The Siemens 5SU9106-1KK32 is a 1P+N RCD-operated circuit breaker (RCBO) from the SENTRON 5SU9 family, combining overcurrent and residual current protection in a single 18 mm wide module.
Thermal derating and conductor sizing
The 32 A rating holds only at 30 °C ambient. At 40 °C it derates to 30.08 A, at 45 °C to 29.12 A, at 50 °C to 27.84 A, and at 55 °C to 25.92 A. If your panel runs warm — typical for a crowded enclosure — size the upstream protection and load accordingly. The terminals accept solid or stranded conductors from 0.75 mm² up to 35 mm², which covers everything from a 1.5 mm² lighting circuit to a 10 mm² feeder. Power dissipation is a modest 0.75 W maximum, so heat buildup in a dense row is manageable.
Feed from top or bottom, which simplifies wiring in retrofit panels where the busbar is already landed. Touch protection is built in (fingertip-safe terminals per the spec). IP20 rated once installed with conductors connected, so it belongs inside a distribution board, not in a wet location.