The invention relates to an electrical protective circuit (100), comprising: an input terminal (101), to which a voltage can be applied; a closable switching path (103), which is arranged parallel to the input terminal (101), wherein a controllable switch (105) for closing the closable switching path (103) is connected in the closable switching path (103); a sensing device (107), which is connected to the input terminal (101) and is designed to sense an error voltage present at the input terminal (101), wherein the sensing device (107) is designed to transmit a control signal to the controllable switch (105) to close said controllable switch (105) if an error voltage is sensed, in order to close the closable switching path (103); and an energy supply device (109), which is connected in parallel to the closable switching path (103) and is designed to convert a dropping voltage across the closed controllable switch (105) into a supply voltage and to apply the supply voltage to the sensing device (107).