That frame rating means the breaker's mechanical and thermal capacity is sized for the full 4800 A interrupting duty — the 400 A continuous setting is a thermal-magnetic or electronic trip threshold, not a hardware limit. Three-pole construction, line-protection design — this is the main breaker role, not a feeder or motor-circuit protector. Max power loss is 63.5 W, which matters for heat buildup in a sealed panel.
Interrupting capacity across voltage levels
The SCCR drops as line voltage climbs: 187 kA at 240 V, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 9 kA at 690 V. At 690 V the 9 kA figure is the breaker's limit — if your system fault current exceeds that at this voltage, you need a different frame or a current-limiting upstream device. For most 400 V-class industrial distribution, 121 kA is ample headroom.