sign retrofit kits always contain a set of detailed Installation instructions which identify the type of sign(s) the kit is suitable for, major kit components, preparation steps, and wiring instructions. Kits include the major components such as LED Driver/Power Supply, LED Modules and mounting means. Kits might also include adhesives, connectors, lampholders, and wire, although these common components may be called out in the installation instructions as installer supplied parts.

  • Where is the retrofit kit certification mark?

In a bulletin to industry dated May 4, 2018 UL announced that effective January 1, 2019 the UL Certified Mark
for sign retrofit kits will be located on the kit’s installation Instructions. The use of the traditional UYWU UL
Classified Mark on sign retrofit kit components will be phased out over time.

  • Why do both the UL Recognized Mark (backwards UR)and the Classification Mark continue to appear on some power supplies?

While UL has announced that the UL Certified Mark on the kit’s installation instructions will become the only
method of labeling UYWU sign retrofit kits, we expect there will be a transition period during which the
Classification Mark on a component may be the only proof of Certification.

  • Can I use UYWU retrofit kits in refrigerated display cases?

UL evaluates LED retrofit kits specifically for commercial refrigerators and freezers under category code IFAS. You can locate Certified LED luminaire conversion kits for commercial refrigerators and freezers by searching under the category code IFAS on the UL Product iQ™ database at, or on the UL iQ™ database for Solid State Lighting database at

  • How do I get UL certification to make retrofit kits?

Contact UL at

  • Who can I contact if I see retrofit kits or products being mis-used in the marketplace or in the field?

Report safety related concerns about UL products to our Market Surveillance team by filing a Product Incident Report. To file a report go to