Drop-Outs: Allow cables to exit the tray vertically to connect to equipment below. Cable Tray Supports: These include trapeze hangers, center-span supports, and wall brackets that anchor the entire system to the building structure (ceiling, wall, or floor). They are often installed on ceilings or walls. The layout includes determining the arrangement of cable trays, which act as physical support structures, as well as. Below are the key principles to guide the layout of E&I cable trays, focusing on practical, safety, and efficiency aspects. Separation of Electrical and Instrumentation Cables Electrical on Top, Instrumentation Below: Typically, electrical trays are positioned above instrumentation trays. Cable Trays: They are suitable for long, straight runs where a large number of wires are present.