Cables on cable trays should be laid systematically with proper support, spacing, and organization to ensure safety, heat dissipation, and ease of maintenance.

Planning and Preparation

Before laying cables, review the approved shop drawings to determine tray routes, lengths, and locations, ensuring horizontal and vertical runs only . Verify that all materials, including trays, ladders, and accessories, are in good condition and comply with project specifications . Ensure the electrical well is clean and free of obstructions, and mark tray routes while coordinating with other services to avoid clashes .

Cable Tray Selection and Support

Choose the appropriate tray type based on cable type and environmental conditions. Ladder trays are ideal for power cables due to ventilation and support points, while ventilated troughs suit smaller control or instrumentation cables . Supports should be installed at regular intervals (typically 1.2 meters) to prevent sagging, with additional support at bends, branches, and offsets . Use threaded rods, metal plugs, and slotted channels or L-angles for secure mounting .

Laying Cables

• Organized Placement: Lay cables in an orderly manner, avoiding excessive bending to prevent insulation damage .
• Spacing: Maintain proper separation between cables to reduce heat buildup and allow for future maintenance. For multicore cables, surfaces should be separated by at least 50–75 mm depending on size and grouping .
• Cable Fill: Do not exceed 40% of tray capacity to ensure adequate ventilation and prevent overheating .
• Identification: Use markers for cable identification at regular intervals to facilitate maintenance .

Securing and Bonding

Fix cables at regular intervals using cable ties or clamps, ensuring they are not overly tight to avoid crushing insulation . Ensure all trays and cables are properly bonded and grounded to comply with electrical safety standards .

Special Considerations

• Fire-rated walls or floors: Use fire-stopping measures to prevent fire spread through cable routes .
• Thermal insulation: Avoid direct contact with thermally insulating surfaces unless specified, as it may affect heat dissipation .
• Enclosed trenches or ducts: Maintain minimum dimensions and spacing to allow airflow and prevent overheating . By following these methods, cables in electrical wells will be safe, organized, and maintainable, reducing the risk of damage, overheating, and system failure .