BS 6708 Type 70 & Type 71 320/550V Armoured Mining Power Cable for Excavating, Crushing Equipment & Coalface Lighting
APPLICATION：
Used for supplying excavating, crushing machines and equipment, as well as coalface lighting.
Cable Structure:
CONDUCTOR : Electrolytic, stranded, tinned copper wire IEC 60228 Class 5
INSULATION : EPR
LAYUP : All cores are laid up in contact with each other.
BEDDING : Rubber based bedding compound.
ARMOUR : Galvanized steel pliable armour.
OUTER SHEATH : Heavy duty chloroprene outer sheath.
Cable Properties:
RELATED STANDARDS : BS 6708
RATED VOLTAGE : 320/550 V
TEST VOLTAGE : 1.5 kV
Technical Specifications:
Cross Section | 4×4 | 5×4 | |
|---|---|---|---|
Conductors | |||
Number and cross section | mm2 | 4×4 | 5×4 |
Insulation thickness | mm | 1.0 | 1.0 |
Cable details | |||
Radial thickness of inner sheath | mm | 2.0 | 2.0 |
Min. inner sheath diameter | mm | 15.8 | 17.2 |
Max. inner sheath diameter | mm | 17.8 | 19.2 |
Size of armour | mm | 7/0,45 | 7/0,45 |
Outer sheath thickness | mm | 2.5 | 2.5 |
Min. overall diameter | mm | 23.5 | 24.9 |
Max. overall diameter | mm | 26.0 | 27.4 |
Min. bending radius | mm | 234 | 247 |
Max. pulling tension | kgf | 96 | 100 |
Appx. cable weight | kg/km | 1.1 | 1.23 |
Copper weight | kg/km | 154 | 192 |
Electrical details | |||
“Continuous current rating at 25°C Ambient” | A | 28 | 28 |
Max. DC resistance at 20°C | |||
Phase Conductor | Ω /km | 5.09 | 5.09 |
Armour | Ω /km | 5.07 | 4.63 |
How Do Type 70 & Type 71 Differ from Other BS 6708 Mining Cables?
Choosing the right cable requires understanding subtle differences between types:
Feature | Type 70 | Type 71 | Type 20/21 (for comparison) |
|---|---|---|---|
Core Configuration | 4×4 | 5×4 | 2–5 cores |
Rated Voltage | 320/550V | 320/550V | 640/1100V |
Armour | Galvanized steel pliable | Galvanized steel pliable | Galvanized steel |
Typical Use | Excavating, crushing, coalface lighting | Excavating, crushing, coalface lighting | Heavy-duty machinery |
Flexibility | High | High | Moderate |
In summary, Type 70 & 71 are optimized for medium-voltage mining operations with high flexibility and mechanical protection, making them ideal for coalface lighting and machinery where frequent movement occurs.
What Are the Primary Applications of BS 6708 Type 70 & Type 71 Cables?
BS 6708 Type 70 & 71 cables are widely used in mining operations for power supply where durability, safety, and compliance with BS 6708 standards are critical.
Key Applications:
Excavating Machines:
Provides reliable power to continuous miners, roadheaders, and shuttle cars.
Crushing Equipment:
Powers crushers and conveyors, often exposed to mechanical stress and vibration.
Coalface Lighting:
Ensures safe illumination in active working faces, critical for worker safety and operational efficiency.
South African Case Study:
In a Mpumalanga coal mine, BS 6708 Type 71 cables have been used for over 5 years supplying continuous miners. These cables demonstrated superior flexibility and resistance to mechanical damage, reducing downtime caused by cable failure.
How Should BS 6708 Type 70 & Type 71 Cables Be Installed?
Proper installation is essential to maximize lifespan and safety:
Pulling and Bending:
Observe minimum bending radius (234 mm for Type 70, 247 mm for Type 71).
Avoid sharp bends or kinks to prevent conductor and insulation damage.
Mechanical Protection:
Ensure the steel armour is fully embedded to resist crushing or impact.
Use proper clamps and cable trays for overhead or underground installation.
Termination:
Use BS 6708-compliant lugs and gland kits for secure termination.
Ensure tight sealing of armour and outer sheath to prevent moisture ingress.
Testing After Installation:
Conduct insulation resistance tests to detect damage incurred during installation.
What Are Common Issues and FAQs About BS 6708 Type 70 & Type 71 Cables?
Can I Use Type 70 for High-Voltage Applications?
No. Type 70 and 71 are rated for 320/550V, not for higher voltage machinery. For 640/1100V or above, consider BS 6708 Type 20 or Type 21.
How Long Do These Cables Last in Mining Conditions?
With proper installation and regular inspection, Type 70 & 71 cables can last 7–10 years, even under heavy mechanical stress. Regular maintenance is critical to prevent abrasion, insulation cracking, and armour corrosion.
How Do I Decide Between Type 70 and Type 71?
Type 70 (4×4 cores): Suitable for standard excavating and lighting setups.
Type 71 (5×4 cores): Used where an additional control or auxiliary circuit is needed.
Are These Cables Compliant With South African Safety Standards?
Yes. BS 6708 is recognized internationally, and these cables meet SANS-aligned safety standards when properly installed. Their tinned copper conductors resist corrosion in humid underground environments.
How Do BS 6708 Type 70 & Type 71 Perform Compared to Other Mining Cables?
Feature | Type 70 & 71 | Generic Armoured 320/550V | Type 20/21 |
|---|---|---|---|
Flexibility | High | Medium | Low |
Armour Strength | Good | Medium | High |
Installation Ease | Easy | Moderate | Moderate |
Resistance to Mechanical Damage | High | Medium | High |
Ideal Application | Excavating, lighting | Light machinery | Heavy machinery |
This comparison highlights why Type 70 & 71 are preferred for medium-duty, flexible mining operations.
Why Choose BS 6708 Type 70 & Type 71 Cables Today?
For mining companies in South Africa and worldwide, BS 6708 Type 70 & 71 cables provide a reliable, durable, and flexible solution for excavating machinery and coalface lighting. Investing in these cables reduces downtime, enhances worker safety, and ensures compliance with international safety standards.
Contact your authorized supplier today to select the right type, core configuration, and installation kit for your mining operation. Ensure your operations run smoothly and safely with BS 6708 mining cables.
