The Siemens 5SM3412-6 is a 2-pole residual current circuit breaker (RCCB) from the SENTRON 5SM3 series, rated for 25 A at 230 V AC, 50 Hz, with a 100 mA trip threshold. That 100 mA sensitivity is a step above the standard 30 mA personal-protection level; it's sized for equipment protection or for circuits where nuisance tripping from leakage on long cable runs or filter caps would be a problem. The 2-pole form factor (switching both line and neutral) and the 36 mm width (2 width units on DIN rail) mean it drops into a standard distribution board without crowding adjacent breakers.
Mounting and environment — no special treatment needed
Mounts on DIN rail (REG) in any position — top or bottom feed, horizontal or vertical panel orientation — which gives the panel builder flexibility when laying out a crowded enclosure. The IP20 rating (finger-safe, with conductors connected) is standard for enclosed distribution boards; no washdown or outdoor pretensions here. The current derating curve is published: full 25 A up to 45 °C, then linearly down to 17.5 A at 70 °C. If the RCCB sits next to high-draw breakers in a sealed enclosure, that derating matters — account for the internal temperature rise.
Wire termination and panel integration
Terminals accept 1 to 16 mm² solid or stranded copper — covers everything from a 1.5 mm² lighting circuit up to a 16 mm² feeder. Installation depth is 70 mm, height 90 mm, width 36 mm.