BS 7835 standard low-smoke halogen-free medium-voltage cables use XLPE cross-linked polyethylene insulation and have a rated voltage of up to 19/33kV. They are specifically designed for environments with extremely high fire resistance requirements. Their low-smoke halogen-free sheath significantly reduces smoke and toxic gas emissions in the event of a fire, ensuring safety and reliability. They are widely used in public buildings, transportation systems, industrial facilities, and infrastructure projects where high safety, durability, and other requirements are necessary.
BS 7835 Cable Structure
Conductor: Stranded annealed copper conductor, compacted or circular, manufactured in accordance with relevant IEC/BS standards to ensure excellent electrical conductivity and mechanical strength.
Conductor Screen: A semi-conductive layer applied over the conductor to provide a smooth electrical field and reduce electrical stress.
Insulation: XLPE (Cross-linked Polyethylene) insulation, offering high dielectric strength, thermal stability, and long-term reliability for medium voltage applications up to 19/33kV.
Insulation Screen: Semi-conductive insulation screen combined with a metallic screen to ensure uniform electric field distribution and effective grounding.
Metallic Screen: Copper tape or copper wire screen, providing fault current protection and electromagnetic shielding.
Inner Sheath (if applicable): LSZH compound inner sheath, offering low smoke emission and zero halogen characteristics.
Outer Sheath: Low Smoke Zero Halogen (LSZH) outer sheath, compliant with BS 7835, designed to minimize smoke density and toxic gas release in the event of fire.
Technical Parameters
| Item | Value |
| Rated Voltage (U₀/U) | 3.8/6.6kV – 19/33kV |
| Maximum System Voltage (Um) | Up to 36kV |
| Rated Frequency | 50 / 60 Hz |
| Conductor Operating Temperature | +90°C |
| Short Circuit Temperature (5s) | +250°C |
| Insulation Resistance | XLPE high insulation resistance |
| Bending Radius | ≥ 15 × overall diameter |
| Fire Performance | BS 7835 compliant |
| Halogen Content | IEC 60754-1 & 60754-2 |
| Smoke Density | IEC 61034 |
Applications
The BS 7835 LSZH Medium Voltage Cable up to 19/33kV is designed for power distribution systems where fire safety, low smoke emission, and reduced toxic gas release are essential. It is suitable for use in:
- Public buildings (hospitals, schools, airports)
- Underground transportation systems (metro, tunnels, railways)
- Power plants and substations
- Industrial facilities and infrastructure projects
- Commercial buildings with high fire safety requirements
This cable is especially recommended for enclosed or densely populated areas, where compliance with British flame-retardant standards is required.
Advantages
Enhanced Fire Safety
Complying with BS 7835 flame retardant requirements, the cable effectively limits flame spread and maintains safer operating conditions during fire incidents.
Low Smoke Zero Halogen (LSZH) Performance
The LSZH sheath significantly reduces smoke density and eliminates halogen acid gas emission, improving visibility and reducing corrosion risks in enclosed spaces.
Suitable for Medium Voltage Systems up to 19/33kV
Designed for reliable power transmission in medium voltage networks, including 6.6kV, 11kV, and 33kV power systems.
High Electrical Reliability
XLPE insulation provides excellent dielectric strength, thermal stability, and long-term performance under continuous electrical stress.
Ideal for Public and Infrastructure Projects
Widely used in transportation systems, public buildings, and critical infrastructure, where strict fire safety and British standard compliance are required.
Long Service Life and Low Maintenance
Robust construction and quality materials ensure stable operation, reduced maintenance costs, and extended service life.
Compliance with International Testing Standards
Tested according to relevant IEC fire, smoke, and halogen standards, making it suitable for international projects and export markets.