What are Nationally Recognised Test Laboratories (NRTL) and why are they important?


Brainboxes are frequently asked for products which are “UL Certified”, this article aims to clarify what UL certification is and how this applies to Brainboxes products.

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What is an NRTL?

A Nationally Recognised Test Laboratory (NRTL) is the official name given to a group of independent, non-government organisations, officially recognised by the United States Government, Occupational Safety and Health Administration (OSHA), under Federal Code 29 CFR 1910.7.

At the time of writing, OSHA officially recognises 18 individual test laboratories under the NRTL group. Each of these laboratories perform testing and certification to safety standards developed by institutions such as, the American National Standards Institute (ANSI) and Underwriters Laboratories (UL).

A full list of NRTL’s can be seen at the following link: https://www.osha.gov/nationally-recognized-testing-laboratory-program/current-list-of-nrtls

Why is NRTL Certification important?

As with any product, testing and certification is vital and NRTL certification is no different. There are numerous reasons why NRTL certification is important; first and foremost, it highlights that a product has been thoroughly tested to the relevant standards by an external test house. This validates the product and ensures it is safe for distribution into the United States.

Furthermore, it provides clear certification that an electrical or electronic product complies with the standards required for the U.S. Market. Many retailers and distributors will refuse to stock a product if insufficient evidence is provided to show that NRTL certification has been achieved. NRTL certification gives license for a product to be distributed quickly into the vast U.S. Market.

Failure to provide sufficient evidence that a product has been tested can result in fines.

What does the term ‘UL Certified’ mean?

Much of the confusion surrounding a product being NRTL certified, stems from the term ‘UL Certified’ being used synonymously to describe a product which has been tested and approved by an NRTL. This comes as Underwriters Laboratories (UL), were previously the only source of testing and approval within the United States.

Following legal action, it was deemed that other test houses should also be able to conduct this testing and that their certification should be seen as equal throughout the United States. The resulting outcome saw OSHA create the aforementioned group of NRTL’s. Underwriters Laboratories, now a recognised NRTL, still share the name with the industry standard.

A manufacturer can send their product for testing and certification to any of the approved NRTL’s. The chosen test house will perform testing outlined by the industry defined standards for that product type, as developed by ANSI & UL, with their product receiving equal certification should it pass these tests.

Devices which are tested and certified by an OSHA recognised NRTL are deemed to comply with the regulations required for its sale and distribution into the United States Marketplace.

Are manufacturers required to display the UL mark?

While Underwriters Laboratories (UL) are responsible for writing many of the official standards, they are only 1 of the aforementioned 18 recognised NRTL’s for testing and certification. Legally, the requirement is that the laboratory which performs the testing should be an NRTL recognised by OSHA. The certified product can then physically apply the respective NRTL’s mark to show certification.

Eurofins MET Labs

Brainboxes uses the NRTL Eurofins MET Labs for our product testing and certification.

Eurofins MET Labs (formerly MET Labs) are a recognised NRTL, who following the creation of the NRTL group, where the first organisation to be officially recognised as an NRTL by OSHA in 1989. Products featuring the MET mark, symbolise compliance to the respective UL/CSA standards for the type of product and indicate compliance to required standards by virtue of Eurofins’ equivalent NRTL accreditations to UL, within the regulations of the United States and Canadian Markets.

The MET mark is 100% equivalent to the UL mark, both of which are recognised in law by the United States Government. Both marks indicate conformance to NRTL standards.

Please see the following link for further information on the MET mark: https://metlabs.com/services/product-safety-testing/met-vs-ul/ 

The MET mark displayed on a product can take a number of forms; the basic symbol features ‘MET’ in a circle, accompanied by either a ‘C’, a ‘US’ or both depending on the testing which has been performed on the product. The additional ‘C’ or ‘US’ designates the market which in which the product has been tested and certified for, with ‘C’ being for the Canadian Market and ‘US’ being the United States Market. Optionally, the MET mark may also specify the specific standard to which the product is certified. Further below, is an example of the MET mark used on the Brainboxes products.

Please see the following article from Eurofins on the MET mark: https://www.eurofins.com/electrical-and-electronics/about-us/certifications/eurofins-met-mark/

Are Brainboxes products NRTL certified?

While all Brainboxes manufactured products are thoroughly and vigorously tested, they are not all NRTL certified.

Our Ethernet to Serial (ES), Ethernet to Digital (ED) and Network Switch (SW) product ranges have all been NRTL certified to the UL standard UL-62368-1, for safety and issued with the MET mark for validation. Internationally, this standard is also known as IEC62368-1 & EN62368-1.

The below list of products are UL certified and allows the use of the MET mark as also shown below:


ES-020 ES-511 ED-004 ED-516 SW-005 SW-525
ES-246 ES-522 ED-008 ED-527 SW-008 SW-505XX
ES-257 ES-551 ED-038 ED-538 SW-015 SW-508XX
ES-320 ES-571 ED-204 ED-549 SW-104 SW-515XX
ES-313 ED-560 SW-105 SW-605XX
ES-357 ED-582 SW-108 SW-608XX
ES-413 ED-588 SW-115 SW-615XX
ES-420 ED-593 SW-125 SW-705
ES-446 SW-504 SW-708
ES-457 SW-504 SW-715
SW-508 SW-725
‘XX’ denotes a variant of the product


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