In general, vertical spacing for cable trays should be 30 cm (12 in), measured from the bottom of the upper tray to the top of the lower tray. The National Electrical Code is a set of principles designed to promote public safety and welfare, as well as safeguard public health by regulating the design and operation of electrical facilities and. 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. Here's what you need to know: Cable Types: Only use. Stacking trays is done either to avoid Tees or on a later modification where you can't just widen the supports easily, so you under/overbuild. 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.
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