Making the most difficult bend in cable trays

The most difficult bend to construct in cable trays is typically the internal 90° bend, especially when a tight radius is required.

Why Internal 90° Bends Are Challenging

Internal 90° bends require precise cutting, flattening, and alignment to maintain the tray's structural integrity and allow smooth cable pulling . Unlike external bends, internal bends involve compressing the tray inward, which can cause deformation if not done carefully. Field fabrication often requires removing portions of the tray lip, cutting along the centerline, and using gussets to reinforce the bend . Achieving a smooth, accurate bend without damaging the tray is labor-intensive and demands skill.

Factors Affecting Bend Difficulty

• Bend Radius: Tighter radii increase difficulty because the tray material is more prone to cracking or warping . Manufacturers often provide bends in various radii (e.g., 12”, 24”, 36”, 48”) to accommodate installation needs .
• Tray Material and Size: Steel trays are harder to bend than aluminum, and wider trays require more force and careful handling .
• Tools and Techniques: Manual bending, hydraulic, or electric benders can be used, but field bends without specialized machines are more challenging . Techniques like three-point bending or using a crimping bar are common for tight bends .
• Code Compliance: Ensuring the bend meets NEC and manufacturer guidelines for minimum radius and cable fill adds complexity .

Other Challenging Bends

• Offset Bends: These require multiple angles to navigate around obstacles and precise measurement to maintain alignment .
• Compound Bends: Combining horizontal and vertical bends in a single section increases difficulty due to the need for multi-plane adjustments .

Practical Tips

• Always measure and mark the tray accurately before bending.
• Use appropriate protective equipment when cutting or grinding tray lips.
• Reinforce bends with gussets to maintain strength and alignment.
• Consider pre-fabricated bends for extremely tight or complex angles to reduce field errors. In summary, internal 90° bends with tight radii are the most difficult to construct in cable trays due to the precision, reinforcement, and careful handling required to maintain structural integrity and ensure smooth cable installation .