What the ratings mean for fit
The C12E6TM125B is a Schneider Electric ComPacT NSXm moulded-case circuit breaker, 4-pole, with a thermal-magnetic TM-D trip unit rated 125 A at 40 °C. The 16 kA breaking capacity at 415 V AC (performance level E) tells you it can safely interrupt a fault current up to that level without upstream devices needing to clear it — relevant for distribution panels where the available fault current is known. The TM-D trip unit combines a thermal bimetal for overload protection and a magnetic coil for short-circuit protection; the D curve means the magnetic trip threshold is higher than a standard B or C curve, suited for loads with moderate inrush like small motors or transformers. The 4-pole version (4P) switches all three phases plus the neutral, with the neutral on the left per the listing. The IP40 enclosure rating means it's protected against solid objects over 1 mm but not against water ingress — mount it inside a panel, not in a washdown area. The IK07 impact rating confirms it withstands a 2 J impact, typical for panel-mounted gear.
Standards and compliance
The breaker is designed and tested to EN/IEC 60947-2, the standard for low-voltage switchgear and controlgear. It is suitable for isolation per that standard (yes conforming to IEC 60947-2). Pollution degree 3 per IEC 60664-1 means it's rated for industrial environments where conductive pollution occurs. Overvoltage category III applies to fixed-installation distribution boards.
Mounting and integration
Mounts on a backplate — not a DIN rail — in horizontal or vertical orientation, flat on the back. The 12-module 9 mm pitch width (108 mm) and 137 mm height fit standard distribution board cutouts. Connection terminals accept compression lugs or busbars; both upside and downside connections are front-facing, simplifying panel wiring. The connection pitch is 35 mm with spreaders, 27 mm without.