Never exceed the manufacturer's recommended distance between supports. Strategic Support Placement: Install supports within 2 feet (600mm) of every fitting (bends, tees, crosses) and on both sides of any expansion joint. This ensures the system remains rigid where mechanical stress. The National Electrical Code (NEC) covers many aspects of cable tray supports and fittings. The National Electrical Code is a set of principles designed to promote public safety and welfare, as well as safeguard public health by regulating the design and operation of electrical facilities and. The primary rulebook used in the safe use of cable trays is NEC Article 392. This guide covers the critical steps, from selecting the right electrical cable tray and performing accurate cable fill. Cable trays can be used as a support system for various wiring methods, including service conductors, feeders, branch circuits, communications circuits, control circuits, and signaling circuits (392. Cable trays are used not just in industrial establishments. The tray test is for the designated load and a 200# dead load in midspan.