Should cables be run through cable trays or walls

Cables do not always require cable trays when passing through walls; proper firestopping and conduit or raceway protection are typically sufficient.

Cable Tray Purpose and Limitations

Cable trays are designed to support and route multiple cables in open, accessible areas, providing ventilation, organization, and physical protection for power and data cables. They are generally not intended to be enclosed within walls or partitions, as NEC Article 392 specifies that trays must remain accessible for maintenance and inspection. Using a cable tray inside a wall would prevent proper access and could violate code requirements.

Wall Penetrations and Fire Safety

When cables pass through walls, floors, or slabs, the primary concern is firestopping rather than tray support. Openings must be sealed with fire-resistant materials such as firestop packs, mineral wool, or fire-rated mastic to prevent the spread of fire. For large openings, a fire-resistant backing plate may be installed before sealing.

All gaps around cables or metal trunking should be tightly sealed, and cover plates should be used to close the opening.

Alternatives to Cable Trays in Walls

Instead of trays, cables passing through walls are typically routed through: Conduits or raceways: Metal or nonmetallic conduits provide mechanical protection and maintain code compliance. Fire-rated sleeves: These allow cables to pass through walls while maintaining fire-resistance ratings. Direct penetration with firestopping: For small bundles, cables can pass directly through a wall opening if properly sealed with firestop materials.

Summary

While cable trays are essential for open, horizontal, or vertical cable runs in industrial or commercial spaces, they are not required or recommended for wall penetrations. The key requirements for cables passing through walls are mechanical protection, firestopping, and compliance with NEC and local building codes. Properly installed conduits or firestopped openings provide the necessary safety and code compliance without the need for a cable tray.