Cable trays are used as a substitute to open wiring systems, and are generally used for cable management in commercial and industrial buildings. They are particularly helpful in situations where changes to a wiring system are frequent, since new cables can be installed by setting them in the tray, instead of removing them through a pipe.
A ventilated cable tray has openings in the bottom of the tray, allowing for air circulation, water drainage, and dust reduction. A ladder cable tray has the cables supported by a cross bar, similarly to the steps of a ladder.
Ladder and ventilated cable trays may be covered to protect cables from falling objects, dust, and water. Tray covers for use outdoors or in dusty spots may have a summit shape to get rid of debris such as dust, ice or snow. Lighter cable trays are more appropriate in locations where a vast number of small cables are used, such as for telephone or computer networks.