The EZC400N4300 is a 4-pole molded case circuit breaker from the EasyPact EZC400N series, rated 400 A at 40 °C with a TM-D thermal-magnetic trip unit. The headline breaking capacity is 36 kA Icu at 440 V AC (50/60 Hz) per IEC 60947-2 — that is the maximum fault current it can safely interrupt without damage at that voltage. At 220/230 V AC the same frame delivers 40 kA Icu. For distribution panels feeding downstream sub-distribution or heavy motor loads, the 36 kA rating at 400/415 V gives solid selectivity headroom against a typical 25 kA or 50 kA upstream transformer. The trip unit rating is 300 A at 50 °C, so if your enclosure runs hot, the breaker derates — plan your load at the 50 °C figure if the panel is not ventilated. IP20 finger-safe protection on the front face; the enclosure itself is rated IK07 for impact resistance.
Compliance documentation covers EN/IEC 60947-1, JIS C8201-2-2, GB/T 14048.2, and EN/IEC 60947-2. The breaker is certified for isolation per IEC 60947-2.
Dimensions: 255 mm high × 185 mm wide × 140 mm deep. The 185 mm width on a 4-pole frame is standard — verify backplate clearance against your enclosure depth. Front-connect terminals on both sides simplify busbar routing but mean the breaker cannot be rear-connected without an adapter. The toggle handle provides positive contact indication (red/green flag) so you can visually confirm open/closed state without removing the cover. Electrical endurance is 4000 cycles at 415 V AC (Category A per IEC 60947-2). Mechanical endurance is 10,000 cycles. For a distribution breaker that cycles infrequently (a few times a year for maintenance isolation), this is ample. If your application requires frequent switching under load — say a welding line or a test bench — consider a dedicated switch-disconnector instead.