Load-bearing requirements for cable tray supports

Cable tray support systems must comply with standards like IEC 61537 or BS EN 61537, ensuring they can safely bear cable loads, environmental forces, and mechanical stresses.

Key Standards

IEC 61537 is the internationally recognized standard for metallic cable tray systems, covering construction, testing, and performance requirements. It specifies that cable trays must withstand the weight of cables, environmental loads (wind, snow, ice), and external mechanical forces, while maintaining electrical continuity and corrosion resistance . In the UK, BS EN 61537 aligns with IEC 61537 and provides similar guidance for cable ladder and tray systems .

Load-Bearing Considerations

1. Tray Strength and Load Capacity Cable trays must support the combined weight of installed cables and any additional environmental loads. Load capacity depends on tray type, material (steel, stainless steel, aluminum), and design. Ladder trays for large power cables typically require wider rung spacing (9–18 inches) to maintain proper bending radii, while smaller control cables can use closer spacing (6–12 inches), .
2. Support Span The distance between supports significantly affects tray strength. Typical spans are:
   • Short span: 6–8 feet
   • Intermediate span: 10–12 feet
   • Long span: 14–20 feet
   • Extra-long span: 20–40 feet for outdoor or road-crossing installations . Support spacing must be chosen based on tray type, cable load, and environmental conditions.
3. Splice Plates and Tray Length Splice plates connect tray sections and should generally be limited to one per support span. Tray lengths must be equal to or longer than the selected support span to ensure structural integrity .
4. Environmental and Mechanical Loads Cable trays may be exposed to wind, snow, ice, or seismic forces. Standards require trays to be designed to withstand these loads without excessive deflection or failure .
5. Installation Guidelines
   • Only use components designed and tested together as a system.
   • Avoid using trays as walkways or for supporting personnel.
   • Ensure proper alignment and secure fastening to walls, ceilings, or structural supports .

Practical Recommendations

• Consult the manufacturer's load tables for specific tray types and materials.
• Consider corrosion protection for outdoor or chemical environments.
• Verify cable bending radii to prevent damage.
• Ensure compliance with local electrical codes and safety regulations. By adhering to these standards and guidelines, cable tray systems can safely support electrical and communication cables while minimizing the risk of mechanical failure, cable damage, or safety hazards .