The molding (1) has a key slot (2) with longitudinal corrugations, which key slot (2) is inclined at an acute angle to the wall surface. The connecting bracket (4) is a plate and one end of the plate has a shoulder terminated with a flexible tenon (6) with a free end pointed towards the molding, and the other end of the connecting bracket (4) is terminated with a spacer flange (7). Surfaces of the elastic tenon (6) of the connecting bracket have hooks with a triangular profile and the connecting bracket (4) has at least one shelf ledge (9) which supports cables. The molding has a form of a covering, preferably from poly vinyl chloride, which forms a skeleton profile divided with ribs (21) into chambers (28, 29, 30, 31) and the molding has a longitudinal protrusion (19), basically parallel to the wall surface, forming with the chamfered end of the molding an inverted V shape and the protrusion cooperates with the beaded edge (20) of the spacing flange of the connecting bracket (4).