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). 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. Although the type of cable and conductor is the determining factor in the fire behaviour of ducts and conduits, the choice of cable tray type and the installation of the latter in line with installation precautions are just as crucial. Cables are very rarely the source of a fire. Tray Type and Material Selection Indoor: Painted steel or galvanized trays. Outdoor: Hot-dip galvanized or. Electrical cable tray wall penetration firestopping Scope: Firestopping for busway, cable trays, cables, and trunking passing through walls in enclosed electrical installations. Where cables pass through shafts, walls, slabs, or enter electrical panels or cabinets, openings shall be tightly sealed. NEC Article 392 explains cable trays, their components, appropriate wiring methods for cable trays, and instances where they are and are not permitted for use.
