What it is and what it does
The Siemens 5SU1654-1RC16 is a SENTRON RCBO — a combined residual-current circuit breaker and overcurrent protection device in one 2-module-wide package. It protects a single-phase final subcircuit against overload, short-circuit, and earth leakage in one unit. Rated at 16 A with a C characteristic tripping curve, it handles moderate inrush from motorised and fluorescent loads without nuisance trips. The 30 mA Type AC residual-current element catches sinusoidal AC earth faults — the standard choice for general-purpose socket circuits, lighting, and small appliances where no DC or pulsed fault content is expected. Breaking capacity is 10 kA per EN 60898 for domestic installations and 20 kA per IEC 60947-2 for industrial distribution boards — the higher figure gives selectivity headroom in a sub-distribution panel with a larger upstream device.
Panel fit and integration
Snaps onto a standard 35 mm DIN rail in any mounting position. Width is 36 mm (2 modular units), depth 70 mm behind the panel face — check gland-plate clearance if the enclosure is shallow. Supply can enter from either top or bottom, which simplifies busbar routing in a crowded distribution board. The IP20 rating applies once installed with conductors connected — the front face is touch-safe, but the terminals are not live-deck protected until wired.