The letters UL stand for Underwriters Laboratories Inc., this organisation is an independent institution which is not orientated to success and arranges safety tests and certificates for products.

More than 100 years ago at the beginning of UL they focused on issues in the fire protection area.

Nowadays many products, materials, constructions and systems are tested and judged in view of their electric, fire- and accidental risk.

Furthermore the security against burglary, the ability to detect fire, to control and to prevent it, is analysed.

UL develops safety regulations which are often taken as ANSI norms.

Underwriters Laboratories certificate and register customs according to ISO 9000.

In respect of marking UL licensed products it is differed between Recognized Components and Listed Components:

Recognized Components

This marking is used for products which are not completed in regard to their usage.

  • These products are listed in the “yellow component database”
  • The correct usage of these components effects in respect of the Conditions of Acceptability (COA) in which the basic conditions and application parameters are defined.
  • That can be limitations of the deratings, application-/ usage specifications in combination with further active or passive components, e.g. certain safety models.
  • Furthermore the application area of “branch circuits” or “feeder circuits” of the components is defined in the COAs.

Listed Components
This marking is used for products which can be processed directly by the customer, so they form a completed functional unit.

  • These products are listed in the “green component database”

The usage according to the deratings is possible without any restrictions. Therefore all technical data have to be directly apparent on the label. Special assembly instructions have to be directly assigned at the device or at the product insert of the product.

Products with this sign have an increased acceptance, especially in the international area.

Many customers desire or require an UL certification. The certification grants facilities in questions about product liability and has increased acceptance at authorities.

To guarantee the compliance of the tested goods, there is a follow up service.

A person in charge of UL visits our works frequently and controls areas of our production.

Since the Dr D. Mueller GmbH is an UL recognized repacker the insulating materials processed by our company do not lose their UL certification during processing.