The Siemens 5SM3312-0KL is a SENTRON 5SM3-series residual current circuit breaker (RCCB) — 2-pole, type AC, rated 25 A with a 30 mA trip threshold at 230 V AC.
Snap-on DIN rail (REG) mounting, any orientation, 70 mm installation depth. Terminals accept 1–16 mm² solid or stranded copper — that range covers everything from 1.5 mm² lighting circuits up to 16 mm² submains. Tightening torque 2.5–3 N·m; strip length is standard for the terminal design. IP20 with conductors connected and distribution board installed — fine for enclosed panels, not for open wet locations. Supply can enter top or bottom; the test circuit needs at least 100 V to operate the test button. Ambient range -5 to +45 °C operating, -40 to +75 °C storage. Overvoltage category III — suitable for fixed installation downstream of the utility meter.