A method for protecting an electrical low-voltage circuit for a protective switching device. A mechanical break contact unit, which is switched by opening or closing contacts for current flow in the low-voltage circuit, and an electronic interrupter, which is switched by semiconductor-based switching elements into a high-impedance state or a low-impedance state of the switching elements, are connected in series. If the level of current in the low-voltage circuit exceeds a current threshold value, prevention of current flow through the low-voltage circuit is initiated by high-impedance switching of the electronic interrupter. When the electronic interrupter is high impedance or switched to high impedance, the level of current in the low-voltage circuit continues to be determined, and if a first residual current threshold value is exceeded, the contacts of the mechanical break contact unit are opened.