What this RCCB is and what the ratings mean
The Siemens 5SM3344-6LA is a SENTRON residual current circuit breaker (RCCB) — the thing that kills power the instant it senses a ground fault leaking to earth. Four poles, Type A waveform detection, and it carries a 40 A continuous rating at 400 V AC, 50 Hz. The 30 mA trip threshold is the standard for personnel protection (shock hazard), and the 10 kA short-circuit current rating (SCCR) means it can safely interrupt a fault up to that level without welding its contacts shut or blowing apart. That 10 kA number is what the upstream breaker needs to coordinate with — if your available fault current at the panel exceeds 10 kA, this RCCB isn't the right choice without a current-limiting device ahead of it.
DIN rail fit and panel integration
Snaps onto a standard DIN rail (REG profile), takes up 4 width units (about 72 mm), and installs 70 mm deep. Mounting position is any orientation, and the supply can land top or bottom — no forced busbar order. The terminals accept 1.5 mm² minimum up to 25 mm², which covers most panel wiring from control circuits up to the incoming feed for a sub-distribution board. IP20 with the distribution board cover fitted, so it's meant for enclosed panels, not washdown areas.
Lifecycle and sourcing reality
This part is marked as current production — no phase-out notice, no last-time-buy window to chase. It's a standard catalogue item in the SENTRON 5SM3 family. Sourced and quoted to order against an RFQ through independent distribution; availability and current pricing confirmed at quote time. If you're freezing a BOM or filling a line-down gap, this one isn't a scavenger hunt.