A method for interconnecting a first electric cable, constituted by a carbon fiber bundle enveloped in a first insulating sheath, with a second cable constituted by a metallic conductor enveloped in a second insulating sheath; the method provides for the removal of a first portion of the first sheath that covers a first end of the carbon fiber bundle, and the removal of a second portion of the second sheath that covers a second end of the metallic conductor, for an extension greater than that of the first portion. The method then provides for the spiral-like winding of the second end of the metallic conductor, starting from the first end of the first cable, until such metallic conductor affects the first sheath, and then the change of direction of advancement of the spiral defined by such second end, to provide at least one loop that covers the first sheath. The method then provides for the spiral-like winding of the metallic conductor in a direction of the first end of the bundle and the mutual alignment of the first and second cables, and then the addition of at least one layer of tin or other conductor or covering element to totally cover the second end of the metallic conductor.