Cable trays are installed under the air ducts

Cable trays can be installed under air ducts if properly supported and using code-compliant cables, but they must never be placed inside the duct itself.Key Considerations1. Cable Tray Placement: Cable trays should be installed under or alongside air ducts, not inside them, to avoid obstructing airflow, creating fire hazards, or violating building codes . Both cable trays and air ducts can share the same structural supports, such as primary steel beams or suspended concrete slabs, provided the supports are engineered for the combined load . 2. Cable Types for Plenum or Air Spaces: If the tray is located in a plenum or environmental air space, only Type MI (Mineral Insulated) or Type MC (Metal Clad) cables with impervious metal sheaths are permitted . These cables are designed to meet fire safety requirements and can be safely supported by cable trays in air-handling spaces. 3. Tray Types and Materials:Ladder trays are ideal for power cables and large conductors, offering ventilation and convenient tie points .Ventilated troughs provide continuous support for smaller control or instrumentation cables.Materials include galvanized steel, aluminum, or fiberglass-reinforced plastic (FRP) for corrosive or high-moisture environments .Trays should comply with standards such as EN 50085 or UL94 V-0 for fire resistance and durability . 4. Installation Practices:Maintain proper bending radius and segregation of cables to prevent overheating and interference .Ensure structural support spans are adequate for the tray type and cable load .Perform regular inspections to check for cable wear, tray integrity, and secure fastening .Avoid running cables inside ducts unless specifically rated for that purpose, such as inline fan cabling . 5. Coordination with HVAC Systems: Engage both electrical and mechanical engineers to ensure that cable trays do not interfere with ductwork, airflow, or maintenance access . Proper planning ensures compliance with building codes and safe, efficient operation of both electrical and HVAC systems. By following these guidelines, cable trays can be safely installed under air ducts, providing organized, accessible, and code-compliant cable management while maintaining HVAC performance and fire safety.