What is cable trayin construction?

Conduit encloses conductors in a closed tube that wires are pulled through; cable tray is an open structure that cables are laid into and secured. Tray wins where dozens of circuits share a route, because adding or rerouting a cable does not require pulling through a closed raceway, which is why data centers and industrial plants standardize on it. The cables themselves must be rated for tray installation.

Ladder tray (two side rails with rungs) is the standard for power feeders. Ventilated trough and solid bottom trays support smaller cables continuously, and wire mesh basket tray is the lightweight choice for structured cabling and low voltage pathways. Each comes in standard widths, commonly 6 to 36 in, in steel, aluminum, or stainless, and the spec assigns a load class that the supports must match.

Take off the straight tray in lf by width and type from the plan routes, including the vertical risers the plan view hides. Then count fittings (horizontal and vertical elbows, tees, crosses) as each items, supports at the spacing the spec and load class require, and add covers, dividers, and grounding hardware where called out. On fitting-dense routes the each-count items can approach the cost of the straight footage.