Irregular Horizontal Bend of Cable Tray

Irregular horizontal bends in cable trays, such as 30° or 60° angles, can be fabricated on-site using precise measurements and offset calculations to ensure safe cable routing and compliance with standards.

Understanding Irregular Bends

Irregular horizontal bends occur when a cable tray must change direction at non-standard angles due to site constraints, obstacles, or specific layout requirements. Unlike standard 45° or 90° elbows, these bends require custom fabrication from straight tray sections to match the exact angle needed on-site .

Calculation and Fabrication

1. Determine the Bend Angle and Offset: Measure the required horizontal deviation and lateral shift. For offsets, two bends are typically used—one to move laterally and one to return parallel to the original path .
2. Use Bend Calculators: Tools like the Cable Tray Bend Calculator allow you to input the tray width, centerline radius, and offset dimensions to calculate the centerline arc length, chord, and setback distances. This ensures the bend meets NEC, IEC, or NEMA standards and accommodates the cable bend radius .
3. Site Fabrication: For angles such as 30° or 60°, the tray can be cut and bent on-site from straight sections. Ensure that the galvanization or protective coating is restored after cutting or welding to prevent corrosion .
4. Check Cable Bend Radius: Ensure the bend radius is sufficient for the cables being installed. For example, power cables often require a minimum bend radius of 12 times the cable diameter .

Practical Tips

• Straight Portion at Ends: Maintain at least 100 mm of straight tray at the ends of bends for proper assembly .
• Support Spacing: Ensure supports are spaced according to the tray type and load, especially near bends where cable weight may concentrate .
• Use Appropriate Tools: Round saws for cutting non-ferrous trays and bending tools for precise angles help achieve clean, accurate bends .
• Documentation: Record the fabricated angles and offsets for future maintenance and verification.

Summary

Irregular horizontal bends in cable trays are handled by measuring the required angle, calculating offsets, and fabricating the tray on-site while ensuring compliance with standards and cable bend radius requirements. Using calculators and proper fabrication techniques ensures safe, organized, and structurally sound cable routing .