Solid-bottom metal cable trays, often with covers and dividers, are recommended for alarm cable installations to ensure signal integrity, fire safety, and compliance with standards.

Recommended Tray Type

For alarm cables, including fire alarms, intrusion detection, and access control systems, solid-bottom cable trays are preferred. These trays provide continuous support for delicate low-voltage cables, prevent sagging, and reduce mechanical stress on the cable jacket. A metal divider can be added to separate alarm cables from power cables, minimizing electromagnetic interference (EMI) and false alarms .

Material Selection

• Steel trays are most common for fire alarm systems due to their high heat resistance. Steel maintains structural integrity up to approximately 1400℃, ensuring the system remains operational during a fire for at least two hours .
• Hot-dip galvanized steel is recommended for indoor areas with potential moisture or mild corrosion, providing superior rust protection .
• Aluminum trays are suitable for outdoor or EMI-sensitive environments because they are lightweight, corrosion-resistant, and non-magnetic .

Installation Considerations

• Covers: Solid or ventilated covers protect cables from dust, debris, and accidental damage while maintaining signal reliability .
• Separation from power cables: Use dividers or separate trays to prevent electrical noise from affecting alarm signals .
• Tray fill: Follow the 40% fill rule to avoid overcrowding, which can cause overheating or mechanical stress .
• Expansion joints: For long runs, include expansion joints every 30 meters to accommodate thermal expansion and prevent tray deformation .

Compliance and Safety

Ensure that the tray system and installation comply with UL 2196 or EN 1363-1 standards for fire alarm systems. Properly rated trays, bolts, and brackets are critical to maintain system functionality during emergencies .

Summary

For alarm cable installations, solid-bottom steel or aluminum trays with covers and dividers are the best choice. They provide mechanical support, fire resistance, EMI protection, and compliance with safety standards, ensuring reliable operation of alarm systems in both normal and emergency conditions .