The National Electrical Manufacturers Association (NEMA) has published ANSI C12.20-2010, "American National Standard for Electricity Meters—0.2 and 0.5 Accuracy Classes." The standard, last published in 2002, was produced by the ANSI C12 Accredited Standards Committee for Electricity Metering, Subcommittee 16.

ANSI C12.20 establishes acceptable performance criteria for electricity meters, and covers accuracy class designations, current class designations, voltage and frequency ratings, test current values, service connection arrangements, pertinent dimensions, form designations, and environmental tests.

In this revision, the standard was broadened to allow three-phase current and voltage sources as an optional test method to the existing single-phase, series, parallel method.

The contents and scope of ANSI C12.20 may be viewed, or a hardcopy or electronic copy purchased for $67, by visiting www.nema.org/stds/c12-20.cfm or by contacting IHS at (800)-854-7179 (within the United States), (303) 397-7956 (international), or global.ihs.com.