The Siemens 5SU1356-0KV16 is a combined residual-current device and miniature circuit breaker (RCD/MCB) — an FI/LS protector — in a single 1+N-pole module. It integrates Type AC earth-leakage detection at 30 mA with a B-curve overcurrent trip rated 16 A, all within a 70 mm wide housing.
The 70 mm width (D=70MM) means this unit occupies 4 standard 17.5 mm DIN-rail modules. The 1+N-pole configuration switches the phase conductor and provides a switched neutral — the neutral pole is not protected against overcurrent but is disconnected when the device trips. Verify the neutral bar arrangement in the distribution board: this unit requires a dedicated neutral connection that passes through the residual-current summation transformer.