The Siemens 5SU1656-6KK25 is a SENTRON RCBO (residual current circuit breaker with overcurrent protection) in a 2-module-width housing. It combines a 25 A rated operational current with a 300 mA Type A residual current trip and a B tripping characteristic. Rated for 230/240 V AC at 50 Hz, it breaks fault currents up to 6 kA per EN 60898 and 15 kA per IEC 60947-2. The 1P+N configuration switches the neutral conductor.
What the ratings mean for fit
The 25 A rating and B curve mean this RCBO is sized for residential or light commercial final circuits supplying resistive or low-inrush loads — lighting, general-purpose sockets, small appliances. B curve trips at 3–5× rated current, so it clears short circuits quickly but avoids nuisance trips on moderate motor-start currents. The 300 mA Type A residual current element detects sinusoidal AC faults and pulsating DC faults, covering most modern electronics and variable-speed drives. The 6 kA breaking capacity per EN 60898 is the standard for domestic distribution boards; the higher 15 kA per IEC 60947-2 applies when the device is used in an industrial sub-distribution panel with higher prospective fault current. Overvoltage category III and pollution degree 2 confirm it is suitable for fixed installations in a building's main or sub-distribution board.
Panel integration
The 36 mm width occupies 2 modular units on a DIN rail, matching the standard 18 mm per module. Installation depth is 70 mm; total depth including the housing is 77 mm. Mounting position is unrestricted, and the supply cable can enter from either the top or bottom. The IP20 rating applies once the distribution board is installed and conductors are connected. Touch protection is integrated.