Converting ordinary cable trays to trapezoidal cable trays

Cable trays are not inherently trapezoidal, but trapeze hangers are commonly used to support them for optimal load distribution and installation flexibility.

Cable Tray Shapes and Types

Cable trays come in various forms, including ladder-type, trough-type, and solid-bottom trays. The tray itself is typically rectangular or U-shaped rather than trapezoidal, designed to accommodate the number and size of cables while allowing proper ventilation and heat dissipation. The choice of tray shape depends on the application, cable type, and environmental conditions.

Trapeze Hangers for Support

The term "trapezoidal" often refers to the trapeze hanger support method, not the tray shape itself. Trapeze hangers consist of two parallel rods or channels supporting the tray from the ceiling, forming a trapezoid-like structure when viewed in cross-section. This method provides several advantages: Even load distribution across the tray span, reducing sagging and stress on the tray material.

Flexibility in installation, allowing multiple trays to be suspended at different heights or angles. Ease of maintenance, as cables remain accessible from below without obstruction.

Installation Considerations

When using trapeze hangers or any support system: Ensure the tray is not overfilled, following NEC 392. 22 for maximum fill area to prevent overheating and maintain ampacity. Maintain proper spacing between hangers to support the tray's weight and the cables it carries.

Consider environmental factors such as corrosion, temperature, and vibration, which may influence material choice and hanger spacing.

Summary

While cable trays themselves are generally rectangular or U-shaped, trapezoidal support structures like trapeze hangers are widely used to suspend them safely and efficiently. This approach ensures proper load distribution, compliance with electrical codes, and ease of cable management in commercial and industrial installations.