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 NEC has a requirement for ladder-type cable trays. The rungs cannot be more. Clearances: Maintain at least 12 inches of vertical clearance above trays for installation and maintenance access (2026 NEC update). Separation of Electrical and Instrumentation Cables Electrical on Top, Instrumentation Below: Typically, electrical trays are positioned above instrumentation trays. It is used in EPC projects for basic engineering, detailed engineering, making the bill of quantities (BOQ), and. In vertical trays, cables shall also be secured at intermediate locations as necessary to keep all cables completely within and secured to the tray.
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