Spacing of fire pipe cable tray supports

Fire-rated cable trays must be supported at intervals that prevent mechanical strain and ensure fire integrity, typically using fire-resistant materials in accordance with BS 7671 and related guidance. Support Spacing GuidelinesFire-resistant cables installed in cable trays or on supports must be supported at intervals that prevent undue mechanical strain and avoid damage from their own weight.

According to B

S 7671, wiring systems shall be supported such that they are not liable to premature collapse in the event of a fire (Clause 521. 10. 202) and all supports must be made of fire-resistant materials.

Non-metallic clips or ties alone are not sufficient for exposed installations; metal or fire-rated supports are required to maintain integrity during a fire. The spacing of supports depends on cable type, diameter, and installation method.

While B

S 7671 does not provide exact distances, guidance from the IET Selection and Erection Guidance Notes suggests that larger or heavier cables require closer support intervals, and all cables should be clipped or strapped to prevent sagging. For cable trays, typical support intervals are: Horizontal cable trays: Supports every 1. 5–3 meters depending on tray load and cable weight.

Vertical runs: Supports every 1–2 meters, ensuring cables do not pull on terminations. Short or light cables: May allow slightly longer intervals if mechanical strain is minimal.

Fire Safety Considerations

All supports must withstand fire conditions to prevent collapse of the cable system. Maintain adequate separation from other services, such as fire pipes or ducts, to prevent heat transfer or interference. A minimum 200 mm separation is recommended where possible.

Cable trays should be installed according to BS EN 61537 for ladder and tray systems, ensuring compatibility of components and safe load distribution.

Installation and Maintenance

Conduct design reviews to ensure support spacing meets mechanical and fire safety requirements. Follow the approved layout strictly during construction to maintain proper support intervals. Perform routine inspections to check for sagging, loose supports, or damage, and replace any non-compliant supports immediately.

Train personnel on the importance of fire-rated support materials and correct installation practices. By adhering to these guidelines, fire-rated cable systems will maintain structural integrity, reduce mechanical strain, and comply with fire safety regulations.