What this RCBO is and where it fits
The Siemens 5SU1356-1KK06 is a SENTRON RCBO — a combined residual-current device and miniature circuit breaker in a single 2-module (36 mm wide) package. It protects a single-phase final subcircuit against both earth leakage and overcurrent/short-circuit, with a 1P+N pole arrangement (switched neutral). Rated 6 A at 30 °C with a Type C tripping characteristic (5–10× In magnetic release), it handles moderate inrush loads like small motors, lighting banks, and control transformers on 230/240 V AC 50 Hz supplies. Breaking capacity is 6 kA per EN 60898 for domestic/commercial distribution boards, and 25 kA per IEC 60947-2 for industrial panel applications — the higher figure gives selectivity headroom downstream of a larger upstream device. Overvoltage category III and pollution degree 2 suit fixed-installation environments inside enclosed distribution boards.
Dimensions and mounting — panel fit check
The 5SU1356-1KK06 occupies 2 modular width units (36 mm wide) on a DIN rail, with a depth of 77 mm and height of 90 mm. Installation depth is 70 mm. Mounting position is any orientation. Supply can enter from either top or bottom. IP20 rating applies once installed in a distribution board with conductors connected.
Thermal derating — what 6 A means at panel ambient
The 6 A rating is at 30 °C ambient. At 40 °C it derates to 5.7 A, at 50 °C to 5.4 A, and at 60 °C to 5.1 A. If your panel runs warm — common in crowded enclosures — size the circuit for the derated figure at expected ambient, not the 30 °C headline.