Common types of cable trays include: Side rails connected by transverse rungs. Well suited for power and large control cables. Provides more continuous support for. Cable tray systems are engineered support structures designed to route, support, and protect insulated electrical cables used for power distribution, control, instrumentation, and communication. Because of its closed design, this type of tray should e used in applications where there is minimal risk of heat generation and buildup. Applications: Power plants and substations, Heavy. Although typically suspended from ceilings or affixed to walls, some cable tray systems are suitable for underfloor use.