What it is and what it does
The Siemens SENTRON 5SU9356-1CS10 is an RCD-operated circuit breaker — an RCBO — combining overcurrent protection and residual current detection in a single 1P+N package. It is rated 10 A at AC with a C tripping characteristic, meaning it handles moderate inrush from motor or lighting loads without nuisance tripping, while still clearing short circuits up to 6 kA per EN 60898 and 10 kA per IEC 60947-2. The C-curve is the standard choice for general-purpose industrial and commercial circuits where the connected load has a mild starting surge.
Current derating and ambient limits
The full 10 A rating holds at 30 °C ambient. Above that, derate linearly: 9.4 A at 40 °C, 9.1 A at 45 °C, 8.7 A at 50 °C, and 8.1 A at 55 °C. The operating ambient range is -25 to +45 °C, so at the upper end you are already at 9.1 A continuous — factor that into panel loading if the enclosure runs warm. Storage range is -40 to +75 °C, which is wider than the operating range; that limit governs handling and shelf life, not running conditions.
Mounting and wiring
The 5SU9356-1CS10 occupies 2 width units (36 mm) on a DIN rail, with an installation depth of 70 mm and overall depth of 77 mm. It accepts solid or stranded conductors from 0.75 mm² up to 35 mm² — that covers everything from a 1.5 mm² lighting circuit to a 10 mm² feeder. Mounting position is any, and the supply can enter from either top or bottom, which simplifies panel layout. Touch protection is built in, and the IP20 rating applies once the distribution board is installed with conductors connected.