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). A rung spacing of 6 to 9 inches (150 to 230 mm) is preferable when the cable tray cont d for instrumentation and control applications that require additional protec eferred to support and protect numerous small. In all instances cables utilized within a cable tray system should be UL listed and marked as cable tray rated. This is a description of how to select, install, and support these metal or plastic frames, on which electrical wires are installed. Generally speaking raceway completely encloses the cable inside of it. This is a critical distinction because it means the requirements for the cable contained in raceway is. 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. Unlike standard electrical cables, tray cables feature enhanced insulation and jacketing to withstand mechanical stress and exposure to oil, sunlight.
