The Siemens 5SU1356-1DA32 is a combined residual-current and miniature circuit breaker (RCBO) — an FI/LS protector in Siemens' 5SU series. It integrates ground-fault and overcurrent protection into a single 1+N-pole unit, sized for a 32 A C-curve thermal-magnetic trip and a 30 mA Type AC residual-current trip. The 6 kA breaking capacity suits it for final-subcircuit protection in residential and light commercial distribution boards where the prospective fault current stays at or below that level. The pig-tail connection on the neutral side simplifies wiring in a standard DIN-rail enclosure, provided the installer observes the manufacturer's torque and strip-length specification.
What the ratings mean for fit
The C-curve (32 A) means the magnetic trip operates between 5× and 10× rated current — 160 A to 320 A — so it tolerates the inrush of motor-driven loads like pumps or compressors without nuisance tripping, provided the branch circuit's starting surge stays within that band. The 30 mA residual-current element (Type AC) detects sinusoidal AC fault currents only; it will not reliably trip on pulsed DC or smooth DC fault waveforms, which limits its use to circuits where the load is purely AC (resistive heaters, incandescent lighting, standard induction motors). For variable-speed drives, LED drivers, or any load with rectification, a Type A or Type B RCD would be required. The 6 kA breaking capacity (Icn) is the short-circuit rating per IEC 61009-1. In a domestic or light commercial distribution board with a 6 kA prospective fault level at the outgoing terminals, this device clears a bolted fault without needing an upstream current-limiting fuse. If the supply transformer is close enough to push fault current above 6 kA, a limiting MCB or fuse upstream is necessary to keep the let-through energy within the RCBO's rating.
Deployment context
The 70 mm width and DIN-rail mounting profile mean it occupies a standard modular slot in a consumer unit or sub-distribution board. The pig-tail neutral connection requires landing the factory-attached lead on the neutral busbar.