UL Listed

UL Listed

Testing and certification of safety of products in many countries is conducted by national agencies, organizations or companies. Underwriters Laboratories (UL) is an organization with its headquarters in the United States. They offer services such as testing and certification of products. If the testing is successful the manufacturer is allowed to indicate this with a test mark such as UL Listed. The test mark UL Listed has is highly valued for sale, insurance coverage and implementation in buildings.

Underwriters Laboratories develops and publishes safety standards. They are basis for safety requirements according to which products are tested by Underwriters Laboratories.

OSHA - The Connection of UL Listed and Work Safety Laws

OSHA (Occupational Safety & Health Administration) is a US Federal Agency and is subordinate to the US Department of Labor. By enforcement of standards and other measures they create a safe work environment. OHSA certifies testing organizations such as Underwriters Laboratories and therefore gives permission to test and certify products in accordance to test standards for the US market. Institutions certified by OSHA for this purpose are called NRTL (Nationally Recognized Testing Laboratories).

UL Listed for Canada and USA

CSA (Canadian Standards Association) is the Canadian equivalent to Underwriters Laboratories as a test institution for product certification. Underwriters Laboratories and CSA work together. Products can have test labels which are valid for US as well as the Canadian market. The test labels of Underwriters Laboratories for the shared market are indicated by cULus and cURus.

What does UL listed mean?

Underwriters Laboratories hands out a number of test labels which document different purposes and tests. The most important test labels are "UL Listed" and "UL Recognized". UL Listed is used for products which can be used autonomously. UL Recognized is used as a test label for components which are used in products and not used as an autonomous product.

An example for a product with a UL Listed test label which can be used autonomously is an external power supply which can be used by itself to fulfil its purpose of charging a battery. An example for a component which can only be used in combination with other components is an industrial socket which is intended for use in a control cabinet and has a Recognized certification (cURus). There are also products which have a certification in accordance to UL Listed and UL Recognized. The test certification indicates for which application and environmental conditions the test label was handed out.

What is the UL standard?

Underwriters Laboratories develop technical standards for different applications in the industry, based on their long term experience. For the development of nationally valid standards Underwriters Laboratories is verified by ANSI (American National Standards Institute) in the USA and SCC (Standards Council of Canada) in Canada. The standards developed by Underwriters Laboratories can be found on their website. Underwriters Laboratories has developed over 1500 standards.

For some specific industrial applications standards of Underwriters Laboratories are determining factors to receive a certification. The central standard for control cabinet engineering is UL 508A. UL 1741 is used for testing of inverters. Contactors and engine starters are tested in accordance to UL/IEC 60947-4-1. This is a harmonized standard.

UL Listed - Harmonization of Standards

For a lot of manufacturers in automation technology as well as machine and plant engineering the access to global markets is key for expansion of the company. Global sale of products is simplified by harmonization of locally valid standards. In past years Underwriters Laboratories and IEC worked together on different joint standards and helped the advancement of harmonization. An example is UL 61010-2-201 and its European equivalent IEC 61010-2-201 which is the standard for control and managing units (SPS).

The term "UL Listed" is a registered trademark (see United States Patent and Trademark Office - Trademarks & Trademark Electronic Search System (TESS) Register)