A protective device to be integrated into a high-voltage cable of a high-voltage on-board power supply includes a cut-out for interrupting at least one electrical conductor of the high-voltage cable in a fault scenario, a shielding element for forming a cable shield with a shielding conductor of the high-voltage cable, and a housing to be arranged between two high-voltage-cable sections of the high-voltage cable. In the housing, the cut-out and the shielding element are arranged, and the housing has contacts for connecting the cut-out to conductor sections of the at least one conductor and for connecting the shielding element to shielding-conductor sections of the shielding conductor. At least a part of the housing is capable of being non-destructively detached from the high-voltage-cable sections, in order to enable an exchange of at least the cut-out in the case of a defect of the cut-out.