What it is and what it does
The Siemens SENTRON 5SU9353-1KK16 is a 2-pole RCD-operated circuit breaker (RCBO) — a combined overcurrent and residual-current device in a single 36 mm-wide module. It carries a 16 A thermal-magnetic trip (characteristic C) and a 30 mA residual-current trip, Type AC (sensitive to sinusoidal AC fault currents only). The 4.5 kA breaking capacity per EN 60898 covers standard domestic and light commercial distribution boards. Neutral switching is included, so the neutral pole opens and closes with the phase, which is required in some regional wiring rules.
Mounting and integration
Snaps onto a 35 mm DIN rail; occupies 2 modular width units (36 mm total). Depth is 77 mm, height 90 mm, installation depth 70 mm. Mounting position is unrestricted, and supply can enter from top or bottom. The IP20 rating applies only when the distribution board is installed with connected conductors — so it's not a standalone outdoor device. Touch protection is built in.