A UL mark is not an official certification mark and, strictly speaking, is not required if a product is to be sold in the United States. In practice, however, serious complications almost always arise when a product without a UL mark is introduced to the U.S. market. The same applies to the installation of such products in industrial production facilities—and even to the facilities themselves. We explain why the UL mark is so important.
What makes UL certification so important?
Underwriters Laboratories (UL) is a private organization that tests equipment, products, and components for safety in exchange for a fee. UL is one of the few companies in the U.S. that is officially recognized by the Occupational Safety and Health Administration (OSHA) as a testing laboratory (Nationally Recognized Testing Laboratory, or NRTL for short). UL develops its own standards to ensure objective testing. If a product meets the requirements set forth in these standards during testing by UL, it may bear the corresponding UL mark. The UL mark is therefore, first and foremost, a purely private-sector trademark. In practice, it is usually difficult or even impossible to put a system or machine into operation without UL certification. Wholesalers often refuse to include products in their product range that do not bear the UL mark. Many insurance companies in the U.S. also require their customers to use only UL-certified products and components; otherwise, insurance coverage is voided. But where does the authority of the UL mark come from?
UL Markings – A De Facto Standard
Although UL standards are not legally binding, they are closely linked to U.S. occupational safety and product safety laws. For example, the National Electrical Code (NEC) refers to UL standards on multiple occasions, and some revisions to the NEC are even based on UL standards. As a result, UL standards have increasingly become a de facto standard for numerous aspects of product and workplace safety. In recent years, there has also been a growing trend toward the standardization of safety regulations. The importance of UL standards—and, with them, the UL mark—will therefore continue to grow.
UL Marking: Important for Machine and Equipment Manufacturers
However, UL marking is important not only for individual components and products, but also for entire machines and systems. Here, too, while UL marking is generally not required by law, the absence of such marking can still lead to serious problems if at least the control system or the control cabinet—which, according to UL standards, is a significant source of danger—does not bear a UL mark. Why? This is again due to the status of UL standards as de facto standards.
To ensure workplace safety, there are also a large number of laws and regulations in the United States. Unlike in Germany and the rest of the EU , local regulations take precedence over national ones. Accordingly, oversight of all these regulations rests with local authorities (Authorities Having Jurisdiction, AHJ), which appoint one or more inspectors (AHJ Inspectors) for this purpose. No facility may be put into operation without approval from the responsible AHJ inspector. If, on the other hand, the AHJ approves the operation of a facility, it may be held liable in the event of damage.
A UL mark is also invaluable in this area. If a system or part of it—for example, the control cabinet—bears a UL mark, the AHJ inspector can see at a glance that the product complies with the relevant UL standards. However, a UL label from Underwriters Laboratories is not in itself a guarantee of approval, particularly since the relevant AHJ may impose additional requirements; nevertheless, UL marks are recognized throughout the United States.
What types of UL markings are there?
There are a number of certifications issued by UL. The four most important ones are as follows:
UL Listing: This UL certification is available only for complete products. Representative samples are tested to ensure compliance with the applicable UL standards. This UL Listing mark is what is commonly referred to as “UL approval .”
UL classified: This certification also applies to entire products, but is limited to specific characteristics, such as suitability for a defined hazard area. Only under these conditions are the products just as safe as those bearing the UL Listing label.
UL Recognized: This certification process tests individual components rather than products. Only components bearing the UL Recognized Component mark may be incorporated into products that are already UL-certified as a whole, without requiring recertification of the entire product.
Field Inspection: If a product or piece of equipment has been inspected and found to be in compliance at the site of use —rather than at a UL laboratory—UL may issue a corresponding inspection label.
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Are UL markings also valid in Canada?
Manufacturers who wish to market their products throughout North America often wonder whether the UL mark is also valid in Canada or whether retesting in accordance with CSA standards is required there. The answer to this question is clear: If a product or component is certified to UL standards and is authorized to bear the corresponding UL mark, a separate certification for the Canadian market is not required. Certification marks recognized in both the U.S. and Canada feature the letters “C” and “US” (cULus) on the label next to the UL logo.
Zusammenfassung
Although a UL mark is not required by law, any manufacturer wishing to sell its products on the North American market cannot do so without displaying the appropriate label on its products. This is due to the high standing that UL enjoys in the United States. This, in turn, is attributable to the importance of UL standards for U.S. occupational safety and product safety laws.
