Standards and ratings for the application of molded-case, insulated-case, and power circuit breakers

Molded-case circuit breakers (MCCBs), insulated-case circuit breakers (ICCBs), and power circuit breakers (PCBs) are used by electrical engineers in power distribution system designs primarily to protect low-voltage electrical equipment and circuits. Safe application requires an understanding of their performance and ratings. Proper application of these devices can ensure continuity of power during system disturbances. This discussion focuses on domestic standards and ratings for the application of low-voltage industrial-grade MCCBs, ICCBs, and PCBs rated 600 V AC or lower for use in switchboards and switchgear. A comparison of switchboard and switchgear requirements for the devices is also included where it is useful.