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 generic guideline provided by The Cable Tray Institute indicates that cable trays should not be filled in excess of 40-50% of the inside area of the tray or of the maximum weight based on the cable tray specifications. The NEC provides specific and more detailed requirements for cable tray fill. • Ladder cable tray cannot pipe hazardous or explosive gases from one area to another as happens with conduit systems. 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. (B) Welding cables installed in dedicated cable trays; (C) Single conductors used as equipment grounding conductors; these conductors, which may be insulated, covered, or bare, shall be No.
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