Only approved tray-rated cables should be installed. Grounding and bonding are mandatory for metallic trays. Tray fill limits must be calculated properly. This is a description of how to select, install, and support these metal or plastic frames, on which electrical wires are installed. You should consider it as a series of instructions that make the buildings resistant to. Use perforated trays or wire mesh trays to improve airflow. Here is the summary of the main points found in NEC Article. If not designed and installed properly, wiring inside cable trays may pose hazards such as fire, electric shock, and arc-flash blast events. Cable trays can be part of a planned cable management system to support, route, protect, and provide a pathway for cable systems. Power, low voltage control. Poorly fitted trays may serve as a fuse in case of a short or a top chimney in case of a fire.