Abstract: The invention concerns a device comprising two conductive spaced apart components (3, 4) and a blade (5) in the form of a conductive segment mobile between a position closing the circuit wherein it is in contact with the two conductive components and a position opening the circuit, wherein it is spaced apart from said components. The blade is mounted locked in translation on a rod (7) axially mobile in the box between a retracted position in the box wherein the blade (5) is in contact with the conductive components and a projecting position wherein the blade is spaced apart from the conductive components, means being provided to maintain the rod stable in those two positions.