It carries a maximum breaking capacity of 187 kA at 240 VAC, stepping down to 121 kA at 415/440 V, 75.6 kA at 500 V, and 7.5 kA at 690 V — so the short-circuit rating you need depends on the system voltage it's protecting.
The 400 A rating holds steady up to 50 °C ambient. Above that, it derates linearly: 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C.
