On-site assembly of cable trays

On-site fabrication and installation of cable trays involves careful material handling, support preparation, alignment, and adherence to standards to ensure a safe and reliable electrical distribution system.

Material Inspection and Preparation

All cable trays, ladders, and accessories must be inspected upon delivery to ensure compliance with approved material submittals and project specifications. Damaged or non-conforming materials should be reported and removed from the site immediately. Trays should be stored horizontally on flat surfaces with timber supports at regular intervals and protected from moisture and direct sunlight to prevent corrosion or deformation .

Support and Layout

• Supports must be installed according to the approved shop drawings, ensuring proper spacing: typically 2 meters for perforated trays and 3 meters for ladder-type trays to avoid strain on the system .
• Trays should be self-supporting and fixed to steel structures, concrete, or standard steel shapes using high-tensile bolts, washers, and nuts.
• The layout should follow Issued for Construction (IFC) drawings, maintaining adequate space for cable installation and future maintenance .

Installation Procedure

1. Review Shop Drawings: Confirm tray routing, lengths, and locations.
2. Install Supports: Ensure stability and alignment of the tray system.
3. Assemble Trays: Connect sections using bolted mechanical connectors or bonding jumpers to maintain electrical continuity.
4. Cable Fixing: On horizontal trays, cables are grouped and secured every 2–3 meters; on vertical or edgewise trays, use stainless steel strips at 1-meter intervals .
5. Load Considerations: Design trays to carry the specified load (commonly 100 kg/m) and allow 20% extra space for future expansion .
6. Earthing and Bonding: Ensure proper grounding of all tray sections to prevent electrical hazards .

Standards and Best Practices

• Follow IEC 61537, NEMA VE1/VE2, and project-specific standards such as ARAMCO for industrial installations .
• Maintain thermal spacing to prevent overheating of high-voltage cables.
• Use galvanized or stainless steel trays in corrosive environments to enhance durability .
• Ensure trays are perforated or ladder-type to allow ventilation and prevent water retention .

Safety and Quality Checks

• Conduct inspections according to the Inspection & Test Plan (ITP) before and after installation.
• Verify alignment, support spacing, and secure connections.
• Ensure stress-free cable laying to prevent damage to insulation or conductors .

Summary

Successful on-site fabrication and installation of cable trays requires careful planning, adherence to standards, proper material handling, and precise installation techniques. Following these guidelines ensures a reliable, safe, and maintainable cable management system for industrial and commercial electrical infrastructure.