Learn NEC Article 392 requirements for cable trays, including grounding, bonding, fill capacity, and compliant installation for power, control, Ethernet, and. Cable Tray Fill Capacity Rules The NEC sets clear limitations on cable tray fill to ensure safety, performance, and long-term reliability. Tray fill requirements are determined by several factors, including cable diameter, whether the cables are single-conductor or multi-conductor, the width and. This standard specifies the requirements for nonmetallic cable trays and associated fittings designed for use in accordance with the rules of the Canadian Electrical Code (CEC) Part 1, and the National Electrical Code® (NEC). Covers construction and test requirements for. The primary rulebook used in the safe use of cable trays is NEC Article 392. This is a description of how to select, install, and support these metal or plastic frames, on which electrical wires are installed. Introduction and. The National Electrical Manufacturers Association (NEMA) also publishes three consensus standards that apply to the proper manufacture and installation of cable trays: ANSI/NEMA-VE 1-1998, Metal Cable Tray Systems; NEMA-VE 2-1996, Metal Cable Tray Installation Guidelines; and NEMA-FG-1998. Cable Tray Support Span: The distance between supports is a critical calculation. The cable tray support span must be determined based on the manufacturer's load capacity chart and the total anticipated weight of the cables.