UL certification is issued by an NRTL (National Recognized Testing Laboratory). Certification certifies that a product conforms to a particular standard and has value in the United States. In Europe it is commonly known as “UL” because it is often referred to as “UL” standards, but actually Underwriters Laboratories (UL) is just one among many NRTLs, and UL standards are not the only reference standards.
Certifications can be made not only with UL standards, but also with ASME, IEEE, ISA, NEMA standards, NFPA etc. After certifying a product, the NRTL authorizes the manufacturer to affix a registered trademark to it. When a product bears a certification mark, it means that the NRTL has tested and certified the product and that it complies with the requirements of one or more standards.
Nationally Recognized Testing Laboratory (NRTL)
In the United States, NRTLs are qualified private organizations (often also called Third Party Laboratories, third-party or independent) accredited by OSHA (Occupational Safety & Health Administration – agency federal Department of Labor) under the NRTL program to perform independent product safety testing and certification as required by the Code of Federal Regulation (CFR – code of footprints enacted by the Executive and Federal Agencies of the United States of America) Title 29 Part 19010. Each NRTL affixes its own registered trademark, so certification marks differ depending on the NRTL. The list of recognized NRTLs and the standards for which they are authorized to issue certifications can be found on OSHA’s website. UL is one of several NRTLs in the United States. Other examples of NRTLs include Intertek, TÜV SÜD America, TÜV Rheinland, MET Laboratories, Nemko and CSA. In Canada, certification bodies are accredited by the Standards Council of Canada (SCC).
The National Electrical Manufacturers Association (NEMA) is a Washington, D.C.-based U.S. regulatory body that drafts technical standards but does not test products or issue certifications. The following classification of protection categories according to NEMA is mainly concerned with the protection of people from the accidental contacts with parts of the equipment and protection from external influences on the control cabinet.
|Degree of protection
|Indoor installation: protection against dirt (vertical drop)
|Indoor installation: protection against dirt (vertical drop), water drops
|Outdoor installation: protection against rain, sleet and wind-blown dust; also protection against damage due to external ice formation on the control cabinet.
|Outdoor installation: protection against rain, sleet, also protection from damage due to external ice formation on the control cabinet.
|Indoor or outdoor installation: protection against rain, sleet, and windblown dust; in addition, the external mechanical parts are ready for use despite ice formation.
|Indoor or outdoor installation: protection against dust brought by wind, rain, splashes and water jets; also protection from damage due to external ice formation on the control cabinet.
|Indoor or outdoor installation: protection against dust brought by wind, rain, splashes and jets of water, corrosion; also protection from damage due to external ice formation on the control cabinet.
|Indoor installation: protection against dirt (vertical drop), settling suspended dust and drops of non-corrosive liquids.
|Indoor or outdoor installation: protection from dirt (vertical drop), direct water, water entry during partial immersion in limited depth; protection from damage due to external ice formation on the control cabinet.
|Indoor or outdoor installation: protection from water jets and water ingress during prolonged immersion in limited depth; protection from damage due to external ice formation on the control cabinet.
|Indoor installation: protection against dirt (vertical drop), swirls of dust and drops of non-corrosive liquids.
|Indoor installation: protection against dust, dirt (vertical drop), water and oil splashes, and non-corrosive refrigerants.
|The most common UL Marks
|The UL Listing Certification Mark is one of the most commonly used UL Marks. If a product has this mark, it means that UL has verified that a representative sample met UL's safety requirements and that the manufacturer claims that the product continues to meet those requirements. These requirements are based on safety standards published by UL itself. This brand is found on home appliances, computers, boilers, heating systems, fuses, electrical panels, smoke detectors, fire extinguishers, sprinklers, life jackets, bulletproof glass, and on thousands of other finished products.
|Consumers rarely see the UL Recognised Component Mark because it is used for components that are part of a larger product or system. These components can be unfinished products. This brand is found on switches, power supplies, printed circuit boards, industrial control devices and thousands of other components. Given that a recognized component is an incomplete product, its use has conditions of acceptability.
|The UL Classification Mark appears on products that UL has evaluated for specific properties, a limited set of risks, or suitability for use under special conditions. Typical products classified by UL are building materials and industrial equipment, wetsuits' immersion, fire doors, protective equipment for firefighting personnel and industrial vehicles.
|Special marks for each requirement
|The UL Functional Safety Mark appears on products that have been evaluated for the UL Listing Mark and for functional safety, Functional safety is that part of safety that depends on the proper operation of control systems and software with safety functions. Adoption of the Functional Safety Mark is normally limited to products that will be used in a functional safety application.
|Field Evaluations: this label applies to a product that has been fully evaluated in the field rather than in UL laboratories or at the manufacturer's facilities. If a product has undergone significant changes since its manufacture or if it has not received a certification mark from a third-party agency, a building owner, regulatory body, or anyone else directly involved with the product may request UL to evaluate that specific item in the field.