Abstract: An electric ducting comprises, inside a metal protection casing in the form of a tubular conduit, a flat support which extends in the longitudinal direction of the casing, over the whole length thereof, and which is formed by extruding an electrically insulating plastic material. The support is provided with parallel grooves arranged side by side, in each of which a current conducting bar is housed flat. For the same flat grooved extruded support, the conducting bars corresponding to different current ratings have the same general U-shape whose legs and base have respectively the same outer height and the same outer width whatever the current rating, only the thickness of the U-shaped bar varying as a function of the current rating.