1. Introduction to 3.8/6.6kV Medium Voltage Cables

The 3.8/6.6kV voltage rating is a key entry point into the medium voltage (MV) cable classification and is more commonly associated with British standards, notably both BS6622 and BS7835 specifications. These cables serve as the foundation for power distribution systems requiring voltages above the extended low voltage range (1.9/3.3kV) but below the higher distribution voltages (6.35/11kV). The 3.8/6.6kV designation indicates cables designed for systems where the phase-to-earth voltage is 3.8kV and phase-to-phase voltage is 6.6kV, with a maximum system voltage (Um) of 7.2kV.

Applications for 3.8/6.6kV cables can benefit from the mechanical protection provided by their aluminium wire or steel wire armour (depending on single core or three core configurations). Such cables would be well suited to fixed installation power distribution, and providing power to heavy-duty static equipment as their rigid construction limits the bend radius. Beyond fixed installations, 6.6kV is used extensively in Marine applications and mobile offshore units, where cables tend to be supplied with tinned copper conductors and sheathing materials suited to the environmental challenges.

Source: Eland Cables – MV Armoured XLPE/SWA Cables

2. British Standards: BS6622 and BS7835

British Standards BS6622 and BS7835 are the primary specifications for medium voltage armoured cables in the UK and internationally. Both standards cover thermosetting insulated cables from 3.8/6.6kV up to 19/33kV but differ in their sheathing materials and fire performance properties.

Cable Construction (BS6622 / BS7835)

Source: Power and Cables – 6.6kV MV Cables Single Core

3. Complete 3.8/6.6kV Cable Product Range

A huge variety of power cables are available in the voltage 3.8/6.6kV, across material types and constructions to provide environmental protection and support installation design. The following table provides a comprehensive overview of all major cable types.

Source: Eland Cables – SANS Type 63 and Type 66 Cables

4. Mining Cable Applications: SANS Type 66

Flexible trailing cables such as the Type 66 cables are for opencast mining machinery including medium sized draglines, section feeders, shovels and drills. Also suitable for portable equipment, including those used in hazardous areas. The Type 66 cables have a voltage rating of 3.8/6.6kV and are manufactured in accordance with SANS 1520-2 (South African National Standard).

SANS 1520 Cable Type Classification

All cables offer good resistance to sunlight, UV radiation, and oils as well as being resistant to abrasions – all factors demanded of cables in the challenging environment of open cast and sub-surface mining operations.

Source: Eland Cables – SANS 1520 Cable

5. Marine & Offshore Applications: BS6883

Beyond the British standards for land-based applications, 6.6kV is used extensively in Marine applications and mobile offshore units. British Standard BS6883 covers the specifications for the shipboard fixed wiring of lighting, power, control, instrumentation and propulsion circuits with a voltage rating of up to 8.7/15kV. Like the Coil End Lead, marine cables tend to be supplied with tinned copper conductors and have sheathing materials suited to the environmental challenges.

BS6883 Cable Types for 3.8/6.6kV

Marine Cable Applications

Source: Cleveland Cable – BS6883 Cable

6. Technical Specifications for 3.8/6.6kV Cables

Insulation Thickness Requirements

Source: Tratos Group – IEC 60502 Standard

Operating Temperature Ratings

Current Ratings for 3.8/6.6kV Cables

Reference conditions: Ground temperature 20°C, soil thermal resistivity 1.5 K·m/W, burial depth 0.8m, conductor operating temperature 90°C.

3-Core 3.8/6.6kV XLPE/SWA Cables – Copper Conductor

Single Core 3.8/6.6kV XLPE/AWA Cables – Copper Conductor

7. Flexible Equipment Cables: Coil End Lead Type 4E

Other 3.8/6.6kV cables may be more flexible, such as the single core Coil End Lead Type 4E designed for motors, generators, actuators, transformers and circuit-breakers, with its CPE Rubber outer sheath. It should be noted that this cable is available in a range of voltages from 300/500V up to 11kV.

Coil End Lead Applications

8. Applications for 3.8/6.6kV Cables

9. Feichun Cable 3.8/6.6kV 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 3.8/6.6kV medium voltage cables for power distribution, mining, marine, and industrial applications.