Cable trays and plastering

Installing cable trays after plastering requires careful planning, precise support placement, and secure mounting to protect both the plaster and the cables. 1.

Plan the Route

Before touching the trays, determine the exact path for the cable trays on walls or ceilings. Use a laser level or chalk line to mark straight lines, ensuring the route avoids obstructions like pipes or HVAC ducts and maintains proper clearance from other services. Identify locations for bends, tees, or risers.

2.

Select Tray Type and Size

Choose the appropriate tray type—ladder, perforated, or solid-bottom—based on cable type, load, and airflow requirements. Calculate the tray width and depth according to the number of cables and spacing guidelines to prevent overcrowding or overheating. 3.

Mark Support Points

After plastering, mark the support points on the wall or ceiling at standard intervals (typically 1. 5–3 meters depending on tray type and load). Ensure the marks align with the previously drawn route and consider the plaster thickness to avoid cracking.

4.

Install Supports

Wall Mounting (Cantilever Brackets): Drill holes at marked points, insert anchors suitable for plastered walls (e.g., expansion bolts or toggle anchors), and attach cantilever brackets. Ensure they are level and secure. Ceiling Mounting (Trapeze Hangers): Drill into the structural ceiling, install drop-in anchors, and attach threaded rods with a horizontal strut or Unistrut channel to support the tray.

5.

Cut and Deburr Trays

Measure tray sections to fit the route, including bends or corners. Cut trays using a hacksaw or angle grinder and deburr edges to prevent damage to cable insulation. 6.

Place and Secure Trays

Lift tray sections onto the supports and fasten them using hold-down clips, bolts, or splice plates. Ensure trays are straight and level before fully tightening to avoid misalignment. Small adjustments are allowed during alignment.

7.

Lay and Organize Cables

Once trays are installed, lay cables neatly, separating by voltage or function. Use cable ties or straps to secure them, leaving slack for expansion or future adjustments. Avoid over-tightening ties to prevent cable damage.

8.

Final Checks

Verify all supports are secure and level. Ensure tray sections are properly joined and aligned. Confirm compliance with local electrical codes, including fill ratios and grounding requirements.

Following these steps ensures a safe, durable, and aesthetically clean cable tray installation after plastering, minimizing the risk of damage to both the plaster and the electrical system.