Construction of Reverse Bends for Horizontal Cable Trays

Reverse bends in horizontal cable trays allow the tray to change direction smoothly while maintaining cable support and clearance.

Understanding Horizontal Reverse Bends

A reverse bend is a horizontal bend that redirects a cable tray in the opposite direction, often used to navigate around obstacles or align with structural constraints. These bends can be fabricated for ladder, perforated, or wire mesh cable trays and can be made in any degree as required by the installation layout . They are essential for maintaining continuous cable support and avoiding sharp turns that could damage cables.

Fabrication Techniques

1. On-Site Fabrication: Wire mesh or basket-type trays can be bent live at the project site using tools like a bolt cutter. The cutter not only shapes the tray but also forms a protective zinc layer on cut ends, preventing corrosion. Rubber caps can be added for additional safety .
2. Pre-Fabricated Bends: Manufacturers provide horizontal bends in standard or custom sizes to match the tray width, depth, and type. These bends can be ordered in specific angles to suit the installation plan .
3. Offset Calculation: For precise reverse bends, it is important to calculate the horizontal offset. This involves determining the straight tray length needed between two bends to bypass obstacles. Tools like cable tray offset calculators use trigonometry and industry multipliers to provide cut marks and sloped section lengths, ensuring proper alignment and clearance .

Installation Considerations

• Clearance: Ensure adequate space for workers to assemble the tray and for tools like wrenches and drills. A safety margin of at least 50 mm (2 inches) is recommended .
• Bend Angle: Reverse bends can be fabricated in any angle, but common practice is to use 30°, 45°, or 90° increments for easier alignment and structural support .
• Support: Install hangers or brackets at both ends of the bend to maintain stability and prevent sagging.
• Material Compatibility: Verify that the bend type matches the tray type (ladder, perforated, wire mesh) and the load rating of the system .

Summary

Constructing reverse bends for horizontal cable trays involves selecting the correct bend type, calculating offsets, and ensuring proper support and clearance. Bends can be fabricated on-site for wire mesh trays or pre-ordered from manufacturers for ladder and perforated trays. Using offset calculators and following installation guidelines ensures a smooth, safe, and efficient cable routing system .