RCBO for final-circuit protection — 6 A C-curve, 1P+N
The Siemens 5SU1353-7KK06 is a SENTRON RCBO (residual current operated circuit breaker with integral overcurrent protection) in a 1P+N configuration. It combines a C-curve miniature circuit breaker for the phase conductor with a residual current detection module that also disconnects the neutral. Rated 6 A at 30 °C and 230/240 V AC, 50 Hz, it is sized for lighting, small appliance, or general-purpose socket circuits in residential and light commercial distribution boards. The C-curve tripping characteristic (magnetic release between 5× and 10× In) handles moderate inrush from small motors or capacitive loads without nuisance trips, while still clearing short circuits fast enough for cable protection. Breaking capacity is 4.5 kA per EN 60898 for domestic installations and 25 kA per IEC 60947-2 for industrial panels where higher prospective fault current is expected — the higher figure gives the panel designer headroom for coordination with an upstream MCCB or fuse. The residual current element is instantaneous type (no intentional delay), so it trips within 40 ms on a ground fault. Minimum test voltage is 195 V, meaning the test button functions reliably even on a lightly loaded phase. Supply can enter from either top or bottom, which simplifies busbar routing in a crowded enclosure.
Temperature derating and panel fit
Rated current is 6 A at 30 °C ambient, but the 5SU1353-7KK06 derates linearly as enclosure temperature rises: 5.7 A at 40 °C, 5.4 A at 50 °C, 5.1 A at 60 °C, and 4.62 A at 70 °C. In a sealed distribution board with multiple RCBOs ganged, the effective current per device drops — size the circuit load against the derated figure at the expected internal temperature, not the 30 °C nameplate. The device occupies 2 modular width units (36 mm) on a DIN rail, with a depth of 77 mm and an installation depth of 70 mm behind the panel face. IP20 rating applies once the distribution board is closed and conductors are connected — the front face is finger-safe, but the terminals are not touch-proof with the cover open. Mounting position is any orientation, which helps in tight retrofit enclosures where vertical or horizontal rail placement is the only option.