An electric circuit device for detecting a closed switch contact of a switching-off device as well as for recognizing a protective ground conductor interruption in a one- or multiphase electric supply line having active conductors (L1, L2, L3, N) and a protective ground conductor, having a residual current monitoring module (RCMB) which comprises a RCMB control for evaluating a measuring signal supplied by a measuring current transformer and for generating a first switching-off signal (S4a), the measuring current transformer capturing a residual current flowing on the supply line, and having a system control for generating a second switching-off signal (S4b), the switching-off device being configured for separating the active conductors (L1, L2, L3, N) and comprising a signal input for receiving the first switching-off signal (S4a) and the second switching-off signal (S4b), and the system control being connected to the RCMB control of the residual current monitoring module (RCMB) for receiving a fault signal, characterized in that the RCMB control comprises a fault current control unit for generating a control signal pattern which controls a first electronic switch unit for switching an artificial passive fault current flowing via one or more of the active conductors (L1, L2, L3, N) and the protective ground conductor, the switched artificial passive fault current being settable such that it is detected as a residual current by the residual current monitoring module (RCMB) but does not trigger a fault current protective device installed in the supply line, the RCMB control comprising a signaling device which signals detecting the artificial passive fault current and thus the presence of the functional protective ground conductor as well as a mains voltage (UL1, UL2, UL3), and the RCMB control comprises a fault current comparator which compares a fault current progression detected by the measuring current transformer to the fault current progression expected due to the control signal pattern in order to reliably detect the switched artificial passive fault current. having a residual current monitoring module (RCMB) which comprises a RCMB control for evaluating a measuring signal supplied by a measuring current transformer and for generating a first switching-off signal (S4a), the measuring current transformer capturing a residual current flowing on the supply line, and having a system control for generating a second switching-off signal (S4b), the switching-off device being configured for separating the active conductors (L1, L2, L3, N) and comprising a signal input for receiving the first switching-off signal (S4a) and the second switching-off signal (S4b), and the system control being connected to the RCMB control of the residual current monitoring module (RCMB) for receiving a fault signal, characterized in that the RCMB control comprises a fault current control unit for generating a control signal pattern which controls a first electronic switch unit for switching an artificial passive fault current flowing via one or more of the active conductors (L1, L2, L3, N) and the protective ground conductor, the switched artificial passive fault current being settable such that it is detected as a residual current by the residual current monitoring module (RCMB) but does not trigger a fault current protective device installed in the supply line, the RCMB control comprising a signaling device which signals detecting the artificial passive fault current and thus the presence of the functional protective ground conductor as well as a mains voltage (UL1, UL2, UL3), and the RCMB control comprises a fault current comparator which compares a fault current progression detected by the measuring current transformer to the fault current progression expected due to the control signal pattern in order to reliably detect the switched artificial passive fault current.