Its interrupting capacity reaches 242 kA at 240 V AC and 187 kA at 415 V and 440 V — numbers that tell you it handles high-fault-current scenarios like transformer secondaries or large motor branch circuits without cascading upstream.
Rating so-what: thermal derating and interrupting capacity
The 250 A rating holds steady from 40 °C through 50 °C, then derates to 238 A at 55 °C, 225 A at 60 °C, 213 A at 65 °C, and 200 A at 70 °C. The interrupting curve drops sharply at 690 V to 4.5 kA — this breaker is not your go-to for 690 V high-fault applications; at that voltage, the 121 kA at 500 V is the realistic ceiling for heavy-duty service.