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.
Molded-case circuit breakers have diverse uses in several commercial and industrial applications. NEMA AB 4 is designed to guide qualified personnel during inspection and maintenance.
The standard sets forth, for use by qualified personnel, a number of basic procedures that may be used for the inspection and preventive maintenance of molded-case circuit breakers used in industrial and commercial applications rated up to and including 1,000 V 50/60 Hz ac or ac/dc.
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