The Schneider Electric C16N4TM125 is a ComPacT NSX160N moulded-case circuit breaker (MCCB) with a 125 A thermal-magnetic TM-D trip unit, 4 poles, and an N-frame breaking capacity of 50 kA Icu at 415 V AC. At 690 V the same breaker still holds 10 kA Icu, which covers most industrial step-down transformer secondaries. The thermal-magnetic TM-D trip gives you fixed thermal overload (L) and fixed magnetic short-circuit (I) protection curves — no interchangeable rating plugs, no electronic adjustment, just a straightforward, field-proven design for distribution panels where you set it and leave it.
Mounts flat on a backplate — no DIN-rail adapter here, so plan for a drilled and tapped panel or a universal mounting bracket. The 140 mm width and 161 mm height fit a standard 4-pole MCCB cutout; depth is 86 mm, which leaves room for rear-connected busbars or cable ladders. Connection pitch is 35 mm per pole, matching standard busbar systems. The breaker can be mounted horizontally or vertically, which helps when you are squeezing it into a shallow or oddly oriented enclosure.
Standards, approvals, and environmental ratings
Pollution degree 3 (IEC 60664-1) means it handles conductive dust and humidity typical of industrial control rooms and factory floors. IP40 enclosure protection keeps out tools and small debris; IK07 impact resistance handles accidental bumps during panel wiring.
Electrical durability and application context
Rated for 40,000 mechanical cycles and 20,000 electrical cycles at 440 V at full rated current — that is a solid lifespan for a distribution breaker that sees occasional switching, not daily motor starts. The utilisation category is A, meaning it is intended for distribution (not direct motor switching), so pair it with a contactor for motor loads. The 4-pole version with neutral protection set at 1 x Ir (full pole protection on all four poles) is the right choice for a 3-phase + neutral distribution board where you need to protect the neutral against harmonics or unbalanced loads.