The Siemens 5SU1156-1KV16 is a combined residual-current device and miniature circuit breaker (RCBO / FI/LS protector) in a single 1+N-pole module. The 10 mA rated residual operating current (IΔN) is sized for wet-location or medical-grade protection where a 30 mA device would not trip fast enough for the touch-voltage limit.
The C16A overcurrent characteristic (magnetic trip at 5–10× In) handles motor inrush from small pumps, compressors, and fluorescent ballasts without nuisance tripping, while the thermal element protects the 1.5 mm² or 2.5 mm² copper circuit. 70 mm depth matches standard DIN-rail enclosures; no oversize box needed.
Integration note
The 1+N-pole format occupies a single modular width; the neutral pole switches and is not solid-barred, so verify the neutral bar arrangement in the distribution board if retrofitting into an existing busbar system.