The C100H420FM is a Schneider Electric ComPacT NS new generation 4-pole circuit breaker, rated 1000 A at 50 °C with a MicroLogic 2.0 electronic trip unit. It sits in the ComPacT NS630b…1600 new generation family, built for distribution duty in fixed-mount backplate installations. The 85 kA Icu at 240 V AC (70 kA at 415 V, 65 kA at 440 V) tells you it handles high-fault utility feeds without cascading upstream — the H breaking capacity code means it's the 70 kA 415 V variant.
That's the number you match to your bus or cable ampacity — not the frame size, not the interrupting rating. The MicroLogic 2.0 provides L (long-time overload) and I (instantaneous short-circuit) protection curves; no ground-fault module on this unit. Breaking capacity is the real selectivity gate. At 415 V AC the C100H420FM interrupts 70 kA symmetrical — that's enough for most industrial secondary-distribution switchboards. The breaker is Category B (IEC 60947-2), meaning it's fully rated for discrimination with downstream devices. Mount it on a backplate with the 70 mm connection pitch — front connections both top and bottom, neutral on the left.