The Siemens 5SU1353-1KL20 is a 1P+N RCBO from the SENTRON 5SU1 series, combining overcurrent and residual current protection in a single 36 mm wide module (2 width units). It is rated 20 A with a C tripping characteristic and a 4.5 kA breaking capacity per EN 60898, meaning it handles moderate inrush from motor or lighting loads while providing fault current interruption up to 4.5 kA. Rated current derates with ambient temperature: 20 A at 30 °C, dropping to 14.6 A at 70 °C (–), so if the panel runs hot, factor that into the load schedule.
IP20 applies only when the distribution board is installed and conductors are connected; the RCBO itself is not rated for exposed or washdown locations.
The C-curve means magnetic trip occurs at 5 to 10 times rated current (100–200 A for this 20 A unit), which is typical for circuits with motor or transformer inrush. Energy limiting class 3 indicates it lets through relatively low let-through energy during a fault, which helps with downstream coordination.