Rated protection for a single-phase final circuit
The Siemens 5SU1354-1LV20 is a combined residual-current device and miniature circuit breaker (RCBO) — an FI/LS protector — in a 1+N-pole form factor. It carries a 30 mA trip sensitivity (Type AC for sinusoidal AC fault currents), a 10 kA breaking capacity, and a C-curve 20 A overcurrent release. That C-curve means it handles moderate inrush from motorised or capacitive loads without nuisance tripping, while the 30 mA residual-current element covers personnel protection for socket-outlet circuits and wet-area final subcircuits.
Where this fits in the panel
The 5SU1354-1LV20 snaps onto a standard 35 mm DIN rail inside a distribution board or sub-distribution enclosure. The 70 mm depth (D=70MM) keeps it within the envelope of most domestic and light-commercial consumer units. The 1+N-pole format switches the line conductor and switches/isolates the neutral, which is the common arrangement for single-phase final circuits in TN and TT earthing systems.