NEMA, IEEE, UL, and ANSI

NEMA, the National Electrical Manufacturers Association, states in its technical FAQ that it is not an enforcement agency and that its standards are voluntary. If a manufacturer labels a product as meeting a NEMA standard, that's the manufacturer self-certifying. NEMA is a trade association, and its members are the equipment manufacturers whose products the standards describe. Its documents exist to give the industry a shared, agreed-upon vocabulary for enclosure ratings, motor tolerances, and equipment dimensions.

ANSI, the American National Standards Institute, sits one level up from both NEMA and IEEE as a referee of the process. ANSI accredits organizations like NEMA to develop what are called American National Standards, meaning it certifies that the organization followed a recognized, open, consensus-based development procedure. Historically, much of the electrical standards work that carries an ANSI designation was authored and edited by IEEE, with ANSI functioning closer to a publisher lending its accreditation than a technical body producing content. That is why so many documents carry both names stacked together, as in ANSI/IEEE or ANSI/NEMA.

IEEE, the Institute of Electrical and Electronics Engineers, is where most of the engineering guidance lives. The thermal-aging models in C57.91, the voltage-range tables in C84.1, and the interconnection requirements in 1547 and its supplements. IEEE is a professional engineering association, not a manufacturer's trade group and not a certification body, and its standards are exactly as voluntary as NEMA's on their own terms. PG&E's distributed generation interconnection requirements state that they were written in alignment with IEEE 1547.6, which is what makes that IEEE document relevant to a specific interconnection request in PG&E's territory.

UL or Underwriters Laboratories does independent testing and certification. The Occupational Safety and Health Administration (OSHA) maintains a formal recognition category called a Nationally Recognized Testing Laboratory, established under 29 CFR 1910.7, and UL is one of the organizations OSHA has recognized under that program. OSHA's guidance is explicit that this recognition is an acknowledgment that UL meets specific criteria for independent testing and certification. But because OSHA's workplace safety regulations require certain categories of equipment to be certified by a recognized testing laboratory before it can be used in a workplace, UL's certification becomes something an employer is legally required to have. The enforcement comes from OSHA, with UL as the recognized certifier standing in the gap.