Listed, labeled, and defined in the National Electrical Code
What exactly does "listed and labeled as defined in NFPA 70" mean?
Listing and labeling is not confined just to NFPA 70: National Electrical Code. Just about every piece of IT, electrical, mechanical, and plumbing equipment—along with almost all building materials—are governed by standards that specify certain physical and operational characteristics.
Before a product is listed and labeled, there must be a standard and a body to develop the standard. The body is called a standards developing organization, or SDO. The SDO is ideally a nationally recognized organization accredited by the American National Standards Institute (ANSI) to develop, maintain, and support voluntary national standards. An SDO is not always accredited by ANSI—there are several reasons for this, but most often it is because the SDO does not adhere to ANSI's open, consensus-based development and maintenance process. For more on this, here is a short explanation of ANSI and standards development.
The SDO has primary responsibility for the standard or standards that ANSI accredits. The SDO that produces NFPA 70 is the National Fire Protection Association. Through the open, consensus-based process, the NFPA reviews the content in NFPA 70, and every 3 years issues and updates the standard. NFPA 70 describes the products that are used for general electrical construction and the physical and operational characteristics that a product should meet in order to operate safely. NFPA 70 also indicates test standards that some products are required to meet.
A Nationally Recognized Testing Laboratory (NRTL) is a separate entity from the SDO that may be required to test the product or products described in the standard to verify that products meet the requirements of the standard. Each NRTL is recognized by the Occupational Safety and Health Administration (OSHA) to test certain products and has registered certification marks that are applied to each product. Your likely very familiar with several of these organizations and their certification marks (links lead to explanation of the marks); Intertek's ETL, UL, CSA, and FM are some of the better known NRTLs. Here is a complete list of NRTLs. Be careful when describing these labels, as there is a difference between labels that approve, recognize, or certify components or products. Also be sure that the manufacturer and label are properly listed, as the counterfeit market for electrical products is booming in the United States.
Product testing to certify the label may be done on a per-item basis, where every item that comes out of a factory is tested, or on a representative product, which is a product identical in construction and operation to all products off that particular assembly line.
That covers "listed" and "labeled." But what exactly does "as defined in NFPA 70" mean? Article 100 of NFPA 70 defines listed and labeled—in short, components or products have to be approved by the authority having jurisdiction (AHJ), and labeled to indicate compliance. Typically, the NRTL will produce this list or a manufacturer's specification will indicate compliance with the standard. The actual product that shows up at the jobsite will have a label on it indicating compliance.
Note that "approved" and "AHJ" also are defined in Article 100 of NFPA 70. Both terms are used in the definition of listed, so theoretically, this allows the AHJ to vet certain products or manufacturers. The place to do this is in the list of manufacturers or products in the specifications included within the contract documents. The specification is the only place this can be done, and if a nonstandard product is desired, use of this list is absolutely essential to allow use of the product.
Michael Heinsdorf, PE, LEED AP, CDT is an Engineering Specification Writer at ARCOM MasterSpec. He has more than 10 years of experience in consulting engineering, and is the lead author of MasterSpec Electrical, Communications, and Electronic Safety and Security guide specifications. He holds a BSEE from Drexel University and is currently pursuing a Masters in Engineeringo at Drexel University.