What this 400 A MCCB actually does on the line
The Schneider Electric EZC400N3400N is a 3-pole molded case circuit breaker from the EasyPact EZC400N family, rated 400 A at 40 °C with a TM-D thermal-magnetic trip unit. The 36 kA Icu at 440 V AC (50/60 Hz) means it can safely interrupt a fault current of that magnitude without welding contacts or venting plasma into the panel — that's the number that decides whether it holds on a 400 V distribution bus or blows upstream. It's a Category A breaker (no intentional short-time delay), so it's built for fast clearing on feeder and distribution duty, not selective coordination downstream of a main. The 400 A frame with a 5000 A magnetic trip threshold gives it a solid pickup for motor-start inrush or transformer energization without nuisance tripping.
Breaking capacity — the real fit gate
The N breaking capacity code on this EZC400N3400N delivers 36 kA Icu at 440 V AC and 40 kA at 220/230 V, both per IEC 60947-2. The TM-D trip unit gives fixed thermal and magnetic settings — no interchangeable rating plugs, so the 400 A is what it is.
Fixed mounting on a backplate — no DIN rail, so plan for a drilled mounting surface or an enclosure sub-panel. Front-front connections (line and load both front-accessible) simplify busbar runs and cable entry in a dead-front enclosure. IP20 finger-safe terminals are standard; IK07 impact rating means it handles accidental tool drops during panel work.
Positive contact indication on the toggle gives visual confirmation of contact position. The thermal-magnetic trip covers both overload (thermal) and short-circuit (magnetic) protection. No earth-leakage protection built in; if ground-fault is required, pair it with an external RCD or specify the EZC400N with a Vigil option.