Listed Equipment Has Been Tested by a Recognized Lab; Labeled Equipment Carries That Lab’s Mark

Quick Answer

Under IRC 2024 Section R202, “listed” means equipment, materials, products, or services included in a list published by an organization acceptable to the building official and concerned with evaluation of products or services, and whose listing states that either the equipment, material, product, or service meets approved standards or has been tested and found suitable for a specified purpose. “Labeled” means equipment, materials, installations, or products to which a label, symbol, or other identifying mark has been attached by the manufacturer indicating that the equipment, material, product, or installation has been evaluated by a listing organization and found to comply with specified requirements or tested and found suitable for a specified use.

In plain English: listed means independently tested and included in a published database. Labeled means the physical product carries the testing lab’s mark to prove it. The two concepts work together. A listed product should also be labeled so that an inspector in the field can verify compliance without having to look it up in a database every time. When the IRC requires “listed and labeled” equipment, it is requiring both: third-party testing certification and a visible mark on the product itself.

What IRC 2024 Actually Requires

The IRC uses the phrase “listed and labeled” extensively throughout its chapters on mechanical, plumbing, fuel gas, and electrical equipment. Section R102.7 states that equipment and appliances shall be listed and labeled for the application in which they are used. This is a blanket rule that applies wherever the code mandates listed-and-labeled compliance, unless the building official specifically approves an alternate method under the alternate materials provisions.

The testing organization must be acceptable to the building official. In practice, nationally recognized testing laboratories (NRTLs) recognized by OSHA—including Underwriters Laboratories (UL), Electrical Testing Laboratories (ETL, now part of Intertek), CSA Group (formerly Canadian Standards Association), FM Approvals, and several others—are universally accepted by building officials across IRC jurisdictions. Products listed by these organizations and carrying their certification marks satisfy the listed-and-labeled requirement.

The listing must also be for the specific application in which the product is used. A gas appliance listed for indoor use is not listed for outdoor use. A circuit breaker listed for a specific panel manufacturer’s enclosure is not listed for use in a different manufacturer’s panel without a separate listing covering that combination. A range hood listed for use with a specific maximum duct length is not listed for an installation that exceeds that length. The scope of the listing matters, not just the presence of a listing mark.

Installation instructions for listed equipment are part of the listing. Under IRC R303.4 (and equivalent provisions in the mechanical and fuel gas chapters), listed appliances must be installed in accordance with the manufacturer’s installation instructions. Those instructions were part of the testing evaluation and define the conditions under which the equipment performs as tested. Deviating from the installation instructions is effectively deviating from the listed condition, even if the listing mark is still on the product.

Why This Rule Exists

The listed-and-labeled requirement exists because the code cannot test every product in every installation. The IRC sets performance standards, but verifying that a specific water heater, furnace, panel board, or gas valve meets those standards in every individual installation would be impossible for building departments with limited resources. Third-party listing organizations solve this problem by performing the testing before the product reaches the field and publishing the results in a way that building officials can rely on.

The system transfers the evaluation burden to organizations that have the equipment, expertise, and resources to test products systematically. UL, for example, maintains testing facilities capable of subjecting electrical equipment to fault conditions, overloads, arc events, and environmental exposures that no building inspector could replicate during a routine field inspection. When a product passes those tests and receives a UL listing, the building inspector can rely on that listing as evidence of compliance without re-testing every unit in the field.

The label on the product is the field-verifiable evidence of the listing. An inspector who cannot carry a listing database to every inspection can look for the UL, ETL, CSA, or FM mark on the equipment and immediately know that the product has been independently evaluated. Without the label, the listing is harder to verify in the field and provides weaker assurance of compliance. Without the listing, the label is just a sticker that means nothing. The two together create a reliable, field-verifiable compliance system.

What the Inspector Checks at Rough and Final

At rough inspection for electrical work, the inspector checks that the electrical panel is a listed panelboard from a recognized manufacturer, that circuit breakers are listed for use in that specific panel (breakers and panels from different manufacturers are often not cross-listed), and that junction boxes, cable connectors, and other enclosures carry listing marks appropriate for their application. Romex cable, conduit fittings, wire nuts, and AFCI and GFCI devices all have listing requirements that inspectors verify by looking for the UL or equivalent mark.

For mechanical rough inspections, the inspector looks for listing marks on gas appliances, water heaters, furnaces, and heat pumps. The listing label typically includes the model number, the listing organization’s mark, and sometimes the specific conditions of the listing (indoor use only, vent type required, clearance requirements, etc.). Inspectors compare the label information against the installation to verify that the application matches the listed conditions.

At final inspection, the listed-and-labeled check extends to the complete installed system. Electrical devices in outlet boxes, light fixtures, exhaust fans, and appliances all carry listing marks that the inspector can verify visually. Any equipment that was substituted from the approved specifications during construction and that lacks appropriate listing marks may be flagged for replacement. The inspector is not expected to research every product in a listing database, but obvious absence of marking—particularly on appliances, electrical panels, and safety devices—is a clear red flag.

What Contractors Need to Know

Contractors must verify listing applicability, not just listing existence. A product may carry a UL mark but not be listed for the specific application the contractor intends. This is most common with electrical equipment. A circuit breaker carries a UL listing, but if it is not listed for the specific panel it is installed in, the installation violates the listed-and-labeled requirement. Many panel manufacturers produce panels that are only listed with their own brand of breakers, and mixing brands creates an unlisted installation even if both the panel and the breaker individually carry listing marks.

The same principle applies to gas appliances with venting. A gas water heater listed for use with a specific Type B vent system is not listed for use with a different vent material, diameter, or configuration. Contractors who improvise on vent materials, connector types, or vent run lengths beyond the installation instructions are creating an unlisted installation that violates the code and may create a serious carbon monoxide risk.

Contractors should also preserve the listing marks and installation instructions for any equipment they install. Inspectors may ask to see installation instructions to verify that the installation complies with the conditions of the listing. Documents that are thrown away before inspection create unnecessary friction. Keeping a job file with installation instructions for every listed appliance and device is good practice that makes final inspections faster and smoother.

Unlisted electrical components from overseas suppliers are a growing problem in residential construction. Products purchased through online marketplaces or specialty importers may carry counterfeit listing marks or marks from testing organizations not recognized by the building official. Inspectors are increasingly aware of this issue and may scrutinize listing marks that do not appear to be authentic UL, ETL, CSA, or FM marks. Using products from established domestic or recognized import supply chains, verifiable through the listing organization’s online product directory, is the safest approach.

What Homeowners Get Wrong

Homeowners frequently assume that any product sold at a major home improvement retailer in the United States is automatically listed and labeled for all residential uses. This is not always true. Some products—decorative light fixtures imported directly from manufacturers, smart home devices with uncertified electrical components, outdoor extension cords used as permanent wiring, and similar items—may not carry appropriate listing marks or may be listed for a different application than the homeowner intends.

Homeowners doing DIY electrical or plumbing work also sometimes use components that are not listed for residential applications. Industrial or commercial components, even if technically functional, may not be listed for the code-compliant use the homeowner intends. An inspector who sees unlisted components in a DIY electrical project can require removal and replacement regardless of whether the component appears to be working correctly. Functionality is not a substitute for listing compliance.

A third common mistake is assuming that a product that was listed at the time of purchase remains listed at the time of installation or inspection. Listing organizations can delist products that fail ongoing surveillance testing or that are found to have manufacturing defects. Checking the listing organization’s current online product directory for products that have been sitting in storage for an extended period is a reasonable precaution for high-stakes electrical or gas equipment.

State and Local Amendments

The listed-and-labeled requirement is part of the model IRC and is generally adopted without significant local amendment. However, some jurisdictions require listing by a specific organization or recognize additional testing organizations beyond the standard NRTLs. California’s Title 24 energy code, for example, has its own certification program for energy-regulated appliances that operates alongside (and sometimes overlaps with) the IRC listed-and-labeled requirement. An appliance that is listed by UL may still need separate California Energy Commission (CEC) certification to be lawfully installed in California.

Some jurisdictions also have local requirements for specific types of equipment. Seismic strapping requirements for water heaters in California, radon-resistant features in certain high-radon areas, and specific listing requirements for wood-burning appliances in air-quality-sensitive zones are examples of local amendments that interact with the base IRC listed-and-labeled framework. Contractors working across multiple jurisdictions need to maintain awareness of these local variations.

The recognition of testing laboratories may also vary slightly between jurisdictions. The building official has discretion to accept or reject listing organizations. In practice, all major NRTLs recognized by OSHA are accepted in virtually all IRC jurisdictions, but obscure or foreign testing organizations without OSHA NRTL recognition may not be accepted. When using products listed by less familiar testing organizations, verifying acceptance with the building official before installation is prudent.

When to Hire a Professional

Hire a licensed electrician or licensed plumber for any work where listed-and-labeled compliance is required and where the correct listing for the application is not obvious. The listing applicability question—is this product listed for this specific use in this specific configuration?—requires familiarity with listing databases, product specifications, and the conditions attached to each listing. Licensed trade professionals with current field experience know which products are commonly accepted in their jurisdiction and which products create inspection problems.

For specialty equipment—custom-built electrical assemblies, imported appliances, or equipment modified from its listed configuration—a licensed engineer may need to evaluate the installation and prepare a technical letter supporting approval of the equipment under the building official’s alternate materials authority. This is the appropriate path for equipment that cannot satisfy the standard listed-and-labeled requirement through conventional means.

Common Violations Found at Inspection

• Circuit breakers from one manufacturer installed in a panelboard from a different manufacturer without a cross-listing that authorizes that combination
• Electrical devices—outlets, switches, fixtures—carrying counterfeit or unrecognized listing marks purchased through online marketplaces
• Gas appliances installed with venting materials, configurations, or run lengths that exceed the installation instructions included with the listing
• Water heaters lacking required ANSI or CSA listing marks appropriate for the fuel type and installation location
• Smart home electrical devices with integrated components that do not carry individual listing marks for each electrical function
• Outdoor extension cords used as permanent wiring, which are not listed for permanent installation regardless of their listed rating for portable use
• HVAC equipment installed in applications that exceed the listed conditions—for example, refrigerant type, operating pressure range, or outdoor temperature rating—in violation of the manufacturer’s installation instructions and the conditions of the listing