Underwriters Laboratories

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Underwriters Laboratories (Inc.) is a well-known testing laboratory that develops standards and test procedures for materials, components, assemblies, tools, equipment and procedures, chiefly dealing with product safety and utility.

UL does not "approve" any product. Rather it tests product samples and permits acceptable products to carry the UL certification mark, as long as they remain in conformity with the standards and with the samples tested to those standards. Placing the mark on untested products would be a type of trademark infringement and violate the UL license to the manufacturer. UL maintains a list of over 100,000 products it has tested and that database is available online to the public.

A product with Underwriters Laboratories listing is said to be "UL Listed." Purchasers can identify such products by the distinctive UL Mark [1]. The company's "file number" may be on the label (typically a letter followed by 5 or 6 numbers (ie E12345)). The "UL File number" can be used to look up a certificate at the UL web page.

A manufacturer of a listed product must demonstrate compliance of its design with the appropriate UL standards, and then demonstrate that it has a program to ensure that each copy of the product will similarly meet the essential criteria. If a product design is modified, a representative example may need to be re-tested before the UL mark can be attached to the new product or packaging. In some cases a component may be "UL recognized", meaning UL has found it acceptable for use in a product that will be tested for UL listing.

UL has ratings standards for hundreds of types of components and products, even bullet-proof vests. The average householder may be more familiar with UL-rated products such as home electrical appliances. A typical standard for electronic products includes not only requirements for electrical safety, but also fire spread and mechanical hazards (such as sharp or moving parts or tipping over). Just because a product has a UL listing does not mean the product will perform acceptably or that it is safe under all conditions.

A UL mark is a representation but not a guarantee that a marked product conforms to the corresponding UL standard. Installing or selling a product without a UL mark (or equivalent from another recognized) may be considered gross negligence in some circles, and may violate insurance requirements or local regulations, meaning the insurance may not have to cover any damages or that the violator may have to pay a fine. A licensed professional may lose his or her license for failure to use materials marked with a UL (or equivalent) label, where required.

In the past twenty years great strides have been made in harmonizing international safety standards, and now the UL mark has attained reciprocity with some other national testing laboratories (i.e., the standards are similar and the tests are similar). The label for products certified for both Canadian and U.S.A. includes "C" and "US Listed" below the UL logo.

A moderately famous video clip shows UL researchers demonstrating the risks of certain models of deep-fat turkey fryer. This serves as a suggestion of the importance of this sort of product testing. [2]

The European analog of the UL mark is the CE mark.

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