A multi-line supply unit for a vehicle control unit, including at least two supply lines each connected to a vehicle voltage source at the input and brought together at a common node at the output; and a protective device, including, in each of the supply lines, at least one first damping diode looped into the supply lines in the forward direction, between the vehicle voltage source and the node; and an operating method for such a multi-line supply unit. At least one switch element is looped into each of the supply lines, respectively, in parallel with the damping diode, respectively; an evaluation and control unit measuring and evaluating a line voltage at the inputs of the supply lines, respectively, and measuring and evaluating a reverse-polarity-protected supply voltage at the common node, and controlling the switch elements in the supply lines as a function of the evaluation, using corresponding control signals.