The Honeywell System Sensor SS-LD-68-155 digital linear heat detection cable is engineered for seamless integration across industrial fire signaling networks. Operating as a normally-open circuit that activates via a short-circuit switch mechanism at 68°C (155°F), the cable provides direct electrical and hardware compatibility with both modern addressable building automation systems and legacy conventional initiating device circuits.
Fire Alarm Control Panel (FACP) Integration
The SS-LD-68-155 interfaces directly with intelligent, addressable systems and conventional fire alarm panels without requiring specialized proprietary host controllers:
- Addressable Systems: Fully compatible with Notifier and System Sensor intelligent fire alarm control panels when wired through standard intelligent addressable monitor modules. The monitor module senses the switch state changes, reporting localized alarm and trouble conditions directly onto the signaling line circuit (SLC).
- Conventional Systems: Compatible with conventional fire alarm control panels supporting standard normally-open dry contact initiating device circuits (IDC). When the heat-sensitive polymer melts under fire conditions, the tri-metallic cores short together to latch the conventional detection zone into an alarm state.
Supervisory and End-of-Line Requirements
Continuous circuit integrity and fault supervision require proper termination across every installed run:
- End-of-Line (EOL) Termination: An approved End-of-Line (EOL) box or zone-matching termination resistor must be installed at the distal end of the detection run. This allows the host panel or monitor module to maintain continuous open-circuit and short-circuit supervision.
- Fault Watch: The monitoring circuit detects opens (broken conductors or loose splices) as fault/trouble conditions, while distinguishing low-resistance short circuits (conductor contact at 68°C) as positive fire alarms.
- Post-Event Servicing: Because digital linear heat cable is non-restorable at the point of thermal activation, triggered sections must be spliced out using approved junction boxes.
Electrical Circuit Parameters
Designers must adhere to the following electrical operational thresholds when calculating zone limits and circuit power allowances:
- Operating Voltage: Rated for operational circuits up to 30 V AC and 42 V DC.
- Conductor Resistance: The twisted pair of tri-metallic cores exhibits a low electrical resistance of approximately 0.05 Ohm/ft.
- Capacitance & Inductance: Cable capacitance ranges from 88 to 150 pF/m (26 to 45 pF/ft), with an inductance rating of 540 to 1050 nH/m.
- Maximum Continuous Zone Length: Supports continuous zone deployments of up to 3,000 meters (10,000 feet) per monitored loop.
Structural & Physical Compatibility
The general-purpose red polypropylene outer jacket features a 1 kV tested protective outer coat, rated for operating environments from -40°C to +121°C and relative humidity levels between 90% and 98% (non-condensing). During routing along cable trays, conveyor belts, escalators, warehouse racking, cable tunnels, and vehicular tunnels, installers must strictly maintain the minimum bend radius of 50 mm to prevent physical conductor stress or false shorting.
Compatibility Reference Table
| Subsystem / Parameter | Specification / Compatibility Status |
|---|---|
| Addressable Interface | Compatible via Notifier & System Sensor intelligent monitor modules |
| Conventional Interface | Compatible with standard normally-open conventional zones |
| Supervision Hardware | EOL box / matching termination resistor required |
| Maximum Circuit Length | 3,000 m (10,000 ft) |
| Operating Limits | Up to 30 V AC, 42 V DC (-40°C to +121°C) |
| Standards Compliance | UL 521 Listed, FM Approved, CE Marked, RoHS Compliant |
