Cable tray support quantity can be calculated using a simple formula: Support Quantity = Total Length ÷ Support Spacing + 1 20 ÷ 2 + 1 = 11 supports In a typical project, a 20-meter cable tray with 2-meter spacing requires 11 supports. A cable support system consists of cable support lengths and system components, such as cable support fittings, support elements, mounting elements and system acces-sories. Cable ladder systems and cable tray systems shall be manufactured in accordance with BS EN 61537, channel support. For straight lengths; dunnage should be placed no closer than 1/4 of the tray from its ends if using 2 supporting points. For 6 meter tray that would be approximately 1. Clause 522-08-04 Where conductors or cables are not supported. The standard NEMA lengths for cable tray are 12, 20, 24 and 30-feet, although some manufacturers like Eaton offer cable tray in lengths up to 40 feet. Selecting a cable tray length is based on several criteria, including: The required load that the cable tray must support.
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