The Siemens 5SU1356-0DA40 is an FI/LS protector (RCBO) combining residual current and overcurrent protection in a single 1+N-pole unit. It is Type AC, meaning it detects sinusoidal AC fault currents only — suitable for circuits without rectified or pulsed DC loads. The B-curve characteristic trips at 3–5× rated current, protecting wiring and loads against short-circuit and overload in residential or light commercial final circuits.
What the ratings mean for fit
Rated at 40 A with a 30 mA residual sensitivity, this unit protects a single-phase circuit up to 40 A while providing personal protection against earth faults. The 6 kA breaking capacity (Icn) is the short-circuit rating per IEC 61009-1 — adequate for domestic and light commercial distribution boards where the prospective short-circuit current stays under 6 kA. The D=70 mm width (4 module spaces) fits standard DIN-rail enclosures; the pig-tail neutral connection simplifies wiring in pre-assembled consumer units.