The C11N4TM040B is a Schneider Electric ComPacT NSXm moulded-case circuit breaker rated 40 A at 40 °C, 4 poles, with a TM-D thermal-magnetic trip unit. It carries a 50 kA breaking capacity at 415 V AC (performance level N) and is certified to EN/IEC 60947-2 for distribution duty.
What the ratings mean for fit
The 40 A rating at 40 °C is the continuous current the breaker carries without tripping in a 40 °C ambient — typical for a panel that's not actively cooled. The 50 kA at 415 V AC is the maximum fault current it can safely interrupt; that's enough for most commercial and light industrial distribution boards downstream of a transformer. The 4-pole version (4P) switches all three phases plus neutral, so it's the right choice for a TN-S or TN-C-S system where you want full isolation on the neutral. The TM-D trip unit is thermal-magnetic: the thermal element handles overloads (slow response), the magnetic element handles short-circuits (instantaneous). Category A utilisation means it's not intended for selective coordination with downstream breakers — it trips fast on fault, no intentional delay. IP40 and IK07 mean it's protected against tools and wires >1 mm but not against water ingress — mount it inside a panel, not outdoors. Pollution degree 3 (IEC 60664-1) means it's rated for conductive pollution or dry non-conductive pollution that becomes conductive due to condensation, which is the standard for most industrial control panels.
Mounting and integration
Mounts on a backplate (not DIN rail) — horizontal or vertical, flat on the back. The 9 mm pitch takes 12 modules of panel space. Connection terminals accept compression lugs or busbars; front connection on both upside and downside keeps wiring accessible. Neutral sits on the left.