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As one of the most trusted safety certification organizations, Underwriter’s Laboratory (UL) is heavily involved in the work of the National Fire Protection Association when it comes to NFPA 70: National Electric Code (NEC). In fact, UL has helped to update and maintain the NEC since its very first edition in 1897. In order to react to changes in user needs, as well as respond to ever-changing technology, the NEC is revised based on a public input process, committee review, and adoption into the code.

The NEC is divided into 19 different Code Panels, which are essentially the advisory boards that review, maintain, and update the various sections of the NEC. Every 3 years (one “Code Cycle”), the NEC is reissued with updates and revisions based on the work of these Code Panels. Public Inputs (comments, concerns, and recommendations from organizations, companies, or even individuals) are the means by which the public plays a role in the code change process. Furthermore, the public can respond to actions taken by the Code Panels by submitting Public Comments. UL has a representative on each of the 19 Code Panels. Thus, by working closely with the NFPA, UL not only aligns and adjusts its own standards, but also influences the NEC revisions as well.

When it comes to the NEC, requirements are set forth for “Listed” products, causing manufacturers to seek to certify their products for code compliance. UL is one of the leading choices for certification to meet these requirements (although there are others as well). Thus, the link between the NEC and UL is the Listing requirement. The NEC establishes listing requirements, and UL meets those requirements in what it certifies (bearing in mind that the term “Listed” as used in the NEC is not the same as “UL Listed”). Ultimately, although UL can and does enforce its own standards on those who carry the UL mark), it cannot and does not enforce the NEC standards. That comes down to the particular Authority Having Jurisdiction (AHJ).

Ultimately, the NEC is a demand driver for UL certification services. It bases its code standards upon certification agencies such as UL. At the back of the NEC, in “Annex A: Product Safety Standards,” the type of product and certifying standard associated with it can be found. The certifying standard is the basis upon which the NEC requirements have been determined.

For example:

  • What safety standard is used in determining NEC requirements for an electric motor? UL 1004.
  • What safety standard is used in developing the NEC requirements for Industrial Control Panels? UL 508A.
  • What safety standard was used in developing the NEC requirements for Surge Arresters—Metal-Oxide Surge Arresters for AC Power Circuits? IEEE C62.11.

Thus, this annex essentially serves as a bibliography of sorts, telling you the source material used in developing the NEC. What is important to notice is that a large majority (over 90%) of the Product Standards are based upon UL standards. Thus, in a sense, being familiar with UL makes one inherently familiar with much of the NEC.