A permanent short-circuit device includes an enclosure with a first and second fixed electrically conducting body, each connected to a respective conductor leaving the enclosure, the first and second bodies body each having a first and a second surface on opposite sides of the respective body, where the first surface of the first body faces the first surface of the second body and is separated therefrom by a gap with width d and the second surface of the first body is provided with explosives connected to a detonator for deforming the first body towards the first surface of the second body such that the first surface of the first body crosses the gap and galvanically connects to the first surface of the second body.