The Siemens 5SU1424-7RC40 is a 2-pole RCBO (residual current circuit breaker with overcurrent protection) from the SENTRON series, combining a 40 A overcurrent trip with a 100 mA Type A residual-current device in a single 4-module-wide unit. It protects final circuits against both overload/short-circuit and earth-leakage faults, and the Type A characteristic means it detects pulsating DC residual currents as well as sinusoidal AC — needed on circuits with rectified loads like switched-mode power supplies or variable-speed drives. Rated 10 kA per EN 60898 and 15 kA per IEC 60947-2, the 5SU1424-7RC40 handles typical domestic and light-commercial fault levels. The higher IEC figure applies when the RCBO is used as a circuit breaker in industrial distribution; the EN figure governs its use as a household-type device. Either way, the 4 kV rated surge voltage (Overvoltage Category III) and 440 V insulation voltage keep it coordinated with standard panel gear.
C-curve and 100 mA residual — what they mean on the panel
The 100 mA residual sensitivity is a higher threshold than the 30 mA used for personal shock protection; it is selected for circuits where a degree of leakage is expected (long cable runs, equipment with built-in filters) and where the priority is fire protection and equipment damage prevention rather than direct touch protection. At 4 module widths (72 mm), it occupies two standard 18 mm slots more than a typical single-pole MCB, so factor that into the panel fill count.
Dimensions: 72 mm wide (4 module units), 90 mm high, 70 mm deep. The 70 mm installation depth matches the standard depth of most domestic and light-commercial distribution boards — no deep enclosure required.