1. Introduction to 6.35/11kV British Standard Cables

The 6.35/11kV voltage rating is one of the most common medium voltage classifications used in the United Kingdom and countries following British Standards for electrical power distribution networks. British Standard cables BS6622, BS7835, and BS7870-4.10 are manufactured in voltages including 6.35/11kV for power distribution networks. These cables form the backbone of the UK electricity distribution infrastructure, connecting the National Grid to substations, commercial facilities, and residential developments.

The 6.35/11kV voltage is commonly associated with armoured cable – the aluminium wire armour (AWA) for single core cables and steel wire armour (SWA) for multicore cables providing robust mechanical protection that makes 11kV cables suitable for direct burial in the ground. These armoured MV mains power cables are more commonly supplied with copper conductors but they are also available with aluminium conductors upon request to the same standard.

2. British Standard Cable Comparison: BS6622 vs BS7835 vs BS7870-4.10

The three primary British Standards governing 6.35/11kV cables serve different applications and installation environments. BS6622 covers armoured cables with PVC or MDPE sheathing, BS7835 specifies LSZH (Low Smoke Zero Halogen) armoured cables for fire-sensitive locations, and BS7870-4.10 covers unarmoured cables primarily used by Distribution Network Operators (DNOs) in cable ducts.

Source: Eland Cables – BS6622 Standard Cable

3. BS6622 XLPE Armoured Cables (PVC & MDPE Sheath)

British Standard BS 6622 sets out the specifications and required tests for armoured cables (single core AWA and three core SWA) for cables designed for use in fixed installations including networks and industrial installations. Across all voltages, the most commonly specified is the BS6622 11kV cable. BS6622 is also commonly referred to by its construction in international markets as MV armoured XLPE/PVC/SWA/PVC and XLPE/PVC/AWA/MDPE.

4. BS7835 XLPE LSZH Armoured Cables (Halogen-Free)

The BS7835 cables are for mains power distribution projects, with the LSZH sheathing meaning it is CPR compliant to a higher classification than its PVC counterpart. The low smoke halogen free construction makes this cable ideal for use in public buildings, tunnels, metros, airports, and locations where fire, smoke emission and toxic fumes create a potential threat to life and equipment.

5. BS7870-4.10 & DNO-Approved Cables

BS7870 Part 4, section 4.10 covers single core cables for distribution utilities with extruded insulation up to and including 11kV and 33kV. The 11kV cables are often supplied and installed in triplex formation. The Distribution Network Operators (DNOs) who operate the UK electricity distribution system have their own cables manufactured generally in accordance with BS7870-4.10 but with bespoke specifications for metallic screen cross-sectional area and material thicknesses.

DNO-Approved 11kV Cable Specifications

Sources: Eland Cables – UKPN Cable, SSE Cables, SPEN Cables, ENW Cables

6. Complete 6.35/11kV Cable Product Range

7. Current Carrying Capacity (6.35/11kV Cables)

Current ratings for 11kV cables depend on installation method, cable construction, ambient temperature, and soil thermal resistivity. The following table provides reference values for BS6622 3-core copper cables in trefoil formation.

Reference conditions: Ground temp 20°C, Soil thermal resistivity 1.5 K·m/W, Burial depth 0.8m, Ambient air 30°C, Conductor 90°C

De-rating Factors

Source: Cables Britain – BS 6622 XLPE MDPE Cable

8. Installation Guidelines

Source: Power and Cables – BS7835 Cable

9. Feichun Cable 6.35/11kV Product Range

Anhui Feichun Special Cable Co., Ltd. (安徽飞纯特种电缆有限公司) manufactures a comprehensive range of 6.35/11kV British Standard cables for power distribution networks. Our product range includes BS6622 armoured cables with PVC and MDPE sheaths, BS7835 LSZH fire-safe cables, and cables manufactured to DNO specifications for UK distribution network operators.