When to Use 318-B LSZH Flexible Cable Over Standard PVC Flexible Cable
318-B Low Smoke Zero Halogen (LSZH[1]) flexible cable must be specified over standard PVC flexible cable (318-Y) in high-occupancy, enclosed, or poorly ventilated environments where fire safety is a critical design requirement. Manufactured in compliance with BS EN 50525-3-11 (formerly BS 6500), 318-B cables feature cross-linked or thermosetting LSZH insulation and bedding, ensuring zero toxic halogen gas emission (under IEC 60754-1/2) and minimal smoke density (under IEC 61034-2) during combustion. Standard PVC cables release toxic hydrogen chloride (HCl) gas and dense black smoke when exposed to fire[1], obscuring exit routes and posing lethal inhalation hazards to occupants and equipment corrosion risks.
Technical Comparison: 318-B LSZH vs. Standard PVC (318-Y) Flexible Cable
| Technical Parameter | 318-B LSZH Flexible Cable | Standard PVC Flexible Cable (318-Y) | Applicable Standard |
|---|---|---|---|
| Rated Voltage (U0/U) | 300/500 V | 300/500 V | BS EN 50525 series |
| Conductor Material | Class 5 Flexible Plain Annealed Copper | Class 5 Flexible Plain Annealed Copper | IEC 60228[2] / BS EN 60228 |
| Operating Temperature Range | -5 °C to +90 °C (or +70 °C spec dependent) | -5 °C to +70 °C | BS EN 50525-3-11 / BS EN 50525-2-11 |
| Acid Gas Generation (HCl) | < 0.5% (Zero Halogen) | 15% – 25% (Halogenated) | IEC 60754-1 / IEC 60754-2 |
| Smoke Emission Light Transmittance | ≥ 60% (Low Smoke) | < 30% (Dense Smoke) | IEC 61034-2 / EN 61034-2 |
| Flame Propagation Rating | Flame Retardant[3] | Standard Flame Retardant[3] | IEC 60332-1-2 / EN 60332-1-2 |
| Corrosivity to Sensitive Electronics | Non-corrosive | Highly Corrosive (HCl acid formation) | IEC 60754-2 |
Primary Application Scenarios for 318-B LSZH Cables
- Public Infrastructure & High-Occupancy Buildings: Essential for airports, railway stations, hospitals, schools, and high-rise commercial structures where rapid evacuation is hampered by smoke visibility loss.
- Data Centers & Server Rooms: Prevents acidic HCl gas emissions from corroding delicate circuit boards, microprocessors, and copper busbars in the event of a localized electrical fire.
- Underground Transport & Marine/Offshore Environments: Mandatory under local building regulations and maritime safety codes for enclosed, poorly ventilated spaces with limited egress points.
- HVAC & Commercial Lighting Interconnections: Ideal for flexible connections to light fittings, appliances, and control gear installed in plenum spaces or air handling ducts.
CJDL CABLE Engineering Insight
For enclosed and high-occupancy installations where smoke and halogen toxicity threaten evacuation, 318-B LSZH is the engineering-specified choice over standard PVC. All 318-B flexible cables manufactured by CJDL CABLE are tested to BS EN 50525-3-11, IEC 60754-1/2, and IEC 61034-2, with routine verification of zero-halogen and low-smoke performance. In confined plenum and HVAC interconnections, CJDL CABLE 318-B maintains exit-route visibility and protects sensitive electronics without compromising flexibility.
References
- [1] Wikipedia. Low smoke zero halogen [EB/OL]. 2026-08-31.
- [2] Wikipedia. IEC 60228 [EB/OL]. 2026-08-31.
- [3] Wikipedia. Flame retardant [EB/OL]. 2026-08-31.