The inventive rack positioning assembly for an electric panel comprises a vertical busbar (J2) for distributing electric current to electric appliances, said busbar comprising several bars, which are positioned in a same vertical plane and on which it is provided to connect racks of the electric panel, and several rack positioning modules (20), which are positioned above one another and which surround the bars of the vertical busbar. The positioning modules (20) comprise means (50) for increasing the insulation distance between the bars at the interface between two successive modules, that insulation distance corresponding to the length of the electric creep path between the bars.