Inside the Nerve System of Modern Mines: A Deep Dive into BS 6708 Type 506, 512, 518 & 524 Control Cables

Introduction

Modern mining is no longer driven solely by brute mechanical force. Behind every continuous miner, longwall shearer, crusher, or conveyor system lies a dense network of control and interconnection cables that transmit signals, commands, and feedback between machine sections and auxiliary systems. These cables do not carry megawatts of power—but without them, even the most powerful machine becomes unusable.

In deep-level and mechanised mining environments such as those found across South Africa, control cables must operate flawlessly under constant vibration, mechanical stress, moisture, dust, oil contamination, and electromagnetic interference. Any signal instability can result in equipment malfunction, unplanned downtime, or serious safety incidents.

This is where BS 6708 control cables have built a strong reputation. Within this standard, Type 506, 512, 518 and 524 are widely specified for use in large mining machines and heavy industrial systems requiring reliable control, signalling, and interconnection.

This article provides an in-depth technical and practical overview of BS 6708 Type 506–524 control cables, explaining how they are constructed, how they perform electrically and mechanically, and why they remain a trusted solution for South African mining conditions.

Understanding the BS 6708 Standard

BS 6708 is a British Standard developed for heavy-duty control and instrumentation cables, particularly where enhanced mechanical protection, screening, and durability are required. While originally developed in the UK, BS 6708 has gained international acceptance in industries such as mining, minerals processing, ports, and heavy manufacturing.

The design philosophy behind BS 6708 is clear:

• High mechanical robustness

• Stable electrical performance

• Effective electromagnetic screening

• Long service life in harsh industrial environments

In South Africa, BS 6708 cables are commonly accepted in mining and industrial projects because their construction aligns closely with local operational realities. Many mining OEMs and EPC contractors specify BS 6708 control cables for imported machinery, especially where British or European engineering heritage is involved.

Although BS 6708 is not a South African national standard, it is widely used alongside SANS practices, provided the cable design meets mine safety, reliability, and operational requirements.

Typical Applications in Mining and Heavy Industry

Control and Signalling in Large Mining Machines

BS 6708 Type 506, 512, 518 and 524 cables are primarily used as control and interconnection cables in large mining machines. Their role is to transmit low-voltage control signals between:

• Machine sections

• Control panels

• Sensors and actuators

• Auxiliary equipment

Typical mining equipment includes:

• Continuous miners

• Longwall shearers

• Crushers and feeder breakers

• Conveyor systems

• Mobile and fixed auxiliary systems

Remote Control and Automation

As South African mines continue to adopt mechanised and semi-automated systems, the importance of reliable control cabling has increased. These cables support:

• Remote start/stop circuits

• Interlocks and safety loops

• Sensor feedback (temperature, pressure, position)

• PLC and control system interconnections

Why Screened and Armoured Control Cables Are Preferred

Underground mining environments are saturated with high-power equipment, creating strong electromagnetic fields. Screened control cables reduce EMI and ensure signal integrity, while armour provides protection against crushing, abrasion, and accidental impact.

Cable Construction Overview

BS 6708 Types 506 / 512 / 518 / 524 share a common construction philosophy focused on mechanical protection and electrical stability.

Each layer of the cable is engineered to perform a specific function, working together to ensure reliable operation in demanding conditions.

The typical construction includes:

1. Fine-stranded tinned copper conductors

2. EPR or TPE insulation

3. Multi-core lay-up in contact

4. Tinned copper / nylon braided screen

5. Rubber-based bedding

6. Galvanised steel pliable armour

7. Heavy-duty chloroprene outer sheath

Conductor Design

Electrolytic, Stranded, Tinned Copper

The conductors are manufactured from electrolytic copper, ensuring high electrical conductivity. Stranding complies with IEC 60228 Class 5, making the conductors flexible enough for installation in moving or vibrating machinery.

Benefits of Fine Stranding

Fine stranding reduces internal stress during bending and vibration—critical in mining machines where cables are rarely static.

Advantages of Tinned Copper

Tin coating provides enhanced resistance to corrosion, especially in:

• Humid underground environments

• Areas exposed to water ingress

• Mines with chemically aggressive atmospheres

Insulation System

EPR vs TPE Insulation

BS 6708 control cables typically use EPR (Ethylene Propylene Rubber) or TPE (Thermoplastic Elastomer) insulation.

Both materials offer:

• Excellent dielectric strength

• Thermal stability

• Resistance to oil and grease

• Long-term ageing performance

Importance for Control Circuits

Stable insulation is critical for low-voltage control circuits, where even minor leakage or insulation degradation can cause false signals or system faults.

Core Identification and Lay-Up

Multi-Core Configurations

The cables are available in:

• 6 cores

• 12 cores

• 18 cores

• 24 cores

This allows engineers to select the appropriate configuration based on control complexity.

Laid Up in Contact

All cores are laid up in contact, resulting in:

• Compact overall diameter

• Improved flexibility

• Easier termination in control panels

Screening System

Tinned Copper / Nylon Braided Screen

A braided screen is applied over the laid-up cores, serving several critical functions:

• Reduces electromagnetic interference (EMI)

• Protects sensitive control signals

• Improves system reliability

Importance in Mining Equipment

High-power motors, variable speed drives, and switching equipment generate noise that can disrupt control circuits. Screening ensures clean and stable signal transmission.

Bedding Layer

A rubber-based bedding compound is applied over the screened cores. This layer:

• Cushions the cores

• Absorbs vibration

• Protects against mechanical stress

It also improves the flexibility of the cable while preparing a smooth surface for the armour.

Armour Design

Galvanised Steel Pliable Armour

The armour provides robust mechanical protection against:

• Crushing

• Impact

• Abrasion

Armour as Earth Continuity

In addition to mechanical protection, the armour acts as a reliable earth continuity path, enhancing safety in mining installations.

Outer Sheath Characteristics

Heavy-Duty Chloroprene (CR)

The outer sheath is manufactured from chloroprene rubber, chosen for its resistance to:

• Oils and greases

• Moisture and chemicals

• Mechanical damage and abrasion

Performance in South African Conditions

CR sheaths perform reliably across South Africa’s diverse mining climates—from humid underground gold mines to dusty open-cast operations.

Voltage Ratings and Electrical Performance

• Rated voltage: 320/550 V

• Test voltage: 1.5 kV

These ratings provide sufficient safety margins for low-voltage control and signalling applications in mining environments.

Technical Specifications Overview

Available configurations include:

• 6 × 1.34 mm²

• 12 × 1.34 mm²

• 18 × 1.34 mm²

• 24 × 0.93 mm²

Key construction details:

• Class 5 stranded conductors

• Consistent insulation thickness (0.4 mm)

• Robust inner and outer sheath dimensions

Mechanical Characteristics

• Minimum bending radius: 236–267 mm

• Approximate cable weight: 1.02–1.6 t/km

• Optimised balance between durability and handling

The combination of armour and CR sheath ensures long service life, even under harsh handling conditions.

Electrical Parameters in Detail

Continuous Current Ratings (25°C Ambient)

• 6 × 1.34 mm²: 16 A

• 12 × 1.34 mm²: 13 A

• 18 × 1.34 mm²: 11 A

• 24 × 0.93 mm²: 8 A

Voltage Drop and Resistance

Low DC resistance and controlled voltage drop make these cables suitable for long control runs without signal degradation.

Installation Considerations in Mining Operations

Best practices include:

• Maintaining minimum bending radius

• Proper clamping and routing

• Correct termination of screens and armour

• Ensuring effective earthing

Poor installation remains one of the leading causes of premature cable failure.

Performance in South African Mining Conditions

BS 6708 Type 506–524 cables have proven compatibility with:

• Continuous-duty mining operations

• High-vibration equipment

• Mechanised and automated systems

Their robust construction aligns well with South Africa’s demanding mining environment.

Comparison Between Types 506, 512, 518 and 524

Common Questions and Answers (FAQ)

Are BS 6708 control cables power cables?
No. They are designed for control and signalling, not power transmission.

Can they be used underground?
Yes, they are well suited for underground coal and hard rock mines.

Why is screening necessary?
To protect control signals from electromagnetic interference.

Are they suitable for moving equipment?
Yes, their flexible conductors and robust construction support dynamic applications.

Conclusion

BS 6708 Type 506, 512, 518 and 524 control cables represent a proven solution for control and interconnection in demanding mining environments. Their combination of mechanical strength, electrical stability, effective screening, and durable materials makes them a trusted choice for South African mining operations.

Selecting the correct configuration is not just a technical decision—it is a long-term investment in operational reliability, safety, and productivity.

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