Cable tray bends at the joint

Cable tray bends at joints occur due to directional changes, thermal expansion, or improper support, and can be managed using appropriate fittings, expansion joints, and installation techniques.

Causes of Bending at Joints

Cable trays can bend or deform at joints for several reasons:

• Thermal Expansion and Contraction: Metal trays expand in heat and contract in cold. Without proper expansion gaps or guides, trays can bend, “snake,” or elongate bolt holes at splice plates, especially in outdoor or rooftop installations where temperature extremes occur . Aluminum expands more than steel, so longer runs require more expansion allowances .
• Improper Support: If trays are clamped too tightly or supports are spaced incorrectly, the tray cannot move freely, leading to bending at joints .
• Excessive Load or Misalignment: Heavy cable loads or misaligned joints can stress the tray, causing deformation at bends or connection points .

Types of Bends

Cable tray bends are designed to navigate obstacles and change direction smoothly:

• Horizontal Bends: Change the tray direction along a horizontal plane, typically 30–90 degrees, used to route around walls or structures .
• Vertical Inside/Outside Bends: Allow the tray to move up or down between levels, useful for transitioning from floor to ceiling or between elevations .
• Custom Bends: Can be fabricated to fit tight spaces or complex layouts, minimizing the need for additional joints .

Managing Bends at Joints

To prevent bending and maintain system integrity:

• Use Cable Tray Fittings: Elbows, bends, tees, and risers help guide cables smoothly and reduce stress at joints .
• Install Expansion Joints and Guides: Flexible couplers and expansion guides allow trays to move with temperature changes without distortion .
• Proper Support Placement: Position supports within 2 feet of expansion joints and anchor trays at midpoint supports while allowing sliding at other points .
• Material Selection: Choose aluminum for lightweight, portable installations with frequent temperature changes, or steel for heavier, more stable runs with fewer expansion requirements .

Accessories and Reinforcements

• Reinforcement at Bend Points: Strengthen sharp bends to maintain structural integrity .
• Covers and Cable Cleats: Protect cables and prevent movement inside the tray .
• Reducers and Offsets: Ensure smooth transitions between different tray sizes or widths . By combining proper fittings, expansion provisions, and careful support placement, cable tray bends at joints can be effectively managed, ensuring safe, durable, and efficient cable routing.