The C125N42AFM is a fixed-mount ComPacT NS new generation MCCB from Schneider Electric, rated 1250 A at 50 °C with a MicroLogic 2.0 A electronic trip unit providing L (long-time overload) and I (instantaneous short-circuit) protection per EN/IEC 60947-2. The 4-pole configuration with neutral on the left handles three-phase distribution with a switched neutral. The IP40 enclosure keeps out tools and wires over 1 mm but not moisture, so mount it in a dry indoor panel or a weatherhead-rated enclosure.
Fixed-mount on a backplate (mounting support), with front-facing connections on both the line and load sides — no rear or plug-in base. Dimensions are 327 mm high, 280 mm wide, 147 mm deep, with a 70 mm connection pitch between phases. The LCD display on the front shows real-time current readings (ammeter measurement type), and four red LEDs signal fault types plus one yellow LED for overload. Pollution degree 3 (IEC 60947) means it tolerates conductive dust in industrial environments, but the IP40 rating still calls for a clean panel interior or an additional enclosure for washdown areas.