The Siemens SENTRON 5SM3444-6LA is a 4-pole residual current circuit breaker (RCCB) from the 5SM3 design series, rated for 40 A at 400 V AC, with a 100 mA trip threshold and Type A fault current sensitivity. It includes integrated thermal overload protection, distinguishing it from a bare RCCB — it combines residual current and overcurrent protection in one DIN-rail unit.
The 40 A continuous rating and 100 mA residual trip define the load it can carry and the leakage it will clear. Type A detection responds to sinusoidal AC and pulsating DC faults. The 10 kA short-circuit current rating is the fault level the device can safely interrupt. Wire range accepts 1.5 to 25 mm² solid or stranded, covering most distribution circuit conductors up to 40 A. The screw terminals call for 2.5 to 3 N·m — per the datasheet, that's the torque window for reliable connection without stripping the clamp.
Snap-on DIN rail (REG) mount, 4 width units. Installation depth is 70 mm. Finger and back-of-hand safe per the shock-protection classification — the terminals are recessed so accidental contact during commissioning is prevented when the cover is on.