What it is — and what the ratings mean for fit
The Siemens 5SU9356-1KK16 is a SENTRON RCD-operated circuit breaker (RCBO) — a combined residual-current device and miniature circuit breaker in one unit. It protects a single-phase final subcircuit against overload, short-circuit, and earth leakage in one DIN-rail footprint. Rated 16 A at 30 °C with a C tripping characteristic, meaning it handles moderate inrush from motorized or capacitive loads (pumps, small compressors, lighting ballasts) while still clearing sustained overloads. The C-curve is the standard choice for general-purpose commercial and light-industrial branch circuits where the load isn't purely resistive. Breaking capacity is 6 kA per EN 60898 (the MCB standard) and 10 kA per IEC 60947-2 (the industrial breaker standard). The higher 10 kA figure governs when the device is applied as a circuit breaker in an industrial distribution board — it will safely interrupt a fault up to 10 kA without welding contacts or cascading failure upstream. The 1P+N configuration protects the live pole only; the neutral pole is switched but not protected. This is standard for single-phase final circuits where the neutral is not expected to see overload current.
Deployment context — where this part lands
Width is 36 mm (2 modular units), depth 77 mm. Supply can enter from top or bottom. Rated for overvoltage category III and pollution degree 2 — the typical environment inside a building's main or sub-distribution board. IP20 applies when installed in an enclosed distribution board with conductors connected, which is the normal case; the device itself is not rated for exposed or washdown locations. Ambient temperature range is -40 °C to 75 °C, but the current-carrying capacity derates above 30 °C: 15.04 A at 40 °C, 14.56 A at 45 °C, 13.92 A at 50 °C, 12.96 A at 55 °C. If the panel ambient runs hot (e.g., adjacent to a drive cabinet or in a roof space), size the upstream protection for the derated figure, not the 16 A nameplate.
Compliance documentation
The device carries ratings per EN 60898 and IEC 60947-2, which are the governing standards for MCB and industrial circuit-breaker performance in Europe and many other jurisdictions. Halogen-free and silicon-free construction supports compliance with RoHS and REACH material declarations — documentation is available from Siemens on request.