The Siemens SENTRON 5SU1323-1BB25 is a 2-pole RCBO (residual current circuit breaker with overcurrent protection) rated 25 A, 230 V AC, with a 30 mA residual tripping current and C characteristic. It breaks fault currents up to 4.5 kA per EN 60898 and 15 kA per IEC 60947-2, so it handles both the standard household fault level and the higher industrial short-circuit rating for panel feeders. The 30 mA sensitivity covers personnel protection against direct contact — that's the standard threshold for socket-outlet circuits in most residential and light commercial installations.
The 30 mA residual current is the go-to for wet-room and socket circuits; if you're feeding fixed equipment with known leakage, step up to 100 mA or 300 mA. The 4.5 kA breaking capacity under EN 60898 covers the typical domestic service entrance; the 15 kA rating under IEC 60947-2 means it also qualifies for industrial sub-distribution boards where fault levels are higher. The IP20 rating applies once the distribution board is closed; the device itself is touch-protected (fingertip-safe terminals).
Neutral conductor switching is built in (2-pole switching, line + switched neutral), so no external neutral link is needed. The terminals accept the usual 0.2–2.5 mm² conductors; strip length is 8 mm. Ambient temperature range is -40 to 75 °C, with max 95% humidity — fine for unheated utility rooms or outdoor-rated enclosures.