Occasionally, we receive questions from customers asking why a part’s labeling or other materials do not include a visible ‘UL94V-0’ mark, or where the UL documentation for a product marked as UL94V-0 compliant is on the assumption that this compliance means the part is “UL rated”. How are these different UL listings, ratings and standards related?
The UL 94 Plastics Flammability Standard was created by Underwriter’s Laboratory, but it is not analogous to the organization’s Rating or Recognition work and has no real relation to that work. UL94 is instead a standalone standard that manufacturers can test for and adhere to on their own, without any intervention or testing from UL.
As UL94 is a materials-based standard that applies to base plastic materials rather than finished product assemblies, the industry generally does not consider it necessary to include stamps or documentation on products that use UL94-rated materials, though some choose to do so anyways. This is why you’ll sometimes see UL94 stamps in plastic components, such as connector housings. This is not considered mandatory.
For more information on what customers typically mean when they ask if a product is UL listed or recognized, check out Understanding UL, When is it Applicable? here on TechForum.