What this 4-pole MCB delivers for the panel
Its 25 kA breaking capacity per IEC 60947-2 gives you headroom on a 400 V distribution board with a high-fault utility transformer; the 5 kA rating per UL 1077 and CSA C22.2 No.235 covers North American panel builds where the available fault current is lower. Tightening torque is 2.5 to 3.5 N·m, typical for a 35 mm² clamp. The breaker is sealable (padlockable handle) for lockout/tagout, and touch-protected per IP20 with connected conductors.
Rated for overvoltage category III, so it's suited for fixed-installation distribution boards downstream of the main incoming supply.
What the C-curve and breaking capacity mean for selectivity
C-curve (tripping characteristic class C) means the magnetic trip fires at 5 to 10 times rated current — so for a 25 A breaker, the instantaneous trip threshold is between 125 A and 250 A. That's high enough to pass the starting current of a 7.5 kW motor on a 25 A feeder but low enough to clear a bolted fault before upstream devices see it. The 25 kA rated short-circuit capacity at 400 V AC (IEC 60947-2) means this breaker can safely interrupt a fault up to that level without welding its contacts or cascading damage to downstream wiring — a key spec for coordination studies on a 400 V distribution board with a transformer larger than 630 kVA.