The C25N4TM125 is a Schneider Electric ComPacT NSX moulded-case circuit breaker with a 125 A thermal-magnetic TM-D trip unit, 4 poles, and a breaking capacity code of N — 50 kA Icu at 415 V AC per IEC 60947-2. That 50 kA at 415 V is the number that governs selectivity in a distribution board fed by a transformer of that voltage class; the same breaker delivers 90 kA Icu at 240 V AC and 10 kA at 690 V AC, so it can serve as a main or feeder breaker across a range of system voltages without swapping frames. The thermal-magnetic trip (L for overload, I for short-circuit) means no electronic aux power is needed — it self-powers from the line current, which simplifies replacement in retrofit panels where control wiring is already pulled.
Deployment context
The 140 mm width and 161 mm height fit standard ComPacT NSX cutouts, and the 35 mm connection pitch matches common bus-bar spacing. Rated IP40 (finger-safe) and IK07 (impact resistance), so it suits enclosed switchboards but not washdown zones.
Key approvals and standards
Electrical durability: 20 000 cycles at 440 V at half rated current, 10 000 cycles at full rated current. Mechanical durability: 20 000 cycles.