The BS 6387 standard defines performance requirements for Fire Resistant cables, especially critical in fire alarm, emergency lighting, and life‑safety circuits. Among its classifications, BS 6387 CWZ fire resistant cables represent the highest assurance of circuit integrity under extreme conditions.
BS 6387 is a UK‐based test standard specifying three key survival categories:
C (fire): 950 °C flame for 3 hours under load
W (water + fire): 650 °C flame 15 min, then water spray 15 min
Z (shock + fire): 950 °C flame for 15 min with mechanical impact every 30 s
The CWZ rating mandates passing all three tests, making it the most stringent classification.
Category C: Cable carries rated current under direct flame at 950 °C ±40 °C for 3 hours.
Category W: Flame at 650 °C for 15 minutes followed by spray water for another 15 minutes.
Category Z: Flame at 950 °C for 15 minutes, while the cable on an S‑bend is struck every 30 seconds by a steel bar the same diameter.
Ensures circuit integrity under extreme conditions – vital for emergency systems.
Delivers mechanical resilience in high‑stress environments like lifts and industrial setups.
Offers fire + water resistance – crucial in sprinkler‑protected buildings.
Typical BS 6387 CWZ fire resistant cables use:
Conductors: Stranded copper
Insulation: Mica + XLPE
Sheath: LSZH (Low Smoke Zero Halogen)
Fire alarm, voice alarm, emergency lighting
Infrastructure: skyscrapers, hospitals, tunnels
Industrial: oil & gas, transport, power plants
Harmonization: BS 6387 complements IEC 60331, BS 5839, and BS 5266
Risk mitigation: Enhances safety by delaying circuit failure and fire spread
Regulatory compliance: Mandated in the UK and many regions for life‑safety wiring
