Due to their exposure to the open air because of the cable trays, the wires contained within need a very durable outer covering. The regulations dictate that the cables must either be Type TC (also known as Tray Rated) or must be metal-armored (Type MC). The use and installation of cable trays is covered by legally enforceable OSHA regulations in 29 CFR 1910. In addition, this document contains several references to provisions of the National Electric Code. 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. You should consider it as a series of instructions that make the buildings resistant to. NEC Article 392 governs cable tray systems. Grounding and bonding are mandatory for metallic trays. Tray fill limits must be calculated properly. At the same time, try to install the device under a canopy to. en completely installed, without damage either to conductors or structural system use maintain spacing or to keep cables in place when the tray is ect the minimum bend ra-dius for cables as they exit the bottom of the cable tray.