The C125N42EFM is a Schneider Electric ComPacT NS new generation moulded-case circuit breaker (MCCB) from the NS630b...1600 range, rated 1250 A at 50 °C with a MicroLogic 2.0 E electronic trip unit. At 415 V the rating holds at 50 kA, still well above typical industrial service-entrance requirements. The MicroLogic 2.0 E provides L (long-time overload) and I (instantaneous short-circuit) protection curves, with a 20-minute thermal memory that prevents nuisance tripping on re-energisation after a hot overload. The electronic trip unit gives better accuracy and repeatability than thermal-magnetic alternatives, especially across ambient temperature swings.
Fixed backplate mount, 327 mm high by 280 mm wide by 147 mm deep — sized for a standard MCC bucket or standalone enclosure. Front connection both top and bottom, with a 70 mm connection pitch that matches common busbar and cable-lug patterns. IK07 impact rating handles accidental tool drops during panel work. Neutral is on the left, which matters when wiring a 4-pole breaker into an existing bus run — verify your busbar phasing matches before landing lugs.