RCD/MCB Combination Unit — Type AC, 30 mA, 6 kA
The Siemens 5SU1356-1DV25 is an FI/LS protector — a combined residual-current device (RCD) and miniature circuit breaker (MCB) in one 1+N-pole unit. It provides both earth-fault and overcurrent protection for a single-phase final subcircuit, sized at 25 A with a C-trip curve and a 30 mA residual-current sensitivity. The 6 kA breaking capacity covers domestic and light commercial installations where the prospective short-circuit current stays under that threshold.
What the Ratings Mean for Fit
The Type AC designation means it detects sinusoidal alternating residual currents only — suitable for circuits with resistive, capacitive, or inductive loads that do not generate pulsed or smooth DC fault currents. The 30 mA rated residual operating current (IΔn) provides additional fire protection and basic personal shock protection in standard installations. The C-curve (25 A rated current) is the magnetic trip characteristic: it allows inrush currents 5–10 times the nominal rating, so it handles motorized loads like pumps or compressors without nuisance tripping.
Panel Integration
The 70 mm depth (D=70MM) is the installed dimension from the DIN-rail mounting surface to the front of the device — check enclosure depth clearance before committing the BOM. The pigtail (PIG-TAIL) connection on the neutral side is factory-fitted; it simplifies wiring in a standard distribution board but means the neutral conductor is permanently connected, not looped through a separate terminal.