A frame arrangement for use with an interior space-dividing wall system including portable upright panel assemblies. The frame arrangement includes upright post assemblies in supportive engagement with the floor and a cross members which extend laterally between adjacent pairs of the post assemblies. The cross member mounts thereon a cable trough which may be utilized to carry cabling and to support a power distribution assembly including electrical receptacles for providing the panel assemblies with electrical power. The cross member and cable trough are adapted to prevent rotation of the cable trough during insertion and removal of plugs or jacks from the receptacles.