NEMA Publishes AB 3-2006, Molded Case Circuit Breakers and Their Application

ROSSLYN, VA, January 19, 2007-The National Electrical Manufacturers Association (NEMA) has published AB 3-2006, Molded Case Circuit Breakers and Their Application, which replaces AB 3-2001.

This standard is an application guide to assist the user in the selection and operation of molded case circuit breakers in electrical systems up to 600 volts. It describes the various kinds of molded case circuit breakers available and the features and accessories associated with them. AB 3-2006 explains specific purpose categories and construction variations, as well as ratings and National Electrical Code® (NEC®) requirements. (National Electrical Code and NEC are registered trademarks of the National Fire Protection Association.) Selection criteria are also provided, including main, feeder and branch circuits, load requirements, time-current curves, selective coordination, series application, ground fault protection, and arc fault protection. It also provides information on Underwriters Laboratories (UL) requirements under UL 489 for listed, recognized, and classified circuit breakers.

AB 3-2006 has been revised to address current marketplace requirements, including making the document more user friendly. Additional information has been included on 100 percent rated circuit breakers, selective coordination, and zone selective interlocking. The standard has also been updated to the latest references and changes to the NEC. Parts of Section 5 on the selection of molded case circuit breakers have been reorganized for clarity.

AB 3-2006 may be downloaded free, or a hardcopy purchased for $75.00 by visiting NEMA's website at, or by contacting IHS at (800) 854-7179 (within the U.S.), (303) 397-7956 (international), (303) 397-2740 (fax).

NEMA is the trade association of choice for the electrical manufacturing industry. Founded in 1926 and headquartered near Washington, D.C., its approximately 450 member companies manufacture products used in the generation, transmission and distribution, control, and end-use of electricity. These products are used in utility, medical imaging, industrial, commercial, institutional, and residential applications. Domestic production of electrical products sold worldwide exceeds $120 billion. In addition to its headquarters in Rosslyn, Virginia, NEMA also has offices in Beijing, São Paulo, and Mexico City.

Diane Davis
(703) 841-3222


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