Middle crossbar of trapezoidal cable tray

The middle crossbar (rung) of a trapezoidal cable tray should follow IEC 61537/BS EN 61537 guidelines, typically spaced 150–230 mm apart, designed to support the cable load and maintain structural integrity.

Rung Spacing and Placement

For trapezoidal cable trays, the middle crossbars (rungs) are critical for supporting cables and maintaining the tray's shape. According to technical guides, a rung spacing of 6 to 9 inches (150–230 mm) is generally recommended, depending on the type and weight of cables being installed, as well as the tray width and material strength. This spacing ensures that cables are adequately supported, prevents sagging, and maintains the minimum bend radius for sensitive instrumentation or control cables.

Mechanical Strength Requirements

The crossbars must be designed to withstand the mechanical load of the cables, environmental factors, and any external pressure.

IE

C 61537 specifies that cable trays, including their rungs, should undergo load testing to verify structural performance under maximum expected loads. The material of the crossbars is typically steel, stainless steel, or aluminum, with appropriate corrosion protection depending on the installation environment.

Installation and Compliance

Crossbars should be securely welded or bolted to the tray side rails to prevent movement during installation or under load. Screwed connections, if used, should comply with ISO metric threads and withstand mechanical stresses without damaging cables. All components, including middle crossbars, must maintain electrical continuity if the tray serves as a grounding path.

Accessories such as bends, tees, or end closures should be supported at appropriate positions to avoid overloading the rungs.

Practical Considerations

For heavier cable loads, consider reducing rung spacing to increase support. Ensure that the crossbar design does not interfere with cable installation or maintenance. Verify that the tray and crossbars meet national or international standards (IEC 61537, BS EN 61537) for safety, corrosion resistance, and mechanical performance.

By following these guidelines, the middle crossbar of a trapezoidal cable tray will provide adequate support, maintain structural integrity, and comply with recognized standards.