Vehicle electrical system, having: - at least two electrical system branches (BZ2, BZ3) which are electrically connected to each other via a positive voltage-side current path and each having at least one electrical device (L2, L3); - a disconnecting switch arrangement which is electrically connected in the current path between the two electrical system branches (BZ2, BZ3) and, in the event of a critical state in one of the two electrical system branches (BZ2, BZ3), is configured to interrupt a current flow via the current path; - wherein the disconnecting switch arrangement has a first controllable switch unit and a series circuit of a second controllable switch unit and an overcurrent protection unit, wherein the first switch unit and the series circuit are electrically connected to each other in parallel in the current path between the two electrical system branches (BZ2, BZ3); - wherein the disconnecting switch arrangement also has a control unit for actuating the disconnecting switch arrangement, which is connected in a signal-carrying way on its control signal output side to the first switch unit and the second switch unit, characterised in that the disconnecting switch arrangement is configured, in an idle mode of the vehicle electrical system, to switch the first switch unit into an open, current-disconnecting switching state and to switch the second switch unit into a closed, current-carrying switching state; - wherein the overcurrent protection unit is further configured, in the idle mode and in the event of an overcurrent in the series circuit, to interrupt the current flow via the series circuit. - at least two electrical system branches (BZ2, BZ3) which are electrically connected to each other via a positive voltage-side current path and each having at least one electrical device (L2, L3); - a disconnecting switch arrangement which is electrically connected in the current path between the two electrical system branches (BZ2, BZ3) and, in the event of a critical state in one of the two electrical system branches (BZ2, BZ3), is configured to interrupt a current flow via the current path; - wherein the disconnecting switch arrangement has a first controllable switch unit and a series circuit of a second controllable switch unit and an overcurrent protection unit, wherein the first switch unit and the series circuit are electrically connected to each other in parallel in the current path between the two electrical system branches (BZ2, BZ3); - wherein the disconnecting switch arrangement also has a control unit for actuating the disconnecting switch arrangement, which is connected in a signal-carrying way on its control signal output side to the first switch unit and the second switch unit, characterised in that the disconnecting switch arrangement is configured, in an idle mode of the vehicle electrical system, to switch the first switch unit into an open, current-disconnecting switching state and to switch the second switch unit into a closed, current-carrying switching state; - wherein the overcurrent protection unit is further configured, in the idle mode and in the event of an overcurrent in the series circuit, to interrupt the current flow via the series circuit.