1. Introduction to 12.7/22kV Medium Voltage Cables

The 12.7/22kV voltage rating is a commonly specified voltage for British Standard medium voltage cables and for international cables, particularly those used in static infrastructure and equipment cables for the mining industry. This voltage rating is most often associated with British Standard armoured cables BS6622 (PVC sheath) and BS7835 (LSZH sheath), but it is also found in other geo-specific national standards, including SANS (South African National Standards).

22kV cables, like their European voltage 20kV equivalents, are covered under International standard IEC 60502-2 — both 22kV and 20kV have a maximum rating voltage (Um) of 24kV. This makes the 12.7/22kV cables particularly versatile for installations across different regulatory environments while maintaining compatibility with international testing and certification requirements.

22kV Cable Specification Overview

22kV cables are traditionally specified with copper conductors, but aluminium conductors may also be considered where weight is a consideration but space restrictions are not. The range of 22kV cables includes three-core configurations, insulated and sheathed in PVC or LSZH — although MDPE (Medium Density Polyethylene) may also be used where a more robust, external application demands.

Whilst the British standard cables are provided mechanical protection with a rigid ring of steel wire armour as their common application sees them buried directly, this is not a mainstay of the voltage — the SANS 622 cable for example is for heavy-duty large moving apparatus and so has a reinforcement braid of nylon to make it more flexible, often used in the mining industry.

2. BS6622 XLPE PVC 12.7/22kV Armoured Cable

BS6622 is a British Standard covering PVC-sheathed medium voltage armoured cables. These cables feature cross-linked polyethylene (XLPE) insulation and are designed for power distribution in underground systems, suitable for direct burial installation in free-draining soil. The armour provides robust protection against mechanical stresses and potential damage from external forces.

BS6622 Applications

BS6622 armoured cables are primarily used for underground power distribution networks. The robust construction allows for direct burial in free-draining soil without the need for additional mechanical protection. Common applications include industrial power distribution, utility networks, and commercial building supplies where PVC sheathing is acceptable.

3. BS7835 XLPE LSZH 12.7/22kV Fire-Safe Cable

BS7835 is the Low Smoke Zero Halogen (LSZH) equivalent of BS6622, designed for installations where fire safety is paramount. These cables emit minimal smoke and no toxic halogen gases when exposed to fire, making them essential for tunnels, metros, airports, hospitals, and other public buildings.

BS7835 vs BS6622 Comparison

Sources: Eland Cables – MV Armoured Cable, Power & Cables – 22kV MV Cables

4. BS7870-4.10 DNO-Approved Unarmoured Cable

British Standard BS7870-4.10 covers Copper and Aluminium medium voltage cables used for the foundation of electricity supply from a distribution main. As medium voltage polymeric insulated cables, these distribution and power network cables are approved and supplied in various sizes for utility grid networks worldwide.

Copper vs Aluminium Conductor Variants

DNO (Distribution Network Operator) Approvals

BS7870-4.10 cables are approved by UK Distribution Network Operators including UKPN, SSE, National Grid Energy Distribution (NGED), Northern Power Grid (NPG), Scottish Power Energy Networks (SPEN), and Electricity Northwest (ENW). Each DNO may have bespoke specifications for metallic screen cross-sectional area and material thicknesses.

Sources: Eland Cables – BS7870-4.10 Cable, Tratos Group – MV Energy Cables DNO

5. SANS Type 622 / 622ECC 12.7/22kV Mining Cable

SANS Type 622 cables are designed for heavy-duty mining applications under South African National Standards (SANS 1520). Unlike the rigid armoured British Standard cables, Type 622 features a reinforcement braid of nylon to provide flexibility for large moving apparatus in open-pit mining operations.

Mining Equipment Applications

Sources: Eland Cables – SANS Type 611/622/633 Cables, Eland Cables – SANS 1520 Cable

6. Complete 12.7/22kV Cable Comparison

7. Technical Specifications

Conductor Size Availability

22kV single core cables are available in the following cable conductor cross-sectional areas: 70mm², 95mm², 120mm², 150mm², 185mm², 240mm², 300mm², 400mm², 500mm², 630mm², 800mm², 1000mm². Three-core cables typically range from 35mm² to 400mm².

8. Installation & Application Guidelines

Critical Installation Notes

BS7870-4.10 cables are not suitable for installation by consumers — they are designed for utility network operators. The cables should not be installed at temperatures below 0°C without pre-conditioning. For mining applications with SANS Type 622 cables, proper cable management systems including cable reels and festoon systems are essential to prevent damage during equipment movement.