The assembly includes an openworked cable raceway (11) having a base (15) and side walls (16), the assembly (10) being provided for installing along a ceiling, and including at least one curved elongated panel (12), the concave surface of which faces towards the cable raceway (11), which curved elongated panel (12) is fastened to the cable raceway (11) and envelops the outside of the cable raceway (11) in line with a single side wall (16) and in line with at least a portion of the base (15) starting from the side wall (16).