In an embodiment a thermal protection device includes a housing, a varistor partly embedded in the housing, wherein the housing electrically insulates the varistor, and wherein the varistor includes a partly uninsulated contact surface, an inner wall of insulating material arranged adjacent to the contact surface of the varistor, a window in the inner wall configured to allow an electrical connection of the contact surface of the varistor in an operational state of the thermal protection device and a moveable insulation block configured to cover the window in the inner wall to insulate the varistor in a region of the window of the inner wall in a fault state of the thermal protection device.