Laying out cable tray bends

Cable tray bends should be laid out by marking the route, maintaining minimum bend radius, supporting the tray adequately, and cutting or joining sections precisely to ensure safe and efficient cable management.

Planning and Marking the Route

Begin by reviewing the approved shop drawings to determine the exact path of the cable tray, including horizontal and vertical runs, bends, branches, and offsets. Mark the tray route on-site, ensuring sufficient clearance for cable pulling and future maintenance. Coordinate with other services to avoid clashes and maintain proper alignment .

Maintaining Minimum Bend Radius

When designing bends, always respect the minimum bend radius of the cables to prevent damage. This radius depends on the cable type and manufacturer specifications. For most power and control cables, the bend radius is typically 6 to 10 times the cable diameter. Use pre-fabricated elbows or segmented bends to achieve smooth curves without exceeding the bend limit .

Supporting the Tray

Install supports at regular intervals, typically no more than 1.2 meters apart, and provide additional support at bends, branches, and offsets to prevent sagging. Use threaded rods, metal plugs, and slotted channels or 'L' angles to secure the tray. Ensure that the support system can handle the weight of the tray, cables, and any future additions .

Cutting and Joining Sections

Cut cable tray sections to the required length using appropriate tools, ensuring clean edges to avoid sharp points that could damage cable insulation. Use proper connectors, such as splice plates or mushroom head screws, to join sections securely. For bends, use pre-formed elbows or fabricate bends carefully, maintaining the correct angle and radius .

Additional Considerations

• For vertical bends, ensure smooth transitions to avoid cable stress.
• For horizontal offsets, use two 45° bends instead of a single 90° bend to reduce stress on cables.
• Ventilated trays are preferred for heat dissipation, while solid-bottom trays may be used where aesthetics or protection from dust is important .
• Inspect all materials before installation and remove any damaged components . By following these steps, cable tray bends can be installed safely, maintain cable integrity, and comply with industry standards such as BS EN 61537 for cable tray systems .