Flat flanged covers should be used on all 3", 4” and 6” wide channel applications requiring covers. MP Husky offers a wide variety of cable tray covers to provide protection for the cables contained within the system from sunlight, environmental elements, dirt, debris, and falling objects. Covers are fabricated. 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. 6 (requirements for cable tray installations). These essential components: Example: Stainless steel covers meet NEC 392.