Sealing the opening of the cable tray in the low-voltage room

Openings for cable trays in low-voltage rooms should be tightly sealed using firestop materials, protective plates, and fireproof mortar to prevent fire and smoke spread.Key Steps for Sealing Cable Tray Openings1. Reserve Proper Opening Size: Ensure the opening is slightly larger than the cable tray dimensions, typically adding 100 mm to width and height, to allow for effective sealing and installation of firestop materials .2. Install Protective Steel Plates: Use 4 mm thick steel plates around the opening. Extend the plates by 200 mm beyond the tray dimensions, treat them for rust, coat with anti-rust paint, and apply a fireproof finish . This protects the tray edges and provides a stable base for fireproof materials.3. Layer Fire Blocking Materials: Place firestop packs, mineral wool, or fire-rated boards layer by layer, ensuring compact stacking. The gap between firestop packs and cables should not exceed 1 cm², and packing thickness should meet design requirements, typically not less than 24 cm .4. Fill Gaps with Fireproof Mortar or Caulk: Use intumescent caulk or fireproof mortar to fill all gaps between cables, trays, and protective plates. Ensure uniform, tight filling without voids or cracks . UL-listed products like 3M Fire Barrier Moldable Putty+ or IC 15WB Caulk are recommended for compliance and durability .5. Install Cover Plates: Close the opening with square, evenly painted cover plates to provide a clean finish and additional fire protection . Ensure plates are securely fixed and aligned with the surrounding wall or floor surface.6. Waterstop Platforms (if vertical shafts): For openings in vertical shafts, construct a smooth waterstop platform to support firestop materials and prevent water ingress . Align the stacked firestop materials with the platform for a compact, effective barrier.7. Inspection and Maintenance: After installation, check for visible cracks, voids, or loose materials. Proper layout and positioning should allow for future maintenance and cable additions without compromising fire safety .Recommended MaterialsFire-rated boards or mineral wool for packingFirestop packs or pillows (UL-listed)Intumescent caulks (e.g., IC 15WB Caulk)Moldable firestop putty (e.g., 3M FSP-SLP-M)Protective steel plates, treated and fireproofedBy following these steps, the cable tray openings in a low-voltage room will be effectively sealed against fire and smoke, compliant with safety standards, and maintain a professional, durable finish .