by Brianna Crandall — October 23, 2017 — The National Electrical Manufacturers Association (NEMA) recently published a new version of NEMA AB 4-2017, Guidelines for Inspection and Preventive Maintenance of Molded-Case Circuit Breakers Used in Commercial and Industrial Applications.
“This revision contains several edits to reflect new industry practices as well as harmonize the industry standards that apply to molded-case circuit breakers,” explained Patrick Salas, chair of the AB4 Task Group, and director, Codes and Standards GE Energy Connections, Industrial Solutions.
According to NEMA, molded-case circuit breakers protect against thermal overloads, short circuits and ground faults by combining a temperature-sensitive device with a current-sensitive electromagnetic device; they have a very diverse use in several commercial and industrial applications.
NEMA AB 4 is designed to guide qualified personnel during inspection and maintenance of molded-case circuit breakers and switches, assembled as integral units in supporting housings of insulating material, having voltage ratings up to and including 1,000 V ac and 1,200 V dc and interrupt ratings of 5,000 A or more.
NEMA AB 4-2017, Guidelines for Inspection and Preventive Maintenance of Molded-Case Circuit Breakers Used in Commercial and Industrial Applications is available for $103 in hard copy or as an electronic download at no cost on the NEMA Web site.