How BS 6708 TYPE 621 Cables Keep Excavators and Crushers Running

Introduction

Mining is the backbone of South Africa’s economy, with operations spanning gold, platinum, coal, and other minerals. These activities demand not only sophisticated machinery but also a reliable and robust electrical infrastructure. A single power disruption can halt an entire production line, resulting in costly downtime. This is where BS 6708 TYPE 621 cables play a pivotal role.

The BS 6708 standard, originating from the British Standards Institution, specifies requirements for flexible, heavy-duty power cables used in mining and industrial applications. These cables are engineered to withstand harsh environmental conditions, mechanical stress, and high currents, ensuring uninterrupted operations.

Among the BS 6708 family, Type 621 stands out as a high-voltage, heavy-duty cable, specifically designed for powering excavating machines, crushers, and other heavy-duty mining equipment. With a rated voltage of 3800/6600 V, it combines flexibility, mechanical robustness, and chemical resistance—key properties for South Africa’s underground and open-pit mines.

Keywords for this discussion include BS 6708 TYPE 621, mining cable South Africa, heavy-duty cable, and 3800/6600V cable, all reflecting its relevance in the local mining context.

Typical Applications in South Africa

BS 6708 TYPE 621 cables are widely used across South Africa’s mining landscape. They supply power to critical heavy machinery, from underground loaders to open-pit excavators, enabling continuous operation under extreme conditions.

Underground and Open-Pit Mining

In underground mines, such as those in the Witwatersrand gold belt, Type 621 cables supply rock crushers, shuttle cars, and drilling machines. The cable’s flexibility and mechanical strength allow it to be installed in dynamic environments, where equipment moves constantly.

In open-pit operations, like coal mining in Witbank, these cables power large shovels and mobile crushers. Here, UV resistance, oil resistance, and mechanical durability are essential, given the exposure to sunlight, chemicals, and abrasive surfaces.

Heavy-Duty Equipment

Type 621 is compatible with equipment operating at high currents, such as:

• Excavators and loaders: Often working in confined tunnels or irregular terrain.

• Crushers: Demanding continuous high-voltage supply to maintain production throughput.

• Conveyors and feeders: Where electrical integrity is crucial for safety and efficiency.

Advantages in Harsh Conditions

South African mines present a combination of high temperatures, abrasive surfaces, moisture, and chemical exposure. Type 621 excels due to:

• Abrasion-resistant outer sheath

• Flexibility for dynamic applications

• Mechanical and chemical resistance

Case Study: Witbank Coal Mine

A coal mine in Witbank installed 2 km of BS 6708 TYPE 621 cables to power its primary crushing station. Previously, frequent cable failures caused downtime of up to 12 hours per week. After switching to Type 621:

• Downtime dropped to less than 2 hours per month

• Maintenance costs reduced by 25%

• Operational safety improved due to reduced risk of exposed conductors

This illustrates the practical advantage of investing in high-quality mining cables.

Cable Structure and Materials

Understanding BS 6708 TYPE 621’s design is crucial for engineers, electricians, and procurement managers in mining operations.

Conductor

The conductor is electrolytic, stranded, tinned copper wire, compliant with IEC 60228 Class 5 standards. This ensures high flexibility, essential for applications with moving machinery.

Cross-section options include:

• 4×35 mm²

• 4×50 mm²

• 4×70 mm²

• 4×95 mm²

• 4×120 mm²

• 4×150 mm²

The stranded design allows bending without breaking, ideal for dynamic installations.

Insulation

Ethylene Propylene Rubber (EPR) is used for insulation. Key properties:

• 5 mm thickness providing high dielectric strength

• Thermal resistance for sustained operation in hot environments

• Mechanical and chemical resistance, protecting against oils, acids, and abrasives

This ensures consistent performance in both underground shafts and open-pit mines.

Lay-up and Bedding

Cores are laid over each other to ensure uniform stress distribution. The rubber-based bedding compound protects cores from mechanical damage, reducing the risk of conductor fatigue during installation or operation.

Armour

The cable features galvanized steel pliable armour, providing:

• Protection against crushing, impact, and abrasion

• Longevity in tunnels and over rugged terrain

• Compliance with mining safety regulations

Armour also contributes to grounding and reduces electrical interference in high-power applications.

Outer Sheath

The heavy-duty chloroprene outer sheath provides:

• Oil, water, and UV resistance

• Abrasion protection for harsh surface conditions

• Suitable diameters and bending radii for handling and installation

Overall, the structure balances flexibility, mechanical protection, and electrical integrity.

Technical Specifications

Mechanical Dimensions

Electrical Parameters

• Rated voltage: 3800/6600 V

• Test voltage: 15 kV

• Continuous current rating at 25°C ambient: 135–320 A depending on cross-section

• Maximum DC resistance of conductors and armour specified at 20°C

These specifications guarantee reliable high-power delivery across South African mining operations.

Compliance and Standards

• BS 6708 certification

• IEC 60228 Class 5 compliance for conductors

• Suitable for NRCS approval and South African mining regulations

This ensures regulatory compliance and operational reliability.

Advantages of BS 6708 TYPE 621 for Mining Applications

Type 621 cables provide significant benefits for mining operations:

1. Flexibility: Easy installation on dynamic equipment like loaders and conveyors

2. Mechanical robustness: Resistance to abrasion, impact, and crushing

3. Reliable power delivery: Reduces operational downtime

4. Chemical and moisture resistance: Suitable for corrosive and wet environments

5. Longevity: Durable under South African mining conditions

Investing in Type 621 enhances both productivity and safety, critical in high-risk mining areas.

Installation Considerations

Proper installation maximizes Type 621 cable lifespan:

• Bending radius adherence: Avoid kinks and mechanical stress

• Environmental conditions: Ensure temperature and chemical exposure limits are respected

• Compatibility: Works with cable reels, drag chains, and power distribution panels

• Maintenance: Regular inspection for mechanical damage, insulation wear, and armouring integrity

Correct installation ensures consistent power delivery and reduces maintenance costs.

Common Issues and FAQ

1. Can BS 6708 TYPE 621 withstand open-pit and underground conditions?

Yes, the combination of EPR insulation, steel armour, and chloroprene sheath ensures durability in harsh mining environments.

2. What is the maximum pulling length for this cable?

Pulling lengths depend on cross-section and installation method; consult technical guidelines to avoid conductor damage.

3. How often should the cable be inspected?

Visual and electrical inspections every 3–6 months are recommended in high-load operations.

4. Can it be used in high moisture or chemical exposure areas?

Yes, the cable is resistant to water, oils, acids, and mechanical wear.

5. Replacement tips and lifecycle considerations

Plan replacement during scheduled maintenance to prevent unplanned downtime. Typical lifecycle: 5–10 years depending on environmental stress.

6. Comparison with other BS 6708 types

Type 621 is suitable for high-current, dynamic equipment, while Type 506 or 512 may be better for lighter applications.

South African Case Studies

Witbank Coal Mining

• 2 km of Type 621 cables installed for primary crushers

• Resulted in 80% reduction in downtime

• Improved safety and reduced maintenance costs

Rustenburg Platinum Mine

• Installed to supply platinum smelting and processing equipment

• Flexible cable allowed dynamic movement of conveyors and crushers

• Operational efficiency increased by 15%, ensuring consistent production

These examples illustrate Type 621’s adaptability across different mining sectors.

Conclusion

BS 6708 TYPE 621 cables are a cornerstone for heavy-duty mining operations in South Africa. Their combination of flexibility, durability, mechanical strength, and chemical resistance makes them ideal for powering excavators, crushers, and other high-current equipment in both underground and open-pit environments.

Investing in Type 621 ensures operational continuity, reduced downtime, and enhanced safety, ultimately supporting South Africa’s mining productivity. For engineers, miners, and procurement specialists, understanding the technical, mechanical, and environmental benefits of Type 621 is essential for reliable power distribution in challenging mining conditions.

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