In a page on its website, Underwriters Laboratories (UL) explains the appearance and significance of its many marks. Included on that page, and potentially of particular interest to professionals in the structured cabling industry, are UL's Listed, Classified and Verified marks.
Here, we excerpt parts of UL's explanations of the three marks.
UL Listed Mark - One of the most common UL marks. If a product carries this mark, it means UL found that representative product samples met UL's safety requirements. These requirements are primarily based on UL's own published standards for safety ... The UL Listing mark appears on end products and complete components suitable for factory and field installation. All of the products carrying a UL Listing mark are covered by UL's Follow-Up Service program to verify that they continue to be manufactured in compliance with UL's safety requirements. A UL Listing marking appearing on a product typically consists of four required elements: 1) "UL in a circle" symbol, 2) The word "Listed," 3) Product name or company name/file number, 4) Issue/serial number or alphanumeric control number
UL Classified Mark - Appears on representative samples of products that UL has evaluated by only with respect to specific properties, a limited range of hazards, or suitability for use under limited or special conditions. Typically, products Classified by UL fall into the general categories of building materials and industrial equipment. In the Classification service, UL determines that a manufacturer has demonstrated the ability to produce a product complying with UL's requirements with respect to one or more of the following: 1) Specific risk, e.g. casualty, fire, etc., 2) Performance under specific conditions, 3) Compliance with regulatory codes, 4) Compliance with specific standards such as international standards, 5) Other conditions as determined by UL. All products carrying the UL Classified mark are covered by UL's Follow-Up Services program. A UL Classified mark that appears on a product typically consists of four required elements: 1) "UL in a circle" symbol, 2) The word "Classified," 3) Product name or company name/file number, 4) Issue/serial number or alphanumeric control number
UL Performance Verified Mark - Specific to communications cable, this mark can be applied to UL Listed communications cable, to performance standards such as ISO/IEC 11801 and NEMA WC66. It can also be applied to Listed fiber-optic cable verified to Telcordia specifications. The UL Verified Performance mark may also be applied to data-transmission or optical-fiber cable verified to performance specifications only. The Performance Verified mark signifies that telecommunications cabling products are certified to both safety (Listed) and performance (Verified), and comply with industry standards and draft standards.
When UL introduced its Performance Verified mark, it established a list of frequently-asked-questions, aimed at manufacturers of communications cable that may see benefit in obtaining the mark for their products. In that FAQ, UL addressed the question, "What are Listing and Verification Marks and how are they different?" Its answer: "The UL Listing Mark on a product means that UL has tested and evaluated representative samples of that product and determined that they meet the requirements of UL standards for safety, such as fire propagation, shock, etc. Products bearing a Verification Mark have been investigated by UL to an industry performance standard, such as TIA. All UL Marks are registered certification Marks of UL, and may only be used on or in connection with products certified by UL under the terms of written agreement with UL."
Related story: UL requires holographic labels for communications cable