Cable Tray Fires: Protection with Direct Low Pressure (DLP) Fire Suppression Systems
Cable trays are an essential part of electrical distribution in industrial plants, data centers, utilities, and manufacturing environments. They concentrate power and communication cables in overhead or underfloor routes, allowing organized and accessible cable management. But this same concentration of wiring also creates a fire risk that can be difficult to detect and control.
A localized ignition inside a cable tray can move rapidly if insulation breaks down or if cables are closely packed. Traditional room-level suppression systems do not detect these fires early enough, which is why targeted suppression inside the tray is increasingly recommended.
Why Cable Tray Fires Are a Significant Risk
Cable trays present several fire hazards due to their construction and operating conditions. Common risk factors include:
High Cable Density
The more cables in a tray, the more heat they generate and retain.
Aging or Damaged Insulation
As insulation deteriorates, the likelihood of electrical faults and arcing increases.
Overloaded Conductors
Overheating from excessive current can ignite combustible insulation.
Restricted Airflow
Especially in enclosed or covered trays, heat buildup accelerates ignition.
These conditions allow fires to begin inside the tray long before smoke is visible in the surrounding area.
How Quickly Cable Tray Fires Spread
Research shows that cable jackets can ignite between 150–300°C, depending on material and load. Once insulation softens, heat can transfer rapidly to adjacent cables, creating a chain reaction.
Because cable trays run horizontally across rooms or vertically up equipment rows, a fire can travel the full length of the tray if not suppressed early. This can lead to:
- Damage to power circuits
- Shutdown of critical equipment
- Loss of communication pathways
- Facility-wide downtime
Stopping the fire inside the tray is the most effective way to prevent broader system impacts.
Why DLP Systems Are Effective for Cable Tray Protection
Direct Low Pressure (DLP) clean agent systems offer a practical solution for detecting and suppressing fires inside cable trays.
Point-of-Origin Detection
A heat-sensitive detection tube runs along the tray. When exposed to a fire’s heat, the tube ruptures at the ignition point, triggering immediate discharge.
Localized Clean Agent Discharge
The clean agent is released directly where the tube opens, suppressing the fire before it spreads along the tray.
Autonomous Operation
DLP systems require no wiring, sensors, or power, making them effective even when electrical systems fail.
Flexible for Overhead or Underfloor Trays
Tubing can be routed along open, enclosed, vertical, or horizontal cable trays with minimal installation work.
These features make DLP an ideal fit for tray-level fire protection.
Installing DLP Systems on Cable Trays
A typical installation involves:
- Routing the tube along the length of the tray
- Positioning it near high-risk cable bundles
- Securing the cylinder near an accessible location
- Ensuring routing avoids sharp edges and bends
- Testing system pressure after installation
Because the system is mechanical, installation time is low and no integration with electrical systems is required.
When to Consider DLP Protection for Cable Trays
DLP suppression is recommended for cable trays when:
- Power or communication continuity is critical
- Trays carry high-density cabling
- Equipment downtime is expensive
- Trays run across multiple equipment zones
- The facility uses combustible cable jackets
- A fire in a tray could interrupt production or utilities
DLP adds a layer of protection that prevents small thermal events from becoming facility-level incidents.
Protecting Critical Infrastructure with Orbis® DLP Systems
Cable tray fires can cause extensive operational disruption if not contained quickly. Orbis® DLP systems provide early detection and immediate suppression inside the tray, helping maintain continuity of electrical and communication systems.
