400 A MCCB with 187 kA interrupting capacity — selectivity anchor for high-fault panels
Its headline interrupting ratings — 187 kA at 240 V, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 17 kA at 690 V — mean this breaker can clear a bolted fault at those levels without rupturing, which is the deciding factor for main or feeder positions in high-capacity distribution switchboards where upstream transformer impedance is low. It does not include an undervoltage release or phase failure detection, so those functions must be added externally if required.
Rated at 400 A from 40 °C through 50 °C ambient, the breaker derates to 375 A at 55 °C, 350 A at 60 °C, 325 A at 65 °C, and 300 A at 70 °C. The 110 mm depth, 138 mm width, and 248 mm height fit standard MCCB mounting footprints; verify the busbar connection centers against the existing panel layout. Maximum power loss is 96 W, which contributes to the enclosure heat load — account for this when sizing ventilation or cooling for a multi-breaker lineup.