The Siemens 5SU1653-1KK20 is a SENTRON RCBO (residual current circuit breaker with overcurrent protection) rated 20 A with a C tripping characteristic, 1P+N poles, and a 4.5 kA breaking capacity per EN 60898. It combines overcurrent and residual current (AC type) protection in a single 36 mm wide unit (2 MW), saving a DIN-rail position compared to separate MCB+RCCD.
Mounting and wiring specifics
The 5SU1653-1KK20 occupies 36 mm on the DIN rail (2 width units) with a depth of 77 mm and an installation depth of 70 mm. The supply cord can enter from either top or bottom, which simplifies busbar placement and panel layout. Conductor range: solid or stranded 0.75 to 35 mm² — covers most final-circuit wiring sizes. IP20 rating applies only when the distribution board is installed and conductors are connected; treat it as a panel-internal device, not for exposed mounting. Storage range extends -40 to +75 °C. Mounting position any — no restriction for vertical or horizontal rail.
Current derating — don't ignore it
At 30 °C the RCBO is rated for 20 A, but at 40 °C it drops to 18.8 A, at 50 °C to 17.4 A, and at 70 °C to 14.6 A. The 6.6 W maximum power dissipation is the internal loss at rated load; factor it into enclosure thermal calculations.