What it is and what it does
The Siemens 5SU9356-1CR50 is a 2-pole 1P+N RCBO — a combined RCD and MCB in one 36 mm wide module, part of the SENTRON 5SU9 family. It protects a single-phase AC circuit against overload, short-circuit, and earth leakage (AC type, 30 mA trip threshold). The C tripping characteristic means it holds magnetic trips for 5–10× rated current, so it's sized for motor and lighting circuits with moderate inrush, not pure resistive loads.
Ratings that matter for fit
Rated 50 A at 30 °C ambient, derated to 45 A at 50 °C — that thermal curve is what you size against if the panel runs warm. The 6 kA breaking capacity per EN 60898 covers most domestic and light commercial service-entrance faults; the 10 kA per IEC 60947-2 gives headroom for industrial panelboards with higher prospective fault current. Mounts in any position, feed from top or bottom, with an installation depth of 70 mm plus the 77 mm overall depth for wiring clearance. Terminal accepts solid or stranded conductors from 0.75 to 35 mm² — enough for the 50 A load on a 10 mm² cable. Power dissipation maxes at 1.5 W, so it won't cook adjacent devices in a densely packed sub-distribution board. Halogen- and silicon-free construction matters if this panel lives in a clean room or a zone where off-gassing during a fault could contaminate optics or electronics.
Panel integration notes
Occupies 2 width units (36 mm) on a DIN rail. The IP20 rating applies when installed in a distribution board with conductors connected — so it's not for wet or outdoor use without an enclosure. Overvoltage category III means it's rated for fixed installation downstream of the service entrance, not for plug-in equipment. Touch protection is built in, so no extra finger-safe shrouds needed.