Spacing of Aluminum Alloy Cable Tray Crossarms

Standard aluminum alloy ladder cable trays typically use crossarm (rung) spacing of 6, 9, 12, or 18 inches, depending on load and cable type, with long-span trays requiring supports every 40 feet for heavy-duty applications.Standard Rung SpacingAluminum ladder-type cable trays consist of two longitudinal side rails connected by transverse members (rungs). Common rung spacings are 6", 9", 12", and 18", measured from the center of one rung to the center of the next . The choice of spacing depends on:Cable size and type: Heavier or larger cables may require closer spacing to prevent sagging.Load requirements: Higher loads may necessitate shorter spans between rungs.Tray width: Wider trays may need closer rung spacing to maintain structural integrity.For ventilated bottom trays, maximum opening is typically 52 mm, while solid bottom trays often use 12" spacing .Long-Span Aluminum Cable TraysFor long straight runs, such as industrial or commercial installations, extruded aluminum alloy trays with H-beam side rails can span up to 40 feet (12.2 meters) between supports . These long-span trays reduce the number of supports required, but the rung spacing within the tray still follows standard 6", 9", or 12" centers depending on the load and tray width. Deflection calculations are based on simple spans, and continuous spans can reduce deflection by up to 50% .Installation and Compliance ConsiderationsSupport spacing: Standard support intervals for typical trays are shorter than long-span trays, often every 8–10 feet, depending on load and manufacturer recommendations .Welding or fastening: Rungs are either heliarc welded, resistance welded, or mechanically fastened to side rails, ensuring structural integrity .Standards: Aluminum cable trays should comply with NEMA VE-1, NEC Article 392, and UL classifications for safety and performance .SummaryRung spacing options: 6", 9", 12", 18" (center-to-center)Long-span support: Up to 40 ft (12.2 m) between supports for heavy-duty aluminum traysTray width and load: Determine exact spacing based on cable type, tray width, and load requirementsCompliance: Follow NEMA, NEC, and UL standards for installation and structural safetyBy selecting the appropriate rung spacing and support intervals, aluminum alloy cable trays can safely carry electrical cables while minimizing sag and deflection.