The fireproof layer thickness for cable trays typically ranges from 60 µm for standard trays to 24 mm for firestop packing, depending on the tray type and fire protection method.

Standard Fireproof Coatings

For metal cable trays, fireproofing is often achieved using intumescent coatings or fire-resistant paints. For example, a 300 mm-wide cable tray requires a minimum fireproof layer thickness of 60 µm when using coatings such as epoxy-based intumescent systems or aluminized polypropylene scrim encapsulation . These coatings form a dense, insulating char layer under high temperatures, reducing heat transfer and protecting the cables .

Firestop Packing and Slab Penetrations

When cable trays pass through walls, slabs, or electrical shafts, additional fireproofing is required. Firestop packs are used to seal gaps around cables and trays, with a minimum packing thickness of 24 mm and a maximum gap area of 1 cm² between the pack and cables . At slab penetrations, a fire-support plate is recommended, and the firestopping layer should be 20–30 mm thick to ensure reliable sealing and prevent flame propagation .

Material Considerations

• Intumescent coatings: Expand under heat to form a protective char; thickness depends on tray width and fire rating requirements .
• Fire-resistant tapes or wraps: Typically applied in layers to achieve the required thickness, often 60–100 µm per layer .
• Mineral wool or fire-rated boards: Used in combination with firestop packs for high-risk or industrial installations .

Practical Guidelines

• Ensure uniform application of coatings or wraps to avoid weak spots.
• Maintain mechanical stability of trays; fireproof layers should not compromise load-bearing capacity .
• Follow manufacturer specifications for each fireproofing product, as thickness requirements may vary with fire rating, tray width, and environmental conditions . In summary, fireproof layer thickness varies by method and tray type: standard coatings require ≥60 µm, while firestop packing and slab penetrations require 20–30 mm or more, ensuring both fire resistance and structural integrity.