It carries a 40 A thermal-magnetic TM-D trip unit that provides L (overload, thermal) and I (short-circuit, magnetic) protection — the thermal element handles sustained overloads; the magnetic element clears hard faults fast. At 220/240 V AC the C10B4TM040C interrupts 40 kA Icu; at 380/415 V AC that figure is 25 kA Icu; at 440 V AC it's 20 kA Icu; and at 500 V AC it's 15 kA Icu, all per IEC 60947-2. For a 400 V panel fed by a transformer with typical available fault current in the 18–22 kA range, the 25 kA rating at 415 V gives solid headroom — you're not riding the edge of the curve.
Backplate-mounted with front-facing connections top and bottom. Mounts horizontally or vertically flat on the backplate; the toggle stays accessible either way.
IK07 impact resistance means it handles a 2 J tool drop without cracking the case. Operating altitude is 0–2000 m at full rating; derate above that up to 5000 m.
Durability and electrical life
Mechanical endurance is 50,000 cycles. Electrical durability depends on the load: 50,000 cycles at 440 V at half rated current (In/2), 30,000 cycles at full In, 20,000 cycles at 690 V In/2, and 10,000 cycles at 690 V In. For a breaker that mostly sees infrequent switching (panel feeder, not a motor-starting contactor), that's more than adequate — you'll retire the panel before you hit those numbers.