The combined protective switch is mainly used in electrical installations of buildings, for personal, overload and short circuit protection. It is especially suitable for electrical protection of rooms with increased safety requirements. The current transformer of the protective switch, namely the magnetic quick breaker and the bimetallic, thermal, residual current breaker are placed in the same box. It breaks the circuit of the protected device only in one pole. The device is equipped with optical display for signaling the operational state: the red color marks the “ON” state of the switch. Correct operation of the device can be controlled by pushing the “T” test button. The test should possibly be effected monthly.