Which standard should be used to calculate the thickness of cable trays

IEC 61537 is the primary standard used to determine the mechanical strength and material thickness of cable trays.

Overview of IEC 61537

IEC 61537 is the internationally recognized standard for metal cable tray and ladder systems, covering steel, stainless steel, aluminum, and other metallic materials . It specifies construction requirements, testing methods, and performance parameters, including the safe working load (SWL), uniformly distributed load (UDL), and span between supports, which directly influence the required tray thickness . Compliance ensures that trays can safely support cables, resist environmental factors, and maintain electrical continuity.

Key Considerations for Thickness Calculation

1. Mechanical Strength: The tray must withstand the weight of cables and external forces. IEC 61537 provides load testing methods to validate tray strength, which are used to determine the minimum material thickness required for a given span and load .
2. Span and Support Spacing: The distance between support devices affects deflection and stress. Longer spans or higher loads require thicker tray material to maintain structural integrity .
3. Tray Type and Material: Different tray types (solid-bottom, ventilated, ladder) and materials have varying strength characteristics. The standard provides guidance on how these factors influence thickness and load capacity .
4. Environmental Conditions: Corrosive or high-temperature environments may require thicker or coated materials to ensure durability and compliance with safety requirements .
5. Manufacturer Specifications: IEC 61537 allows manufacturers to declare SWL and recommended thicknesses for each tray type and width. These values are verified through testing and can be interpolated for intermediate sizes .

Additional Guidelines

• In the U.S., NEC Article 392 governs cable tray installations, but it primarily addresses installation practices rather than material thickness .
• Calculations should consider tray fill, cable grouping, and expansion margins to ensure safe and efficient cable management .
• Using a cable tray sizing calculator based on IEC 61537 can standardize thickness and width selection, reducing the risk of overloading or deflection .

Conclusion

For calculating the thickness of cable trays, IEC 61537 is the authoritative standard, providing detailed guidance on mechanical strength, load testing, and material requirements. Engineers should combine this standard with manufacturer load tables, span considerations, and environmental factors to determine the appropriate tray thickness for safe and compliant installations .