Why BS 6708 Type 830 Cable Still Powers South Africa’s Biggest Mining Machines

Why BS 6708 Type 830 Matters in South African Mining

South Africa’s mining industry has always been defined by scale, depth, and toughness. From the gold reefs of Gauteng, to the platinum belts of the Bushveld Complex, and the vast open-cast coal fields of Mpumalanga, mining operations here demand equipment—and power systems—that can withstand extreme conditions every single day.

Modern mining is no longer powered by small, stationary loads. Instead, large mobile machines such as draglines, bucket wheel excavators, and high-capacity shovels dominate both surface and underground operations. These machines require reliable medium-voltage power, delivered through flexible cables that must survive constant movement, dragging, twisting, and mechanical abuse.

This is where medium-voltage trailing cables play a critical role. Among them, the BS 6708 Type 830 cable has earned a long-standing reputation across African mining operations.

Originally developed under the British Standard BS 6708, Type 830 mining cables are specifically designed to supply power to large mining machines operating in harsh, dynamic environments. Despite the increasing use of SANS 1520-1 and IEC-based specifications in South Africa, BS 6708 Type 830 cables continue to be widely specified—particularly in legacy systems, export-driven projects, and multinational mining operations.

This article provides a deep, technical, and practical exploration of BS 6708 Type 830 mining cables, explaining how they are built, how they perform, and why they remain relevant in South African mining today.

Understanding the BS 6708 Standard

What Is BS 6708?

BS 6708 is a British Standard that specifies requirements for flexible trailing cables used in mining operations, quarries, and heavy industrial environments. These cables are commonly referred to as:

• Mining trailing cables

• Quarry cables

• Auxiliary mining cables

The standard focuses on mechanical robustness, electrical safety, and long service life under dynamic operating conditions.

Scope of BS 6708

BS 6708 covers cables intended for:

• Continuous movement during operation

• High mechanical stress (dragging, bending, twisting)

• Exposure to oils, moisture, abrasion, and UV radiation

• Supplying power to mobile and semi-mobile mining equipment

Type 830 sits at the heavy-duty end of this standard, designed specifically for medium-voltage applications supplying large mining machines.

BS 6708 vs SANS 1520-1 and IEC in South Africa

In South Africa, SANS 1520-1 is the dominant national standard for mining cables, supported by NRCS certification requirements. However, BS 6708 cables remain widely used due to:

• Existing installed base in older mines

• Compatibility with British-origin mining equipment

• Use in export-oriented mining projects across Africa

• Acceptance by multinational EPC contractors

In practice, many BS 6708 Type 830 cables are manufactured to meet or exceed equivalent IEC performance criteria, making them technically suitable for South African conditions when correctly specified.

Typical Applications of BS 6708 Type 830 Mining Cable

Trailing Cable for Large Mining Machines

BS 6708 Type 830 is primarily used as a medium-voltage trailing cable, supplying power to high-demand mining equipment such as:

• Draglines used in large open-cast coal operations

• Bucket wheel excavators in continuous mining systems

• Large continuous miners

• High-capacity electric shovels

These machines often operate far from fixed substations, requiring long trailing cable lengths capable of withstanding constant movement.

Open-Cast and Underground Suitability

Although more commonly associated with open-cast mining, Type 830 cables can also be used in certain underground applications where:

• Medium-voltage power is required

• Adequate space exists for bending radius compliance

• Mechanical protection and inspection regimes are in place

Mechanical Stresses in Real Mining Conditions

In South African mines, trailing cables are exposed to:

• Continuous dragging over rock and spoil

• Repeated bending around machine pivots

• Twisting due to machine rotation

• Impact from falling debris or vehicle traffic

The design of BS 6708 Type 830 directly addresses these stresses.

Cable Construction Overview

Conductor Design

BS 6708 Type 830 cables use electrolytic, stranded, tinned copper conductors manufactured to IEC 60228 Class 5 flexibility requirements.

Why tinned copper matters in mining:

• Improved resistance to corrosion

• Enhanced performance in humid and chemically aggressive environments

• Reduced oxidation over long service life

In South African mines—particularly coal and deep underground operations—humidity and corrosive conditions make tinned copper a practical advantage.

Insulation System

Each phase conductor is insulated with EPR (Ethylene Propylene Rubber).

Key benefits of EPR insulation:

• Excellent dielectric strength at 6.35/11 kV

• Stable performance under thermal stress

• High resistance to moisture ingress

• Superior ageing characteristics compared to PVC

The consistent 7.5 mm insulation thickness ensures controlled electrical stress and long-term reliability.

Screening System

Each insulated phase core is surrounded by a tinned copper and nylon braided screen.

The screening system serves several critical functions:

• Electrical stress control at medium voltage

• Enhanced personnel safety

• Compatibility with earth-fault detection systems

• Reduction of electromagnetic interference

In modern South African mines, effective screening is essential for compliance with safety and monitoring requirements.

Core Lay-Up

The cable consists of:

• Three screened phase cores

• Laid up around a bare copper earth conductor (where applicable)

• Compact circular formation

This configuration provides:

• Mechanical balance

• Resistance to deformation

• Stable geometry under repeated movement

Outer Sheath

The outer sheath is a heavy-duty chloroprene rubber (CR) compound.

Chloroprene offers excellent resistance to:

• Abrasion and tearing

• Oils, greases, and fuels

• UV exposure and weathering

• Ozone and harsh outdoor conditions

For South African open-pit mines, where cables are exposed to sunlight, dust, and temperature extremes, CR sheathing is critical.

Rated Voltage and Electrical Performance

BS 6708 Type 830 cables are rated at:

• Rated Voltage: 6.35/11 kV

• Test Voltage: 25 kV

This makes them suitable for medium-voltage power transmission to large mining machines with high power demand.

Compliance with BS 6708 ensures:

• Adequate insulation margins

• Controlled partial discharge risk

• Stable operation under load fluctuations

Technical Specifications

Available Conductor Sizes

Typical configurations include:

• 3 × 50 mm²

• 3 × 70 mm²

• 3 × 95 mm²

• 3 × 120 + 16 mm²

• 3 × 150 + 16 mm²

Selection depends on:

• Load current

• Trailing distance

• Ambient temperature

• Installation method

Conductor Stranding and Diameters

Fine stranding improves:

• Flexibility

• Bending performance

• Fatigue resistance

This is essential for trailing applications where cables are constantly in motion.

Insulation Thickness

A uniform 7.5 mm EPR insulation provides:

• Electrical stress control

• Reduced risk of insulation breakdown

• Long-term reliability at medium voltage

Earth Conductor Design

Larger sizes include a bare copper earth conductor (16 mm²), providing:

• Effective fault current return

• Enhanced system protection

• Improved earth continuity

Overall Dimensions and Weight

Depending on size:

• Overall diameter ranges from ~75 mm to 103 mm

• Weight ranges from 7.6 to 13.6 tonnes per kilometre

These factors influence:

• Drum selection

• Handling equipment

• Installation planning

Minimum Bending Radius

Minimum bending radius ranges from:

• 830 mm to 1,030 mm, depending on size

Respecting bending radius is critical to prevent:

• Insulation cracking

• Screen damage

• Premature cable failure

Electrical Parameters and Current Ratings

Continuous Current Ratings (25°C Ambient)

• 3 × 50 mm²: ~170 A

• 3 × 70 mm²: ~205 A

• 3 × 95 mm²: ~250 A

• 3 × 120 mm²: ~295 A

• 3 × 150 mm²: ~320 A

Impact of South African Climate

Higher ambient temperatures—common in Mpumalanga and Limpopo—require current derating to avoid insulation ageing and overheating.

Performance Advantages of BS 6708 Type 830

Key advantages include:

• Exceptional mechanical durability

• Stable medium-voltage electrical performance

• Long service life in harsh environments

• Reduced downtime and maintenance costs

For mines operating on tight production schedules, these advantages translate directly into improved profitability.

Installation and Handling Best Practices

Best practices include:

• Correct drum orientation during unreeling

• Avoiding excessive tensile loads

• Maintaining minimum bending radius

• Regular visual inspection during operation

Common Problems and Troubleshooting

Typical issues include:

• Outer sheath abrasion

• Insulation ageing due to overheating

• Screen damage affecting safety

• Earth continuity failures

Early detection through routine inspection is essential.

FAQ

Is BS 6708 Type 830 suitable for underground mines?
Yes, with proper space and protection measures.

How does it compare with SANS 1520-1 cables?
Technically similar, but SANS requires NRCS certification.

Can it be used with reeling systems?
Yes, when bending radius and tension limits are respected.

Expected service life?
Typically 5–10 years, depending on operating conditions.

How to derate current at high temperatures?
Consult manufacturer derating tables and site conditions.

Selecting the Right BS 6708 Type 830 Cable

Key selection factors:

• Correct conductor size

• Mechanical stress level

• Compliance documentation

• Experienced mining cable supplier

A Reliable Medium-Voltage Trailing Cable for South African Mining

The BS 6708 Type 830 mining cable remains a proven solution for powering large mining machines across South Africa. Its robust construction, stable electrical performance, and long service life make it a trusted choice in some of the world’s harshest mining environments.

For operations prioritising safety, reliability, and long-term performance, BS 6708 Type 830 continues to deliver—day after day, shift after shift.

Contact Anhui Feichun Special Cable Co., Ltd.

For comprehensive technical specifications and quotations, please contact our specialized mining cable engineering team:

Technical Engineering Support:

tech@feichuncables.com

Sales Engineering Department:

Li.wang@feichuncables.com

WhatsApp Contact:

Manufacturer: Anhui Feichun Special Cable Co., Ltd. (安徽飞纯特种电缆有限公司)

Manufacturing Headquarters: Building A, Private Science and Technology Park, Hefei Economic and Technological Development Zone, Anhui Province, People’s Republic of China

+86 17333223430