Temperature-sensitive or linear heat detection (LHD) cables should be installed centrally or above cable trays, secured with appropriate clips, and spaced to ensure full coverage for early fire detection.

Key Installation Guidelines

Positioning: For cable trays up to 0.6 meters wide, a single run of LHD cable should be installed centrally above the tray. For trays wider than 0.6 meters, two runs spaced evenly across the tray are recommended to ensure complete coverage ( ). In multi-tier trays, cables can be mounted above or below each tier using V-clips, L-clips, or beam clips, ensuring that the cable does not obstruct access to the tray ( ). Height and Clearance: LHD cables should be positioned 150–250 mm above the tray to avoid interference with power or data cables ( ). This height allows maintenance access while maintaining detection effectiveness. In some cases, cables can be installed beneath the lowest tray to detect debris or rubbish fires ( ). Securing the Cable: Use clips or fixings at intervals no greater than 1.2 meters. If cable ties are used, they should include a neoprene sleeve and not be over-tightened to prevent damage to the cable's outer insulation ( ). Stainless steel braided or coated cables are recommended for robustness against mechanical damage and environmental factors such as dust, moisture, and vibration ( ). Layout Considerations:

• Single runs are sufficient for narrow trays; wider trays require multiple runs ( ).
• Serpentine or wave patterns can maximize coverage in long or irregular trays ( ).
• Zones can be defined for alarm and extinguishing purposes, and local fire regulations should be followed ( ).
• Test switches or sample ovens can be used for periodic maintenance without replacing the cable ( ). Integration and Monitoring: Temperature-sensitive cables can be connected to conventional fire panels, addressable switch monitor units, or PLCs. Advanced systems, such as Digital Location Interfaces, allow monitoring of long cable runs and provide precise alarm locations ( ). Some systems also monitor the rate-of-temperature-change and can detect hot spots, enhancing early warning capabilities ( ). Environmental Protection: Cables should be chosen for resistance to dust, dirt, moisture, and temperature fluctuations. Protective sleeves or coatings are recommended to prevent abrasion from tight fastenings or environmental exposure ( ).

Summary

Proper installation of temperature-sensitive cables in cable trays involves central or above-tray placement, secure mounting with appropriate clips, correct spacing, and environmental protection. Multi-tier trays require careful planning to ensure full coverage, and integration with monitoring systems enhances early detection of overheating or fire hazards. Regular testing and adherence to local fire codes are essential for maintaining system reliability.