Cable trays in electrical shafts

Cable tray installation in electrical shafts requires careful planning, proper material handling, secure mounting, and adherence to safety and electrical standards.Planning and PreparationBefore installation, review the approved shop drawings to determine tray routes, lengths, and locations within the electrical shaft or service corridor. Ensure the area is cleared of debris and civil works are complete. Mark horizontal and vertical runs, maintaining adequate clearance for cable pulling and future maintenance. Coordinate with other services to avoid clashes and ensure proper alignment and levels .Material Handling and StorageAll cable trays, ladders, and accessories should be inspected for damage and verified against approved material submittals. Store trays horizontally on flat surfaces with timber supports at intervals of about one meter, and cover them to protect against moisture and sunlight. Accessories should be organized by type and size to prevent loss or damage .Selecting Tray Type and SizeChoose the appropriate tray type based on cable type, load, and environment:Ladder trays: allow airflow and easy cable entry, suitable for heavy or high-voltage cables.Perforated trays: support lighter loads and provide ventilation.Solid-bottom trays: protect cables from dust or debris. Tray width and depth should be calculated based on cable count, type, and spacing to prevent overheating or wasted space .Mounting and SupportInstall supports using brackets, hangers, or clamps, spaced typically 1.5 to 3 meters apart depending on tray type and load. Ensure trays are level, straight, and securely connected using appropriate fittings. For long vertical runs in shafts, use intermediate supports to prevent sagging and maintain structural integrity .Cable Laying and OrganizationLay cables neatly within the tray, using cable ties or straps to separate by voltage or function. Maintain the minimum bend radius for cables at entry and exit points. Leave slack for thermal expansion, movement, or future modifications .Grounding and BondingMetal trays must be properly grounded and bonded to ensure electrical safety. Use bonding jumpers across tray sections to maintain continuity and comply with electrical standards .Final Checks and DocumentationInspect the installation for loose clamps, misalignment, overfilled sections, or unsupported spans. Label cables clearly and maintain updated documentation for identification, troubleshooting, and future audits. Routine maintenance should include checking for corrosion, loose wires, or damaged supports .Safety ConsiderationsOnly trained personnel should perform installation. Avoid using trays as walkways or ladders. Follow relevant standards such as BS EN 61537 for cable trays and BS 6946 for channel support systems to ensure safe and compliant installation . By following these steps, cable trays in electrical shafts can be installed safely, efficiently, and in a manner that allows for easy maintenance and future expansion.