The EZC400H4300 is a 4-pole molded case circuit breaker from Schneider Electric's EasyPact EZC400H series, rated 400 A at 40 °C with a TM-D thermal-magnetic trip unit. The TM-D trip unit provides both short-circuit (magnetic) and overload (thermal) protection, with a magnetic tripping threshold of 3500 A, so it clears hard faults fast while riding through motor inrush. This breaker is Category A (no intentional short-time delay), which means it's suited for distribution applications where you don't need selective coordination with downstream breakers — it's the right-sized spec for main switchboard or large feeder duty, not for a time-delayed selective trip scheme.
Compliance documentation is straightforward: the breaker carries IEC 60947-2, JIS C8201-2-2, and GB/T 14048.2 certifications, plus it's suitable for isolation per IEC 60947-2.
The 45 mm connection pitch matches typical busbar or cable lug spacing. IP20 finger protection on the front face is adequate for enclosed panels; IK07 impact resistance means it can take a knock during installation without damage to the housing. Dimensions are 255 mm high, 185 mm wide, 140 mm deep — that's a compact footprint for a 400 A frame, so it fits in standard distribution boards without crowding adjacent breakers. The toggle control and positive contact indication give clear visual status for commissioning and maintenance.
Mechanical durability is rated at 10,000 cycles, electrical durability at 4,000 cycles at 415 V AC — that's typical for a distribution breaker in a panel that sees occasional switching, not continuous motor-starting duty. For applications that need frequent switching, you'd look at a contactor or a dedicated motor circuit protector; this breaker is sized for distribution protection where the load is mostly static.