Specifications of fire cable trays

Fire cable trays are designed to maintain electrical circuit integrity under fire conditions, with specifications covering fire resistance, materials, load capacity, and installation standards.

Fire Resistance Ratings

Fire cable trays are typically specified with EI ratings, which indicate the duration a tray maintains integrity and insulation during a fire. Common ratings include: EI60: Suitable for moderate-risk areas or secondary systems, providing 60 minutes of fire resistance. EI90: Standard industrial and infrastructure applications, offering 90 minutes of protection.

EI120: High-risk or critical systems, ensuring 120 minutes of fire resistance. These ratings depend on tray type, material thickness, cable loading, mounting orientation, support spacing, and protection methods such as fire wraps or intumescent coatings.

Materials and Construction

Fire cable trays are manufactured from materials selected for mechanical strength and corrosion resistance: Steel: Painted, pre-galvanized, or hot-dip galvanized for indoor and outdoor use. Aluminum: Lightweight and corrosion-resistant, suitable for industrial or offshore environments. Stainless Steel: Used in highly corrosive or hygienic environments.

FR

P (Fiber Reinforced Plastic): Non-metallic option for corrosive or high-humidity areas. Tray types include ladder, perforated, solid-bottom, and wire mesh, each providing different levels of ventilation, cable support, and EMI shielding.

Mechanical and Electrical Specifications

Load Capacity: Trays must support the total cable weight plus any additional loads, with support spacing per manufacturer recommendations. Tray Dimensions: Width and thickness are selected based on cable quantity, weight, and future expansion needs. Supports and Spans: Wall brackets, trapeze hangers, or pedestal supports are used to maintain level and minimize deflection.

Electrical Continuity: Metallic trays require proper bonding and grounding to ensure safety and compliance with electrical codes.

Installation Standards

Fire cable trays must comply with recognized standards to ensure safety and regulatory compliance: NEC / NFPA 70 (U. S.): Covers sizing, support, and separation requirements for cable trays.

IE

C 61537 (International): Specifies load ratings, material standards, and joint design.

E

N 50200 / BS 476: Fire performance standards to maintain cable integrity under fire conditions. Installation tolerances typically require horizontal deviation ≤2mm/m and vertical deviation ≤3mm/m, with trays mounted level, plumb, and securely.

Additional Considerations

Cable Segregation: Power and signal cables should be routed separately to minimize interference. Ventilation and Heat Dissipation: Proper spacing and perforations prevent overheating. Future Expansion: Trays should allow for additional cables without compromising fire resistance or mechanical integrity.

By adhering to these specifications, fire cable trays ensure circuit integrity, safety, and compliance in industrial, commercial, and critical infrastructure environments.