Abstract: Electronic power system is connected at an input to an electrical supply cable (24) and at an outlet to a conductive cable (17) connected to a system of current transmission, the whole of the device being adapted to be buried in the ground in a concrete box (1) such that the current transmission system will be able to transmit a current to an electrical machine such as an automobile that parks above it to receive a battery charge. A sealed metallic receptacle (2) in the form of a box filled with heat transfer liquid, is provided, a sealed compartment being located below the bottom (2a) of the latter box, in which is disposed the electronic power system of which at least one electronic power component is directly fixed to the lower surface of the bottom of the latter box, so as to give rise within the receptacle to stirring of the heat transfer liquid by thermosiphon effect.