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. Where cables pass through shafts, walls, slabs, or enter electrical panels or cabinets, openings shall be tightly sealed with firestopping materials in accordance with. When cable trays pass through walls from a normal environment into a fireproof or explosion-proof environment, appropriate sealing devices should be installed on the wall. Each cable tray system must be complete before cables are installed and must be exposed and accessible, except where extended transversely through partitions and walls, or vertically through platforms and floors in wet or dry locations. Where installed through walls or floors, cable trays and. When a cable tray passes through walls, floors, or ceilings, special precautions are needed: Fire-Resistant Sleeves: Use fire-rated sleeves or conduit to protect the cables where they penetrate walls or floors.
