The Siemens 5SU9326-1CN25 is a 2-pole residual-current-operated circuit breaker (RCBO) from the SENTRON family, combining overcurrent protection with 30 mA earth-leakage detection in a single 4-module-width unit.
Temperature derating — the real current rating in a warm panel
The 25 A rating applies at 30 °C ambient. Inside a closed distribution board where ambient runs higher, the continuous current must be reduced: 23.3 A at 40 °C, 22 A at 45 °C, 21.5 A at 50 °C, and 20.8 A at 55 °C. If your panel regularly sees 40 °C or above, size the downstream load against the derated figure, not the catalogue 25 A.
Mounting and integration into a distribution board
It can be fed from either top or bottom and mounted in any orientation, which simplifies wiring in tight enclosures.