NEMA AB 5

Description / Abstract: The scope of this standard includes all types of circuit breakers listed to: 1) The UL 489 Molded-Case Circuit Breakers, Molded-Case Switches and Circuit-Breaker Enclosures 2) The UL 1066 Standard for Safety Low-Voltage AC and DC Power Circuit Breakers Used in Enclosures The standard specifically addresses achieving selective coordination at high levels of short circuit fault current in the instantaneous region of the circuit breaker time-current curve by use of selective coordination tools. This requires taking into consideration more information than is typically found on conventional Time-Current Curves TCCs only. This includes molded case circuit breakers and insulated case circuit breakers. It specifically addresses instantaneous selective coordination as achieving selective coordination at high levels of fault current, and may require taking into consideration more information than is typically found on conventional TimeCurrent Curves TCCs only. 1.2 Referenced Standards In this publication, reference is made to the latest edition of the standards listed below. Copies are available from the indicated sources. Other references are listed at the end of this standard. National Electrical Manufacturers Association 1300 North 17th Street Rosslyn, Virginia 22209 AB 1 ABP 1 Molded Case Circuit Breakers, Molded Case Switches and Circuit Breaker Enclosures Selective Coordination National Fire Protection Association Batterymarch Park Quincy, MA 02269 NFPA 70 National Electrical Code ® 1