Installation method diagram for cable trays and trunking

Cable trays and trunking are installed using a structured sequence of marking, supporting, aligning, and securing, following approved shop drawings and manufacturer guidelines.

Preparation and Material Handling

Before installation, all materials including cable trays, trunking, ladders, and accessories should be inspected for damage, corrosion, and compliance with approved submittals. Materials must be stored in a dry, covered area and kept free of dust, oil, or scale. Ensure the work area is safe and accessible, and that all required tools and supports are available on site.

Layout and Marking

Mark the routing paths for cable trays and trunking according to approved shop drawings and coordination with other utilities. Ensure sufficient clearance from ceilings, walls, and other services. Horizontal runs should avoid interference with vertical services, and vertical risers should be clearly identified.

For trunking, mark the wall or ceiling points for fixing screws and supports before drilling.

Support and Fixing

Use G

I threaded rods (10mm for trays below 300mm, 12mm for above 300mm) and slotted C channels to support trays and trunking. Support spacing should follow manufacturer recommendations, typically ensuring deflection does not exceed 5mm mid-span when fully loaded. Additional supports are required at direction changes, bends, tees, and cable drop points.

Use dome-headed bolts, nuts, and washers with appropriate finishes to secure connections. Earth continuity conductors should be installed across gaps to maintain electrical continuity.

Installation Sequence

Install supports (threaded rods and C channels) at marked locations. Fix cable trays or trunking onto the supports, ensuring alignment and level. Install bends, tees, and junctions as per the layout, completing each run before laying cables.

Maintain minimum spacing between trays and structural elements (e.g., 40mm from ceiling),. Cut edges and fittings should be treated to prevent corrosion and sharp edges. Install covers after cable installation is complete, especially for non-perforated trays in plenum areas.

Safety and Quality Control

Follow manufacturer's health and safety guidelines for handling materials. QA/QC inspectors should verify approved procedures, shop drawings, and material compliance before and during installation. Ensure fire stopping is applied when trays or trunking pass through fire-rated elements.

Cable ties and circuit marking should be applied to maintain organization and identification.

Notes

Cable trays should allow a 25% reserve margin for future cable additions. Trunking systems may be used in special locations where conduit installation is difficult, with separate runs for power and communication cables. All horizontal and vertical runs should allow easy access for maintenance and cable installation.

This method ensures a safe, compliant, and durable installation of cable trays and trunking systems for electrical and MEP services.