What cables should be installed in a fire-fighting power cable tray

Fire-fighting power cable trays should contain fire-resistant power and control cables compliant with BS8519, designed to maintain circuit integrity for 30, 60, or 120 minutes under fire conditions.

Recommended Cable Types

BS8519-compliant cables are the primary choice for fire-fighting power cable trays. These include:

• Fire-resistant power cables: Single-core or multi-core cables designed to maintain electrical supply to critical systems during fire events, ensuring operational continuity for life safety and firefighting equipment .
• Control cables: Used for auxiliary control circuits in fire-fighting systems, including sprinkler systems, smoke barriers, and evacuation lifts .
• Enhanced fire-resistant cables (PH120): Required in complex or high-rise buildings, unsprinklered structures, or where a two-hour operational period is mandated .
• Steel wire armoured (SWA) fire performance cables: Provide additional mechanical protection against impact and water jets, suitable for exposed or high-risk areas .

Fire Survival Times

Cables are classified by fire survival times to ensure circuit integrity:

• 30 minutes (PH30): Suitable for standard buildings and less critical circuits.
• 60 minutes (PH60): Standard for life safety systems in large or complex buildings.
• 120 minutes (PH120): Required for high-risk or unsprinklered buildings, ensuring firefighters can operate safely during extended fire exposure .

Installation Considerations

• Cable tray rating: Only use UL-listed or equivalent tray-rated cables to ensure compliance with mechanical, thermal, and fire performance requirements .
• Segregation: Power and control cables should be separated from non-critical circuits to prevent compromise of fire-fighting systems .
• Support and protection: Cables must be properly supported, secured, and protected from mechanical damage, including crush and impact resistance where necessary .
• Voltage drop and sizing: Fire-resistant cables have higher resistance at elevated temperatures; sizing must account for voltage drop under fire conditions to maintain system performance .

Summary

For fire-fighting power cable trays, install BS8519-compliant fire-resistant power and control cables, selecting the appropriate fire survival time (30, 60, or 120 minutes) based on building complexity and fire risk. Use steel wire armoured or enhanced cables where mechanical protection is required, ensure proper tray rating, and follow installation best practices to maintain circuit integrity during fire emergencies .