What is UL Certification?
Underwriters Laboratories is a global safety organization that does more than develop standards. It also tests and certifies components such as gaskets and larger products such as enclosures. In addition, UL approves independent laboratories that perform tests according to UL standards.
Manufacturers may say that a rubber product “meets UL standards”, but that doesn’t mean the product is UL certified. UL certified rubber undergoes an application and testing process before receiving a UL Mark and UL Yellow Card, if all requirements are met.
Application and Testing
Typically, it’s the manufacturer of a rubber product that applies for UL certification. The application requires detailed product information, including material specifications and intended use. The product is then tested by Underwriters’ Laboratories or by an independent laboratory that belongs to UL’s Data Acceptance Program.
UL Marks
If the rubber product meets the UL standard, it receives a component-level mark. This symbol proves that it’s UL certified.
More specifically, the UL mark for a rubber product means that it’s UL Recognized.
That’s important to understand because there’s a difference between a product that’s UL Listed and a product that’s UL Recognized.
- UL Listed applies to whole products (such as enclosures) that contain various components and are meant to be used independently, such as for housing electrical equipment.
- UL Recognized is for components (such as rubber) that are a meant to be incorporated into this larger whole.
If you’re designing an enclosure, do you need more than “UL rubber” to meet project requirements? After all, using a UL Recognized rubber product won’t make the entire enclosure UL Listed. There’s separate testing and approvals required at the enclosure level.
UL Yellow Cards
When polymeric materials (such as rubber) receive a UL Recognized Component Mark, they also receive a Yellow Card that lists product information.
The physical version of the card is yellow in color, but term “Yellow Card” also applies to digital versions. Engineers can find Yellow Cards in the UL Prospector® database, or by requesting this information from the manufacturer.
Audits and modifications
UL certification isn’t an endpoint. That’s because UL also conducts periodic surveillance audits and testing to ensure continued compliance with its standards. The company that submitted the original application pays for these audits, which are typically performed twice a year.
If a UL certified product undergoes modifications, these changes must be approved by UL and the product must be re-evaluated. This is designed to prevent manufacturers from making misleading claims about safety and performance. It’s also why the UL mark is so highly trusted.
What is UL 50E Rubber?
UL50E is a standard that extends UL50 by adding specific environmental protections. UL50, the base standard, covers general-purpose electrical enclosures for indoor or outdoor use. It accounts for fire, electrical, and mechanical hazards, but that may not be enough for some applications.
UL50E’s additional requirements make it suitable for outdoor enclosures like battery energy storage systems (BESS) and the junction boxes used in 5G telecommunications. UL 50E enclosures are also used in demanding indoor environments like metalworking facilities.
What is UL 94 Rubber?
UL94 defines fire tests for polymers, a category of materials that includes rubber and plastic. UL 94 contains various flame ratings, each of which has its own test procedure. Within UL 94, there are vertical and horizontal burn ratings for rubber that’s used in electrical and electronic enclosures.
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