The Schneider Electric EZCV250N4125 is a 4-pole molded case circuit breaker from the EasyPact EZCV250N series, rated 125 A at 40 °C with a TM-D thermal-magnetic trip unit. It carries a 20 kA Icu breaking capacity at 440 V AC (50/60 Hz) per IEC 60947-2, which means it can safely interrupt fault currents up to that level without upstream damage — the key number for panel coordination. The breaker also includes integral earth-leakage protection, so it handles both overload/short-circuit and ground-fault detection in one device, saving a separate relay and CT.
Above that ambient, you derate per the thermal curve — a panel running at 50 °C will need a higher-frame breaker or active cooling. The 85 kA Icu at 220–240 V shows the breaker's arc chamber is sized for high-fault residential or light commercial secondaries, but the 20 kA at 440 V is the number that governs most industrial distribution panels. The TM-D trip unit is a fixed thermal-magnetic design — no interchangeable trip plugs.
Fixed backplate mount, front-front connections (both line and load on the front face). At 140 mm wide × 165 mm high × 68 mm deep, it fits a standard distribution section without crowding — three of these side-by-side in a 480 mm wide enclosure leaves room for cable ducts. The toggle handle gives positive contact indication (visible red/green flag), so an operator can confirm open/closed state through the panel door cutout.