BS6387 Fire Rated Cable (2 Core) for Critical Alarm Circuits

Fire detection systems fail when the cables powering them collapse before evacuation is complete. That is the hard reality of standard wiring exposed to flame temperatures exceeding 950°C. A false economy. This 2-core fire rated cable is manufactured to maintain circuit integrity under direct fire, mechanical shock, and water spray conditions as defined in BS6387. It buys time when time is measured in seconds.

Circuit Integrity Under Catastrophic Conditions

BS6387 CWZ Compliance
Constructed to pass the most demanding protocol within BS6387: Category C (950°C flame), W (water spray at 650°C), and Z (mechanical shock at 950°C).
This means the cable continues transmitting signal during a fully developed fire, even when struck by debris or exposed to fire-sprinkler discharge. For the safety engineer, that translates directly to extended evacuation windows and reduced liability exposure.

Solid Plain Annealed Copper Conductor
Low oxygen content, high conductivity copper eliminates signal degradation over long distances. Minimal voltage drop compared to aluminum-clad alternatives.
Your alarm loop stays live across a sprawling industrial complex. Fewer boosters, fewer points of failure, less cable tray to inspect.

Low Smoke Zero Halogen (LSZH) Sheath Compound
IEC 61034 tested for smoke density. IEC 60754 tested for acid gas emission.
If the cable does burn, smoke opacity remains below transmittance thresholds that blind escape routes. Toxic gas concentrations stay within survivability limits. Human error, not asphyxiation, becomes the evacuation bottleneck.

Mica Glass Fire Barrier Tape
High-grade muscovite mica tape wrapped directly around each conductor. Acts as a refractory insulator.
Dielectric strength holds after the outer sheath carbonizes. No inter-core short circuits. The panel still sees the end-of-line resistor. No nuisance fault alarms triggered by the fire itself.

Technical Construction Table

Validated Applications

• Addressable & Conventional Fire Alarm Loops
  Sustains two-way communication between detectors, sounders, and the main panel when the building management system has flagged a compartment fire.

• Emergency Voice Communication Systems
  Powers emergency loudspeakers during phased evacuation in high-rise towers. Circuit integrity under water spray meets the requirement for “stay-put” policies.

• Industrial Refinery & Chemical Plant ESD Systems
  Halogen-free sheath eliminates corrosive gas release near sensitive process analyzers. Survives dry film coating oven fires and deluge system activation simultaneously.

• Tunnel Linear Heat Detection & Ventilation Controls
  Handles the 950°C hydrocarbon pool fire curve. Signal continuity allows jet fans to operate as designed before structural failure, a non-negotiable for tunnel design engineers.

• Marine & Offshore Platform Fire Zones
  Compatible with SOLAS requirements for safe return to port. LSZH chemistry reduces secondary damage to navigation electronics enclosures.

Certification & Testing Benchmarks

• ✅ BS6387: CWZ classification tested by UKAS-accredited laboratory
• ✅ IEC 60332-1: Vertical flame propagation resistance on single cable
• ✅ IEC 61034-2: Smoke density < 60% light transmittance
• ✅ IEC 60754-2: Acid gas emission < 0.5% (pH ≥ 4.3; conductivity ≤ 10 µS/mm)
• ✅ CE Marking under the Construction Products Regulation (CPR), Euroclass B2ca-s1a,d1,a1 (typical)
• ✅ ISO 9001:2015 certified manufacturing facility and batch traceability system
• ✅ RoHS 3 (EU 2015/863) compliant

Common Technical Inquiries

Q: Does CWZ certification mean the cable passes all three tests simultaneously, or independently?
BS6387 CWZ designation requires the same cable sample to endure all three fire conditions in sequence. First, the sample is subjected to 950°C direct flame (Category C) for a defined duration. While still at 950°C, water is sprayed directly on the assembly (Category W). Then, mechanical shock is introduced at 950°C (Category Z). A cable passing these sequentially on a single sample provides a more realistic simulacrum of a developing fire than products passing the protocols on separate specimens. Confirm with your supplier that test reports show sequential, not separate, compliance.

Q: What is the minimum bending radius during installation in tight containment near fire panels?
8 times the overall cable outer diameter is the standard permissible dynamic bend during pulling. Static bends after fixing can be tighter but should not induce sheath stress whitening. For a typical 2-core 1.5 mm² variant with an OD near 8 mm, you are working with a ~65 mm mandrel radius. Tighter bends compromise the mica tape registration. Once that refractory layer fractures, circuit integrity under Category Z shock testing will fail prematurely. Spiral-wrapped mica with a 20–30% overlap is what you want to specify for complex tray routes.

Q: Can you print “Fire Alarm Circuit – Do Not Disturb” in black on the red sheath at one-meter intervals?
Yes. Laser inkjet marking with high-adhesion LSZH-specified ink is standard for runs above 1,000 meters. We recommend white hot-foil printing for LSZH jackets intended for ammonia-rich environments, as some solvent-based inkjet chemistries exhibit premature chalking. Specify the exact legend and font height on the purchase order. No tooling charge for standard legends.