Steps for sealing cable trays

Sealing cable trays involves using weatherproofing systems, cable entry seals, and enclosures to protect cables from water, dust, and environmental hazards while maintaining accessibility for future expansion.

Weatherproofing Cable Trays

For vertical wall penetrations, a weatherstop sealing system is commonly used. This may appear as ductwork or boxes attached to the building exterior, creating a sealed entrance for cables. Alternatively, GRP (glass-reinforced plastic) weathering systems can be applied as a cold-applied liquid to seal the tray directly against the wall, providing a waterproof and windproof barrier without additional ductwork.

For roof penetrations, service risers or upstands are used to create a structurally sound, waterproof seal. These can be combined with GRP sealants to ensure the tray remains protected from rain and wind while maintaining durability.

Cable Entry Seals

To seal individual cables or multiple cables exiting a tray, cable entry seals are highly effective. These include: Grommet seals: Flexible rubber-like seals that fit around individual cables, protecting them from wear and environmental exposure. Compression seals: Mechanically tightened seals that create a water-tight fit, ideal for industrial or high-moisture environments.

Multi-cable entry seals: Allow multiple cables to pass through a single opening while maintaining a tight seal around each cable. Systems like Roxtec entry seals use removable layers to adapt to different cable sizes and allow for future expansion without additional openings.

Enclosures and Tray Modifications

For additional protection, enclosing the cable tray or constructing a small “doghouse” around the tray can prevent water ingress and dust accumulation. This is particularly useful for roof penetrations or areas exposed to heavy weather. A gooseneck or raised entry may be used to direct water away from the penetration point.

Practical Tips

Ensure the sealant or enclosure is compatible with the building materials and cladding. Maintain accessibility for future cable additions by using modular or expandable sealing systems. Consider fire safety and structural integrity when selecting sealing methods.

For high-density cable installations, multi-cable entry seals can replace multiple individual glands, saving space and installation time. By combining weatherproofing systems, cable entry seals, and protective enclosures, cable trays can be effectively sealed against environmental hazards while remaining flexible for maintenance and expansion.