NEMA AB 4-2017规定了一些基本程序，供合格人员使用，这些程序可用于检查和预防性维护工业和商业应用中使用的塑壳断路器，额定值为1000 V 50/60 Hz ac或ac/dc。

NEMA AB 4-2017 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.