OSHA recognized laboratories conduct their tests against the same sets of U.S. standards and codes, regardless of who authors or publishes them. NRTL's test products to U.S. standards, including ANSI, UL, CSA, NSF, and many others. An NRTL is an organization that OSHA has "recognized" as meeting the legal requirements in 29 CFR 1910.7. The recognition is an acknowledgement that an organization has the necessary qualifications to perform safety testing and certification of the specific products covered within its scope of recognition. As a result, OSHA can accept products "properly certified" by the NRTL which means:
1) The product is labeled or marked with the registered certification mark of the NRTL.
2) The NRTL issues the certification for a product covered within the scope of a test standard for which OSHA has recognized it.
3) The NRTL issues the certification from one of its sites (i.e., locations) that OSHA has recognized. Below is a link to OSHA's current list of NRTL's which includes UL, CSA, ETL, etc. https://www.osha.gov/dts/otpca/nrtl/nrtllist.html
In the eyes of OSHA and the US Government, all NRTL's are considered equal and a product certified by any one of the recognized NRTL's should be accepted by an Authority Having Jurisdiction (AHJ) on the State level.