Lamp test battery or locked element in a housing one of the poles is driven to a polar plug fixed externally disposed to the case while the other pole of the lamp is connected to a conductor shaped movably mounted on one side rod the side of the housing terminating in a polar plug whose main characteristic is that the shaped conductor rod (2) of flexible material is attached with its inner end to one end of a coil spring (3) loosely encircling the driver coil spring which tends to keep the driver inside the box with the other end attached to a fixed connection piece (4) with said other pole of the battery.
展开▼
