To find the size of the cut in the tray, you divide the distance between the sets by the width of the tray. For instance, 1500 divided by 600 equals 2. That gives the wanted cuit size. Calculate horizontal, vertical, or compound cable tray offsets based on bend angle, offset distance, and available installation space. Then, select a standard tray fitting (300mm, 450mm, etc. Pre-fab vs Field Bent: For standard offsets (6, 12, 18 in at 45°), use manufacturer pre-fabricated offset fittings to save. The NEC requires that cable trays must be supported by members at an interval specified by the cable tray manufacturer, but not more than 5 feet for horizontal runs to support the weight of the cables and other loads. The NEC has a requirement for ladder-type cable trays.
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