Drilling holes at cable tray connections

Drilling holes for cable tray fixing requires precise marking, correct drill sizes, and proper support installation to ensure secure and compliant cable tray systems.

Marking and Planning

Before drilling, mark the route of the cable tray according to approved shop drawings or layout plans. Identify the positions for support system fixing points, including wall, ceiling, or floor mounts, and ensure adequate spacing to prevent stress on cables where they enter or leave the tray. Use templates or splice plates to locate hole positions accurately, especially for field-cut trays.

Drilling Procedure

Select the correct drill size based on the hardware supplied with the cable tray, such as bolts, anchors, or self-tapping screws. Clamp the splice plate or template to the tray or support channel to guide the drill. Drill through the marked points, ensuring holes are clean and free of burrs.

Remove any sharp edges to prevent cable damage. For wall or ceiling installations, drill anchor fixing holes and insert appropriate anchors or fisher plugs before fixing the tray or trunking.

Support Installation

Use threaded rods (e.g., 10mm for trays below 300mm, 12mm for above 300mm) to suspend trays from ceilings. Install slotted GI channels or brackets using nuts and washers, then mount the cable tray sections onto these supports. Ensure adequate spacing around trays for cable installation and maintenance.

Protect cut or drilled surfaces with zinc-enriched paint to prevent corrosion.

Fire Safety and Compliance

When drilling through fire-rated walls or floors, ensure that fire separation is reinstated after penetration. Follow relevant electrical codes and containment standards to maintain safety and compliance.

Final Steps

Join adjoining tray sections using splice plates or joiners. Secure cables with ties at intervals, marking circuit references where required. Verify alignment, leveling, and stability of the entire tray system before installing cables.

By following these steps, you can ensure that cable trays are securely fixed, compliant with standards, and safe for long-term cable management.