Answer: Yes; cables are tied down in cable trays to keep the cables in the cable tray, to maintain spacing between cables, or to segregate or confine certain types of cables to specific locations. The last two items can also be accomplished with a solid fixed barrier. This publication is intended as a practical guide for the proper and safe* installation of cable ladder systems, cable tray systems, channel support systems and associated supports. This is a description of how to select, install, and support these metal or plastic frames, on which electrical wires are installed. The cable tray support span must be determined based on the manufacturer's load capacity chart and the total anticipated weight of the cables.