OSHA the Occupational Safety and Health Administration, the US government’s enforcement arm for safety and health issues has been tasked with overseeing professional independent testing laboratories. The best known of all independent testing laboratories is Underwriters Laboratories, UL.

UL was established by insurance underwriters to find ways to reduce unsafe hazards in the marketplace, thereby reducing dramatic insurance claims. Since its inception, UL has, been involved with writing standards of safety acceptability in the United States. They have been one of the premier developers of safety standards but they have not been the only group to write standards. Groups like NEMA, IEEE, and ANSI have also contributed to the development of standards. Similarly UL is not the only independent testing laboratory.

OSHA has become the certification agency for independent testing laboratories in the United States. A group of engineers who decide to do testing as a business must qualify through OSHA to function as an independent test facility. Further-more, they must show competence in specific areas, fire testing, for instance. Once they have demonstrated competence in the area of fire testing and have shown that they possess the facilities and equipment to do fire testing, OSHA will certify them as a Nationally Recognized Testing Laboratory (NRTL) to do fire testing. Factory Mutual, FM, is one such NRTL for fire testing, Southwest Laboratories is another.

Many independent testing laboratories have NRTL status. Most are relatively specialized and limited in their scope. The three major testing laboratories that operate in the United
states that have a wide scope of testing qualification are, UL, CSA, and ETL. They are certified by OSHA as NRTLs.

NRTL status tells all customers that the services performed by these companies, to list or to label products, is reliable and legally binding throughout the United States. ETL, originally known as Edison Testing Laboratories, is an old, respected, nationwide testing group with credibility equal to UL or CSA. Therefore an ETL listing label is legally binding nationwide and should instill equal consumer confidence in the manufacturer that they have cared enough to submit their products to the rigorous safety compliance process and achieved the right to apply a Nationally Recognized Testing Laboratory label that certifies compliance assurance.