Cable trays are considered concealed works

Cables can be considered concealed works when installed within walls, ceilings, or floors, but cable trays are generally not classified as concealed because they are open support structures, even if positioned above ceilings or behind partitions.

Concealed Cables

Concealed cables are those installed in such a way that they are hidden from view, typically within walls, floors, or ceilings. According to BS 7671, concealed wiring must be installed to minimize mechanical damage from impact, abrasion, penetration, tension, or compression during installation, use, or maintenance . For example, PVC-insulated cables in domestic installations must be positioned at least 50 mm from surfaces to avoid accidental penetration by nails or screws . Concealed cables may also require adherence to prescribed “safe zones” within walls or partitions to ensure protection .

Cable Trays

Cable trays, on the other hand, are open or partially open support structures designed to route and support electrical cables . They are typically installed above ceilings, along walls, or in industrial spaces to provide organized pathways for power and data cables. While cable trays may be positioned out of direct sight, they are not fully enclosed within the building structure and remain accessible for inspection, maintenance, and future cable additions . Their open design allows for ventilation and easy access, which differentiates them from truly concealed wiring.

Key Distinction

• Concealed works: Cables fully hidden within structural elements (walls, floors, ceilings) and not readily accessible without removing part of the structure .
• Non-concealed works: Cable trays and other containment systems that are visible or accessible, even if located above ceilings or behind panels . In practice, while cables within a tray may be partially hidden, the tray itself is considered part of the exposed containment system, not a concealed installation. Compliance with BS 7671 still applies to cables in trays, including spacing, load, and protection considerations . Conclusion: Cables installed inside walls, floors, or ceilings are classified as concealed works, whereas cable trays, due to their open and accessible nature, are generally not considered concealed works, even if they are positioned out of direct view.