How to route cable trays on a construction site

Routing cable trays on a construction site requires careful planning, proper tray selection, correct support installation, and coordination with other services to ensure safety, efficiency, and compliance.

Planning the Route

Before installation, review the approved shop drawings to determine the tray layout, dimensions, installation height, and the number of layers required ( ). Mark the route on-site, considering clearances, load capacity, and separation from other services such as HVAC ducts, fire protection pipes, and drainage systems ( ). Use a laser level to ensure straight alignment and avoid sagging or misalignment ( ).

Selecting the Right Tray Type

Choose the appropriate tray type based on cable type, load, and environmental conditions ( ):

• Ladder trays: Ideal for power cables; provide ventilation and easy cable entry.
• Ventilated trough trays: Suitable for control and instrumentation cables; prevent sagging.
• Solid-bottom trays: Used for sensitive or structured cabling systems.
• FRP trays: Recommended in corrosive or high-moisture environments.

Sizing and Load Considerations

Calculate the tray width and depth based on the number and type of cables to prevent overheating or overcrowding ( ). Determine the total cable weight per meter to select the correct tray thickness and support brackets ( ).

Support and Mounting

Install supports at proper intervals, typically 1.5 to 3 meters apart, depending on tray type and load ( ). Supports can be:

• Wall-mounted cantilever arms for side support.
• Ceiling-mounted trapeze hangers for overhead routing. Use appropriate fasteners for the building structure, such as metal anchors for concrete or steel clamps for steel structures ( ).

Installation Procedure

1. Verify materials: Inspect trays, ladders, and fittings for damage and compliance with approved submittals ( ).
2. Install supports: Secure brackets and hangers along the marked route.
3. Lay trays: Connect trays using splice plates, ensuring alignment and level installation ( ).
4. Maintain vertical separation: For multi-layer installations, keep at least 30 cm between layers to avoid interference between electrical and telecommunication systems ( ).
5. Cable pulling: Use rollers or guides to prevent kinks and physical damage during cable installation ( ).

Coordination and Safety

Check for clashes with other services and hold coordination meetings with engineers if conflicts arise ( ). Ensure all bonding and grounding requirements are met, and follow local electrical codes and standards ( ). By following these steps, cable trays can be routed efficiently, safely, and in a manner that allows for future maintenance and upgrades.