Fireproof sealing requirements for cable tray openings in computer rooms

Cable tray openings in computer rooms must be sealed with fire-resistant materials such as mineral wool, intumescent sealants, or firestop packs to restore the fire-resistance rating of walls and floors and prevent the spread of fire and smoke.

Key Requirements

1. Fire-Resistant Materials: Openings around cable trays should be sealed using fire-rated boards, firestop packs, intumescent sealants, or fire-resistant mineral wool. These materials must adhere to the fire rating of the wall or floor assembly and be compatible with the penetrant type (cables, conduits, or trunking) (AllPCB, ExpertCE, Penosil, Wolman ). 2. Installation Procedures:

• Prepare the opening: Clean the area of dust, oil, or debris to ensure proper adhesion of firestop materials (ExpertCE ).
• Packing: For large openings, install a fire-resistant backing plate before filling. Firestop packs should be placed in an orderly sequence, with gaps between packs and cables not exceeding 1 cm² and packing thickness not less than 24 cm (AllPCB ).
• Sealant Application: Apply intumescent acrylic or firestop mastic over the packed opening. Intumescent sealants expand under heat to block fire and smoke (Penosil ).
• Cover Plates: Use square, evenly painted cover plates to close the opening, ensuring a tight and reliable seal without visible cracks or voids (AllPCB ). 3. Fire Rating Compliance:
• Verify the UL-listed or EN-tested firestop system for the specific wall or floor assembly and cable type. Systems may provide EI60 to EI120 ratings, depending on the application (Wolman ).
• Ensure the sealing restores the original fire-resistance of the building element and resists external influences such as smoke, heat, and water penetration (Professional Electrician ). 4. Slab and Floor Penetrations:
• Cable trays passing through slabs should have a waterstop of at least 50 mm at floor level and 20–30 mm of firestopping at slab penetrations, with a fire-support plate installed on top (AllPCB ).
• All gaps inside and around metal trunking must be sealed completely, both internally and externally. 5. Re-penetrability and Maintenance:
• For computer rooms where cables may be added or removed, consider re-penetrable systems such as firestop pillows, sealbags, or modular panels that allow future modifications without compromising fire safety (ExpertCE, Wolman ). 6. Documentation and Inspection:
• Label penetrations with the UL system number, installer, and date, or maintain manufacturer documentation for inspection by the Authority Having Jurisdiction (ExpertCE ).
• Regular inspections ensure that seals remain intact and effective over time.

Recommended Products and Systems

• Firestop Intumescent Acrylic Graphite 682 – expands under heat to block fire and smoke (Penosil ).
• KBS® Sealbags and Mortar – flexible and permanent solutions for cable penetrations, tested to DIN 4102-9, EN 1366-3, and UL 1479 (Wolman ).
• Fire-rated PU foams – for filling irregular gaps around cables (Penosil ). By following these requirements, cable tray openings in computer rooms can maintain the integrity of fire-rated walls and floors, prevent the spread of fire and smoke, and comply with relevant safety standards.