How to calculate the dimensions of parallel elbows for cable trays

Parallel elbows for cable trays are fabricated based on the tray's width, height, and bend radius, following standard tray dimensions to ensure compatibility and proper cable management.

Standard Dimensions

When fabricating parallel elbows, the key dimensions are derived from the straight cable tray sections:

• Width (W): Typically ranges from 50 mm to 600 mm for standard trays, depending on cable capacity and application .
• Height/Depth (H): Common heights are 50 mm, 70 mm, 100 mm, and 120 mm, which determine vertical stacking capacity and NEC fill compliance .
• Material Thickness: Steel trays often use 1.2 mm to 2.0 mm thickness, while aluminum or stainless steel may vary based on strength and corrosion resistance .
• Bend Radius: The elbow's bend radius should accommodate the minimum bend radius of the cables, typically 1.5 to 2 times the tray width for power and control cables .

Fabrication Considerations

• Elbow Type: Parallel elbows are usually horizontal or vertical, inside or outside, depending on the routing path. Ensure the elbow maintains the same width and height as the connecting tray sections .
• Material Selection: Choose materials compatible with the environment—galvanized steel, stainless steel, or aluminum—to prevent corrosion and maintain structural integrity .
• Compatibility: Fittings must match the straight tray sections in width, height, and side rail thickness to allow seamless installation and maintain load capacity .
• Modular Design: Fabricate elbows with flanges or bolt holes aligned with standard tray sections for easy assembly and grounding continuity .

Practical Tips

• Maintain a smooth internal surface to prevent cable damage during installation.
• Ensure the elbow's bend radius does not force cables to exceed their minimum bend radius, which could compromise performance.
• For multiple parallel runs, fabricate elbows with sufficient spacing to avoid cable overcrowding and allow heat dissipation. By adhering to these dimensions and fabrication guidelines, parallel elbows will integrate seamlessly with standard cable tray systems, ensuring compliance, structural stability, and safe cable management .