Vertical cable tray openings

Vertical cable tray openings are specially designed passages through walls, floors, or shafts that allow safe, organized, and fire-protected routing of electrical and communication cables.

Design and Material Considerations

Vertical cable trays must be constructed from materials that provide mechanical strength and corrosion resistance, such as cold-rolled steel, galvanized steel, or aluminum alloy, with surface treatments like hot-dip galvanizing or electrostatic spraying to meet anti-corrosion standards ( ). The tray system typically includes the tray, cover, and connectors, with a load-bearing capacity of at least 200 kg/m and fire resistance meeting Class B1 standards ( ).

When planning vertical openings, tray paths should avoid conflicts with ventilation ducts, water pipes, and other building services, maintaining a minimum clearance of 300 mm. For multiple layers, power and weak-current trays should be separated by at least 150 mm, and isolation plates are required at crossings ( ).

Firestopping and Safety

Openings for vertical cable trays must be properly firestopped to prevent the spread of fire through walls or slabs. This involves reserving openings, installing fire-resistant backing plates for large gaps, and sealing with firestop materials such as fire-rated boards, firestop packs, mastic, or mineral wool. Gaps between firestop packs and cables should not exceed 1 cm², and packing thickness should be at least 24 cm. Cover plates should be square, consistent, and painted evenly to close the opening ( ).

Weatherproofing and Structural Integrity

Vertical penetrations must also maintain structural stability and water tightness, especially when passing through building envelopes. Weatherproofing systems, such as fibre-reinforced cold-applied liquids, can accommodate complex arrays of cable trays and allow for last-minute positional adjustments without compromising waterproofing or thermal performance ( ). There are no strict restrictions on the size, shape, or position of the penetration relative to cladding, allowing flexibility in design and installation ( ).

Installation Best Practices

• Ensure support structures are installed according to specifications to bear the tray load.
• Maintain minimum bend radii for cables exiting the tray to prevent damage.
• Use ventilated or solid-bottom trays depending on heat generation and aesthetic requirements ( ).
• Plan for maintenance access and future cable additions when designing vertical openings.

By following these guidelines, vertical cable tray openings can provide safe, durable, and compliant pathways for electrical and communication systems in buildings.