Special cables

Digital Linear Heat Detector

Protectowire Digital Linear Heat Detector is the most widely used linear heat detector in the fire detection industry. It is a continuous heat detector capable of detecting heat anywhere along its length. The sensor cable is comprised of two steel conductors individually insulated with a proprietary heat sensitive polymer. The insulated conductors are twisted together to impose a spring pressure between them, then wrapped with a protective tape and finished with a protective outer jacket.

  • Detects at any point along its length providing uniform sensitivity.
  • Available in a wide range of operating temperatures and outer jackets.
  • Provides alarm point location with suitably configured control panels.
  • Simple design for easy troubleshooting and low maintenance costs.
  • Outer jackets resist corrosion, chemicals, dust, dirt, moisture, and temperature extremes.

Features & Benefits


  • Identifies and displays, at the control panel, the alarm location anywhere along its length when used with the exclusive Protectowire Alarm Point Location Meter.
  • Sensitivity not effected by changes in ambient temperature or length of cable used on the detection circuit. Compensating adjustments are not required.
  • Simple to install and splice with common tools. Junctions can be made without affecting the integrity of the system.
  • Compatible with other types of alarm initiating devices on the same circuit such as manual pull stations, thermal heat detectors and smoke detectors.
  • Can be installed in hazardous areas when used with suitably approved Protectowire FireSystem Control Panels.
  • Full range of temperatures and models available to accommodate the most demanding applications.
  • Different temperature detectors may be utilized in the same initiating circuit.
  • Available on stainless steel messenger wire for installations where mounting is difficult such as large open areas.
  • Portable test equipment available for easy field service.
  • Ideally suited for activation of extinguishment equipment, such as deluge or pre-action sprinkler systems

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Protectowire FiberSystem 8000

The Protectowire FiberSystem 8000 is known throughout the world as one of the reliable and intelligent linear heat detection systems using state of the art fiber optic sensing technology.

The system consists of Type PFS Fiber Optic Sensor Cable and the PTS Controllers with related software. The PTS Series Controllers can be configured for various alarm criteria and can be connected to an approved fire alarm control panel using relay inputs and outputs. The system is specifically designed for high risk commercial and industrial hazards that demand high reliability and customized system features.

  • Unique zoning capabilities. A single length of sensor can contain up to 256 zones.
  • Multiple alarm initiating criteria by zone.
  • Programmable custom operating logic.
  • Capable of continuous temperature monitoring in real time.
  • Graphic display of temperature profile, fire size, and spread using computer interface.
  • LAN Interface (TCP/IP) enables remote access from multiple locations.

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Confirmed Temperature Initiation (CTI)

The Protectowire Company is proud to announce the latest innovation in Linear Heat Detection,  Confirmed Temperature Initiation or CTI.

CTI is a new Digital Linear Heat Detection technology created and patented by The Protectowire Company. This technology is an enhancement to traditional digital linear heat detection technology and enables short circuit discrimination.

CTI confirms thermal activation of the Digital Linear Heat Detector before an alarm is initiated thereby reducing the incidence of false alarms created by physical damage to the detector. Protectowire CTI Digital Linear Heat Detectors are the only digital linear heat detectors to feature Short Circuit Discrimination.

The main benefit of CTI technology is short circuit discrimination or the ability to distinguish between thermal activation of the detector and a mechanical short caused by physical damage. This feature greatly reduces the potential for false alarms. Along with this unique feature our CTI linear heat detectors also afford all the benefits of our standard Digital Linear Heat Detectors such as:

  • Line coverage provides superior sensitivity.
  • Compatible with virtually any fire alarm control panel.
  • Alarm Point Location.
  • Suitable for installation in severe environmental conditions.
  • Easy to install, test, and splice.

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The Linear Heat Detection Cable (LHDC) System from Hochiki 

The Linear Heat Detection Cable (LHDC) System from Hochiki is designed to provide early detection of fire and overheating in circumstances where other forms of detection would not be viable, either due to inability to sustain the environment requirements or through prohibitive costs.

Extensive single zonal lengths of the specially designed LHDC may be installed with the ability to trigger alarms for hot spots occurring on very small sections of the overall cable and, providing the LHDC has not been subjected to excessive temperatures, the alarm condition can be reset at the zonal controller.




This module is designed to monitor a zonal length of Analogue Cable for both an elevated temperature (Fire) condition, and Fault Status (Open & Short Circuit).  It operates in conjunction with a single core coaxial cable and an end of line (EOL) terminator. The module provides early warning of hot spots and fire conditions on short sections of the overall zone length. Maximum Zone length for Analogue Linear Heat Detection Cable is 500m when connected to this module.



This Controller is designed to monitor a zonal length of resettable (Analogue) Linear Heat detection Cable (LHDC) for both an elevated temperature (Fire) condition and Fault Status (Open & Short Circuit).

The Controller offers two adjustable levels of alarm (A1 & A2), one of which may be optionally employed as a “Pre Alarm”. The LHDC is also monitored for fault conditions (open and short circuit).



This Controller has the same functionality as the LDM-519-SEN-N but with an additional output for the initiation of extinguishing media. This Actuation Output is primarily intended for the use with electrically operated chemical protractors (Metrons).

The unit also has fault monitoring circuitry appropriate to the series firing of these devices using an “All Fire” actuation loop configuration.


LHDC Analogue Cable

LHDC Analogue is a coaxial cable constructed with a copper coated steel central conductor, an inner insulation (dielectric), a tinned copper braid layer and an overall protective sheath.

The primary mechanism of heat (fire) detection is that the resistance of the dielectric, monitored between the central conductor and braid layer, has a negative temperature coefficient (NTC).




This module is designed to monitor a length of Digital Linear Heat Detection Cable (LHDC) for both fire condition and fault status (open circuit).  The unit is designed such that it may be configured to operate in a two wire mode that emulates the operation of conventional heat detectors.  The unit may therefore be directly interfaced with fire control panels by connection to fire zone trigger circuits or addressable interfaces.



This module features the same functionality as the LDM-519-DDL above, but is also certified to be fully compatible with SIL 2 certified systems.

Digital LHDC may be employed in lengths up to 2Km when using the LDM-519-DIM module. Signaling of fire and fault status is generated by means of volt free contacts.  The module has been specifically designed in a DIN rail format to allow it to be used in a variety of discrete housings or integrated multi zone control panels.


LHDC Digital Cable

Hochiki’s Digital Linear Heat Detection Cable is designed to provide early detection of Fire conditions and overheating in circumstances where other forms of detection would not be viable, either due to an inability to sustain the environment requirements or through prohibitive costs.

The primary mechanism of Digital LHDC is that the inner core insulating polymer is specially formulated such that it plasticizes at a specific temperature.

Read more here.