Introduction: Why Type 66 Cables Matter in South African Mining

If there is one cable model that South African mines consistently rely on for medium-voltage mobile power distribution, it is the SANS Type 66 / 66-ECC 3.8/6.6 kV Cable. From the manganese stretch of the Northern Cape to the deep-level platinum mines of Rustenburg and the massive open-cast pits of Mpumalanga, this cable has earned a reputation as the region’s most trusted MV trailing cable.

South African mining is unlike mining anywhere else. Our sites come with abrasive terrain, aggressive environments, deep underground humidity, high mechanical tension, frequent dragging cycles, and unpredictable thermal stress. Mines here need cables that bend, flex, twist, get dragged across sharp rock, get covered in diesel and mud, and still maintain electrical stability.

This is why the mining sector depends on medium-voltage flexible rubber cables, particularly the Type 66 series.

Why Type 66 is important

• It is one of the few cable types specifically engineered for mobile equipment operating at 3.8/6.6 kV.

• It withstands frequent movement, harsh dragging, and irregular reeling cycles.

• It complies with South African safety norms such as:

  • SANS 1520-2 (flexible mining cables)

  • SANS 1411-1 (non-metallic sheaths)

  • SANS 1411-3 (resistance to oil, UV, and abrasion)

In an environment where a single cable failure can stop a dragline or shovel that costs R150,000–R400,000 per hour of downtime, choosing the right cable is a matter of safety and economics.

The goal of this article is straightforward:
👉 To unpack the full structure, materials, specifications, engineering choices, and real operational advantages of Type 66 and Type 66-ECC cables, using real South African case studies to provide authority and practical insights.

Construction and Design: What Makes Type 66 So Robust?

Understanding Type 66 begins with understanding its engineering anatomy. Every layer is designed to handle mechanical punishment and electrical stresses typical in South African mines.

Conductor System: Class 5 Tinned Annealed Copper

Type 66 cables use Class 5 flexible stranded tinned annealed copper conductors.

Why Class 5 flexibility matters

• Mobile mining equipment requires constant bending.

• Rigid conductors crack under continuous flexing.

• Class 5 stranding dramatically increases cable lifespan under trailing, looping, reeling, and festoon systems.

Why the copper is tinned

South African underground mines have:

• high humidity,

• acidic mine water,

• corrosive sulphide environments.

Tin coating protects the copper from:

• corrosion,

• oxidation,

• chemical attack.

This is critical for mines in Limpopo and Mpumalanga, where underground moisture is persistent.

Insulation Layer: EPR (Ethylene Propylene Rubber)

EPR is the premium insulation material for harsh mining applications.

Advantages of EPR

• Excellent thermal resistance up to 90°C continuous.

• Stable dielectric strength at medium voltage.

• Resistant to oil-water mixtures found in coal mines.

• Superior elasticity reduces crack formation.

Compared with PVC and XLPE:

• PVC cannot handle the mechanical abuse or temperature swings.

• XLPE performs well electrically, but is too stiff for heavy trailing applications.

For mining, flexibility is as important as insulation strength, making EPR the top choice.

Pilot Cores: EPM Insulated Monitoring Cores

Type 66 includes three pilot cores, each insulated with EPM rubber.

Their functions

• Monitoring electrical faults

• Interlocking with mining machines

• Ensuring equipment trips when a fault occurs

• Communication or signalling

Why pilot-core size matters

The fault-loop impedance must be low enough to guarantee rapid earth-leakage protection.
Mines with long cable runs (common in draglines) rely heavily on accurate pilot-core performance.

Difference between Type 66 and Type 66-ECC

• Type 66 = 3 power cores + 3 pilot cores

• Type 66-ECC = 3 power cores + 2 pilot cores + 1 dedicated ECC conductor

The ECC version is used when additional earth continuity is required.

Screening System

Each power core is individually screened using tinned copper or textile braid.

Purposes:

• Provides a return path for earth faults

• Reduces electromagnetic interference

• Maintains equal potential, especially in hazardous areas

• Ensures compliance with SANS 1520-2 for safety in methane-prone zones

This screening is crucial in:

• underground coal mines

• platinum and gold shafts with explosive risks

Sheathing and Reinforcement

The cable is sheathed with CR (Polychloroprene Rubber) both inside and outside.

Characteristics

• UV-resistant

• Oil-resistant

• Sunlight-resistant

• Flexible in cold temperatures

• Resistant to abrasion from sharp rocks

CR rubber is essential in surface mines where sunlight intensity is extreme (Northern Cape temperatures reach 40–45°C).

Reinforcement Braid

The core bundle is protected by an open nylon braid with 16+ strings.

It increases:

• tensile strength

• tear resistance

• life under dragging and reeling cycles

This is one reason why Type 66 cables regularly survive 3–5 years, even in aggressive applications.

Colour & Identification

Sheath: Black, industry standard.

Markings include:

• cable type

• voltage rating

• manufacturer

• year of production

• SANS standard reference

Proper markings prevent supply chain issues and ensure compliance during NRCS inspections.

Technical Specifications & Electrical Parameters

Type 66 / 66-ECC is engineered for U₀/U = 3.8/6.6 kV, adequate for medium-voltage machinery across South Africa.

Voltage and Temperature Ratings

• Rating: 3.8/6.6 kV

• Operating temp: –25°C to +90°C

• Minimum bending radius: 6 × OD

These parameters ensure stable performance under thermal cycling typical in mobile machinery.

Conductor Sizes & Dimensions (25–240 mm²)

Common sizes:

• 25 mm² (small drills, light feeders)

• 50–95 mm² (medium draglines)

• 120–240 mm² (shovels, high-power feeders)

Larger sizes reduce:

• voltage drop

• cable heating

• fault-loop impedance

Correct sizing is essential in mines with long travel distances.

ECC Dimensions (66-ECC Only)

ECC sizes range from 16 mm² to 120 mm².

Why ECC improves safety

A large ECC dramatically improves:

• fault clearance times

• earth-fault sensitivity

• compatibility with modern protection relays

Mining companies upgrading from older cable models often choose Type 66-ECC specifically for this reason.

Electrical Characteristics Explained

Key parameters include:

DC Resistance

Decreases with larger conductor size and lower temperature.
Low resistance prevents excessive heating during long cycles.

Reactance & Impedance

Critical for power quality on large machines.
Lower impedance = faster fault response.

Current Carrying Capacity

Ranges from approx. 50 A (25 mm²) to over 250 A (240 mm²) depending on mine ambient temperature.

Short-Circuit Rating (1s)

Determines how the cable handles fault currents during protective trip delays.

Screen Resistance

Directly affects earth continuity.
Lower screen resistance = safer cable operation.

Application Scenarios in South African Mining

Type 66 is specifically designed for dynamic, high-stress applications.

Mobile Mining Machinery

• Section feeders

• Medium-sized draglines

• Electric shovels

• Drills

These machines consume large amounts of power and frequently move, requiring robust flexible MV cables.

Underground Environments

Used for:

• portable mining equipment

• drill rigs

• coal cutters

Type 66 performs well even in:

• oil-water mixtures

• high humidity

• abrasive tunnel walls

Surface Mines & Processing Plants

CR rubber provides protection from:

• sunlight

• diesel spills

• hot metal surfaces

• crushing loads

Open-cast mines in Northern Cape and Limpopo rely heavily on these characteristics.

High-Risk Zones

In methane-prone coal mines:

• screens must maintain continuity

• insulation must withstand chemical exposure

Type 66 meets SANS requirements for safe operation in such zones.

Performance Advantages in Harsh African Conditions

Mechanical Strength

Nylon reinforcement braid + CR sheath = outstanding tear resistance during:

• dragging

• reeling

• tension surges

Electrical Safety

Advantages:

• stable earth-fault response

• strong EMC performance

• consistent pilot-core signals

These are essential for preventing electrical ignition in explosive zones.

Thermal Stability

EPR allows:

• 90°C continuous operation

• better thermal cycling

• lower ageing rate compared with PVC or HPDE

Chemical & Environmental Resistance

CR rubber provides resistance to:

• UV

• ozone

• oils

• solvents

Ideal for SA mining climates.

Lifespan & Total Cost of Ownership

Typical lifespan:

• 3–5 years in aggressive applications

• 5–8 years in moderate environments

Long lifespan reduces:

• downtime

• replacement costs

• safety incidents

Real South African Case

Northern Cape Manganese Mine — Dragline

Problem:
Severe abrasion from rocky terrain and high reeling tension damaged previous cables.

Solution:
Upgraded to Type 66 95 mm².

Results:

• 38% reduction in unscheduled downtime

• More stable earth-fault behaviour

• Lower heat generation during peak loading

Rustenburg Platinum Mine — Upgrading to Type 66-ECC

Problem:
High fault-loop impedance caused delayed protection trips, posing shock and fire risks.

Solution:
Replaced old trailing cables with 66-ECC (70 mm² power + 35 mm² ECC).

Outcome:

• 62% faster earth-fault clearance

• Improved interlocking reliability

• Zero cable-related safety incidents in 12 months

Mpumalanga Underground Coal Mine

Conditions:
High methane concentration + oil-water contamination.

Feedback after 18 months:

• EPR insulation resisted chemical degradation

• CR sheath remained intact despite diesel exposure

• Screen continuity remained stable for protection relays

This case highlights Type 66’s compatibility with hazardous environments.

How to Select the Right SANS Type 66 Cable

Factors to Consider

• Conductor size & loading

• Mechanical tension

• Cable movement pattern

• Need for ECC or pilot cores

• Environment: underground vs surface

Sizing Tips for SA Operations

• Always verify short-circuit rating.

• Choose ECC sizes that ensure compliant fault-loop impedance.

• Consider temperature derating in hot SA mines.

Compatibility Checks

• Protection relay settings

• Transformer impedance

• VSD harmonics

Proper compatibility prevents nuisance tripping and overheating.

Installation, Handling & Maintenance

Installation Best Practices

• Maintain minimum bending radius (6 × OD)

• Use rollers or cable handlers

• Avoid sharp rocks during dragging

• Ensure correct termination

Routine Maintenance

• Visual inspections

• Sheath integrity checks

• Earth continuity tests

• Pilot-core resistance testing

Common Failure Modes

• Screen strand breaks

• ECC overheating

• Sheath cuts from sharp rocks

• Pilot-core damage from excessive bending

How to Extend Cable Life

• Proper storage

• Avoid over-tension

• Use cable-management systems

Frequently Asked Questions

1. Difference between Type 66 and 66-ECC?
   66-ECC includes a dedicated Earth Continuity Conductor.

2. Can Type 66 be used in explosive zones?
   Yes—if installed per SANS 1520-2.

3. Typical lifespan?
   3–8 years depending on conditions.

4. Why EPR instead of XLPE?
   EPR is more flexible and durable.

5. How to size a 6.6 kV shovel cable?
   Consider current rating + voltage drop + tension limits.

6. What tests are required?
   Earth-continuity, insulation resistance, pilot-core integrity.

7. Is CR sheath UV resistant?
   Yes—tested under SANS 1411-3.

8. Can Type 66 be spliced?
   Not recommended in high-movement environments.

9. What causes ECC overheating?
   Undersizing or poor terminations.

10. How do pilot cores improve safety?
    Enable interlocks and fault monitoring.

Conclusion

The SANS Type 66 / 66-ECC 3.8/6.6 kV Cable stands as one of the most reliable and durable medium-voltage mining cables in South Africa. Its engineering—flexible Class 5 copper, EPR insulation, CR sheathing, robust screening, strong mechanical reinforcement—directly addresses the unique challenges of South African mining.

Whether powering draglines in the Northern Cape, shovels in Rustenburg, or underground coal machines in Mpumalanga, Type 66 proves itself again and again with long lifespan, reduced downtime, and outstanding electrical safety.

For mining operations that demand reliability, safety, and compliance with SANS standards, Type 66 and 66-ECC remain the workhorses that keep South Africa’s mining industry moving.

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