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Modified NRTL-Listed Equipment

What Does Modified NRTL-Listed Equipment Mean?

The term “NRTL-listed equipment” is used to describe any piece of electrical equipment that has been tested by a Nationally Recognized Testing Laboratory (NRTL) and certified as safe for use in the workplace. The designation is specific to America, although other jurisdictions have similar programs. The NRTL program was developed by OSHA, and OSHA remains the organization responsible for deciding whether a laboratory can be approved as an NRTL.

The term “modified NRTL-listed equipment” pertains to NRTL-listed equipment that has been altered somehow. As the NRTL’s safety tests only certify unmodified equipment, the modification of NRTL-listed equipment is usually considered to void any safety certifications it possesses.

Safeopedia Explains Modified NRTL-Listed Equipment

The NRTL-listing program provides a way for OSHA to ensure that the organizations that certify the safety of electrical equipment actually possess the capabilities to do so. The program has been in effect since 1989 and has since become an integral part of OSHA’s product safety enforcement regime.

Prominent NRTLs include UL (Underwriters Laboratories), CSA Group and TUV. Note that the latter two organizations are Canadian and German, respectively — although the program is American, a laboratory does not have to be based in the United States for OSHA to recognize it as an NRTL.

Besides OSHA, the National Fire Protection Association’s (NFPA’s) electrical safety standards (NFPA 70, also known as the National Electrical Code) and workplace electrical safety standards (NFPA 70e) both include requirements mandating that NRTL-listed equipment be used whenever possible. Other US agencies, such as the Department of Energy, may also mandate their use in certain contexts.

In general, these organizations require non-NRTL-listed equipment to be inspected by a certified electrical professional to ensure that it can be used safely. This inspection is required before the equipment can be used safely within the workplace.

For safety purposes, NRTL-listed equipment is considered to lose its listed status once modified, which means that it cannot be used until it is first inspected by a qualified professional. The modification of equipment can be an issue in workplaces such as laboratories, where workers may find it necessary to modify a piece of equipment to better suit their needs.

Many organizations use NRTL listings as part of their own internal safety standards. For instance, the US government’s National Laboratories all have policies that require workers to refrain from using modified NRTL-listed equipment if it has not first been assessed by a qualified inspector.


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