What this RCBO delivers for the panel schedule
The Siemens 5SU9406-1KK40 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. The 1P+N configuration protects the phase conductor and switches the neutral — the neutral pole is not protected, only switched.
Current derating and conductor sizing
At 40 °C it derates to 37.6 A, at 45 °C to 36.4 A, at 50 °C to 34.8 A, and at 55 °C to 32.4 A.
Integration into the DIN-rail panel
Width is 18 mm (1 width unit), depth 77 mm, installation depth 70 mm, height 125 mm. Supply can enter from either top or bottom, which saves wiring time when the busbar is on the opposite side. Touch protection is built in (IP20 with connected conductors in a closed distribution board). Overvoltage category III suits fixed-installation mains connection.