“Recognized” or “Listed”?
The Underwriter’s Laboratories (UL) marks and acronyms are numerous. You find them on both components and complete products with various markings. Despite a nearly exhaustive list of marks, three commonly used North American markings are ordered from left to right in the table below. Note: in 1 and 3, the lead testing agencies are reversed.
|
1
|
2
|
3
|
- Products “Listed.” This category is tested by UL to meet U.S. and Canadian standards complete products.
- Components “Recognized.” A category tested by UL to meet standards for components only which can be sold in the U.S. and Canada.
- Products This category tested by CSA to meet U.S. and Canadian standards.
|
 |
 |
 |
Globally, the above marks are a small sampling of markings denoting approvals found on country-specific components and cord sets determined by agencies worldwide. It’s important to note that UL “Listed” and UL “Recognized” are differentiated: listed covers “complete” products (a cord set) while recognized covers components such as a plug. To be either recognized or listed, each component or completed product must meet a specific set of UL standards.
UL “Recognized” Versus “Listed”
The recognized mark focuses on the individual components of a system, not the complete product housing the components, such as an accessory power strip (APS). An APS has among other components at least one inlet, multiple outlets, and a circuit breaker or a fuse—those components must meet UL requirements (standards) to become recognized. The APS can then be submitted to UL for listed status as a complete product if having successfully met UL requirements for an accessory power strip.
One upside for manufacturers making only components is the fewer number of approvals required compared to manufacturers making multiple components as well as complete products—the testing and approval process should be less expensive for recognized products. This does not factor in extremely rare metals which may drastically affect component cost outside of testing. Whether common alloy or rare metals, the UL recognized components are considered “safe” components which add to their value and marketability.
The UL Follow-Up Service requires manufacturers to report quarterly (in certain cases) as well as conducting tests and audits on approved or certified products on a regular schedule to ensure the approved products continue to meet specific standards. If a product carries a UL listed mark, it means it has met UL’s requirements for a complete product.
