Abstract: In order positively to ground a structure such as a pole carrying an electric line, which is not sufficiently grounded and therefore presents risks of electrocution in the event of untimely connection with the line, a voltage detector is provided, interposed between the structure and the ground, a fuse cartridge is connected to the voltage detector, said cartridge comprising a plunger which, when the cartridge is functioning, triggers a short-circuit switch grounding the structure via large-section conductors. A surge arrester is associated with the system which, during the very short instant necessary for the assembly constituted by the voltage detector and fuse cartridge and switch to function, maintains the voltage of the structure at a limited value not presenting any risk of instantaneous electrocution.