The Siemens 5SU9356-1KK40 is a 2-pole (1P+N) SENTRON RCBO — an RCD-operated circuit breaker that combines overcurrent and residual current protection in a single 36 mm wide module.
Rated IP20 once the distribution board is closed and conductors are connected; not for wet-area panel faces without a cover.
Thermal derating and environment
Full rating is 40 A at 30 °C. Above that, derate linearly: 37.6 A at 40 °C, 36.4 A at 45 °C, 34.8 A at 50 °C, 32.4 A at 55 °C. Humidity tolerance up to 95%.
