Cable trays are one of the most important fire-risk areas in industrial and commercial facilities. They often carry large quantities of power cables, control cables and communication cables across long distances. Once overheating, electrical faults or cable insulation failure occur, fire can spread along the cable route quickly and may affect critical equipment, production areas and building safety systems.
For this type of risk, traditional point-type detectors may not provide enough coverage. A point heat detector only monitors the area around its installation point. A smoke detector may be affected by airflow, dust, humidity or installation height. In cable tray applications, the fire risk is distributed along a route, not concentrated at one single point.
This is why UL Listed Linear Heat Detection is a practical and reliable solution for cable tray fire protection.
ANWETECH Digital Linear Heat Detector is designed to provide continuous heat detection along the protected cable route. It uses linear heat sensing cable, an adapter interface module and an end-of-line unit to create a complete fire detection system for cable trays, power distribution areas and industrial electrical installations.
Cable trays are commonly installed in power plants, industrial factories, tunnels, substations, data centers, petrochemical facilities and large commercial buildings. In many of these locations, the cable tray may be installed at height, inside a narrow corridor, under a floor, above equipment or in an area that is difficult to access for daily inspection.
The main fire risks in cable tray areas include:
In these applications, the detector should be installed close to the actual risk source. Linear heat detection cable can be routed along the cable tray, following the same path as the protected cables. This allows the system to monitor heat rise directly along the entire route.
Instead of protecting only one point, the cable becomes a continuous heat sensor.
ANWETECH Digital Linear Heat Detector works on a fixed-temperature detection principle. The sensing cable contains two conductors separated by a heat-sensitive NTC polymer material. Under normal conditions, the two conductors remain separated and the system stays in standby status.
When any section of the sensing cable is exposed to its rated alarm temperature, the internal material changes state and creates a short circuit between the two conductors. This change is monitored by the adapter unit. The adapter module then sends a confirmed alarm signal to the Fire Alarm Control Panel through a 24 VDC interface.
This means that if overheating occurs at any point along the cable tray, the linear heat cable can detect the temperature rise and trigger a fire alarm.
The system provides uniform sensitivity along the full length of the cable. It does not require field calibration or temperature adjustment, which makes it suitable for engineering projects where simple installation and stable operation are important.
A complete ANWETECH Linear Heat Detection system includes three main parts.
The linear heat cable is the main sensing element. It is installed along the cable tray or protected route. When the cable reaches its rated alarm temperature, it changes state and triggers the alarm through the adapter unit.
The product range includes multiple alarm temperature options, such as 68°C, 88°C, 105°C, 138°C and 180°C. This allows engineers to select the correct temperature rating according to the normal ambient temperature of the cable tray environment.
The adapter unit, model AT-LHMI, monitors the sensing cable and converts the cable status into a fire alarm signal. It operates on 24 VDC, with a working voltage range of 16–28 VDC. The module supports alarm and fault monitoring and is designed for integration with fire alarm control panels or passive input modules.
Key data of the adapter unit includes:
For cable tray projects, this module provides a convenient way to connect the linear heat detection cable to the fire alarm system.
The end-of-line unit, model AT-LHME, is a passive device and does not require power supply. It provides end-of-line termination for the detection loop. For EP type cable, it also provides a grounding point.
This component is important for loop supervision and stable system operation.
Temperature selection is one of the most important steps in linear heat detection design. The alarm temperature should not be selected only based on the lowest possible value. It must be selected according to the maximum normal ambient temperature around the cable tray.
ANWETECH provides several fixed alarm temperature options:
| Alarm Temperature | Maximum Ambient Temperature | Typical Cable Tray Application |
|---|---|---|
| 68°C | +45°C | Ordinary indoor cable trays and low-temperature risk areas |
| 88°C | +60°C | Industrial cable trays and general equipment areas |
| 105°C | +75°C | Higher-temperature electrical or mechanical areas |
| 138°C | +93°C | High-temperature industrial environments |
| 180°C | +121°C | Very high-temperature areas where false alarms must be avoided |
For example, if the cable tray is installed in an ordinary indoor electrical room, 68°C may be suitable. If the cable tray is installed in a hot industrial area where the normal temperature may rise significantly, 88°C or 105°C may be more appropriate.
The correct selection helps avoid nuisance alarms while maintaining effective fire detection performance.
Cable trays may be installed in different environments. Some are indoors, some are outdoors, and some are located in hazardous or corrosive industrial areas. ANWETECH provides different cable construction types to match these conditions.
The standard type is suitable for general industrial environments. It is designed for reliable performance in ordinary cable tray applications, such as indoor electrical rooms, factory cable routes, switchgear rooms and protected cable corridors.
Its construction includes galvanized steel conductors, insulation layer, polycarbonate bandage and PVC outer jacket.
The CR/OD type is designed for outdoor and harsh environments. It provides resistance to ultraviolet radiation, severe weather, acids, alkalis and salt-spray corrosion.
This type is suitable for outdoor cable trays, coastal industrial facilities, chemical plants, petrochemical areas and other locations where environmental resistance is required.
Its construction includes galvanized steel conductors, insulation layer, polycarbonate bandage and fluoropolymer outer jacket.
The EP type is designed for hazardous areas and locations with significant electromagnetic interference. It includes stainless-steel braid for EMI shielding and static-charge dissipation. The braid must be properly grounded, and suitable safety barriers are required in potentially explosive atmospheres.
This type is suitable for cable trays in oil and gas facilities, petrochemical plants, hazardous storage areas, mining sites and other classified industrial environments.
ANWETECH Linear Heat Detection provides several advantages for cable tray fire protection.
The sensing cable monitors the entire protected route. This is especially valuable for long cable trays, where point detectors may leave unprotected gaps between devices.
The cable can be installed close to the power cables or along the cable tray structure. This allows heat to be detected near the source of overheating.
Cable trays are often installed in dusty, humid, high-airflow or hard-to-reach areas. Linear heat detection is suitable for these industrial environments because it detects heat directly and does not rely on smoke movement.
With the AT-LHMI adapter unit, the system can be connected to fire alarm control panels or input modules using a 24 VDC interface. This makes it suitable for both conventional and addressable fire alarm system designs.
The fixed-temperature sensing cable does not require field calibration or temperature adjustment. This helps reduce maintenance work, especially in cable tray areas that are difficult to access.
The product range provides 68°C, 88°C, 105°C, 138°C and 180°C alarm temperature options, allowing engineers to select the right cable according to the project environment.
ANWETECH UL Listed Linear Heat Detection Cable can be used for cable tray fire protection in many industrial and infrastructure projects, including:
In power industry applications, it can be used along cable trays, transformer compartments, switchgear areas, cooling towers and solar facilities. In industrial infrastructure, it is suitable for long cable runs and areas where fire hazards may extend along a line.
When designing linear heat detection for cable tray fire protection, engineers should confirm the following points:
Correct engineering selection ensures stable detection, reliable alarm output and reduced false alarm risk.
