What it is and what it does
The Siemens 5SU1356-0KK32 is a 2-pole SENTRON RCBO — a combined residual-current circuit breaker with overcurrent protection — rated 32 A at 30 °C with a B-curve tripping characteristic and AC-type residual-current sensing. It breaks fault currents up to 6 kA per EN 60898 and 15 kA per IEC 60947-2, so it handles both the domestic-standard and industrial-standard short-circuit ratings in one unit. The AC-type residual-current detection means it trips on sinusoidal AC earth faults — the common type in resistive heating, lighting, and motor circuits without VFDs or phase-angle control.
Temperature derating — the real-world current limit
The 32 A rating holds at 30 °C ambient. At 40 °C it derates to 30.4 A, at 50 °C to 28.8 A, and at 70 °C to 24.64 A — so in a warm panel or summer enclosure, the actual continuous load limit is lower than the label number.
Mounting and panel fit
Width is 36 mm (2 modular-width units), depth 77 mm, installation depth 70 mm. Mounts in any position on DIN rail; supply can enter from top or bottom. Touch protection is built in. IP20 rating applies when installed in a distribution board with connected conductors — standard for enclosed panelboards, not for open wet-area mounting.