Why High-Voltage Cable Standards Matter in South Africa

In South Africa’s mining and industrial sectors, reliability is not merely a preference—it is a lifeline. Few countries operate mines as deep, as hot, and as mechanically demanding as South Africa does. Whether it is a platinum dragline in Rustenburg, a gold mine shaft feeder in the Free State, or a movable drilling system in Mpumalanga’s open-cast pits, the electrical cable connecting the machine to its power source is expected to perform flawlessly under punishing conditions.

This is where SANS—the South African National Standards issued by the South African Bureau of Standards (SABS)—play a crucial role. These standards ensure that cables used in hazardous and high-load environments meet stringent requirements for safety, performance, and durability.

Among all the cable standards used in mining, SANS 1520 stands out as the backbone for flexible trailing cables, defining construction, materials, test requirements, and operational limits for both low-voltage and high-voltage cables.

Within SANS 1520 Part 2, the spotlight falls on the SANS Type 633 and Type 633-ECC flexible trailing cables at 19/33 kV. These extra-heavy-duty high-voltage cables power some of the largest movable machines in South African open-cast mines—draglines, shovels, drills, and electrically driven mobile plant.

This article delivers a comprehensive technical deep dive into the SANS 1520 standard and the 19/33 kV Type 633 / 633-ECC cables, showing why the country’s largest mining operations rely on them.

Understanding the SANS 1520 Standard

Overview of SANS 1520

The SANS 1520 series covers flexible trailing cables used in the mining environment. These cables must withstand:

• Abrasion

• Oil, UV, and chemical exposure

• Severe mechanical tension and flexing

• Harsh weather conditions

• Constant movement and impact loads

• Electrical stress at medium and high voltages

The standard is divided into three parts:

SANS 1520 Part 1 – Low-Voltage Cables

Covers flexible trailing cables at:

• 640 V / 1.1 kV

• 1.9 / 3.3 kV

Examples include Type 41, Type 61, and other low-voltage portable power cables widely used in South African underground mining.

SANS 1520 Part 2 – Medium- & High-Voltage Cables

Covers 3.8/6.6 kV up to 19/33 kV.

This part includes some of the most robust cable designs:

• Type 63

• Type 66

• Type 611

• Type 622

• Type 633 (and Type 633-ECC)

These power the largest machines in open-cast mining and heavy industrial plants.

SANS 1520 Part 3 – DC Cables

Covers trailing cables up to 1.5 kV DC, often used for battery-powered equipment in hazardous areas.

Key Technical Requirements in SANS 1520

SANS 1520 ensures cable designs meet strict criteria for:

• Conductor construction: Class 5 tinned copper for flexibility and corrosion resistance

• Insulation materials: EPR/EPM rubber compounds

• Semi-conductive screens: For controlled electrical stress

• Braid reinforcement: Nylon + tinned copper

• Mechanical strength: Specific tensile limits, minimum bending radius

• Electrical performance: Voltage withstand tests, screen resistance, current rating

• Environmental resistance: UV, ozone, oil, heat, cold

Compliance is verified through:

• Routine tests

• Type tests

• Sample tests

• Dielectric tests

• Tensile and tear strength tests

• Hot elongation tests

Why Part 2 Matters for Type 633 / 633-ECC

Part 2 lays the foundation for cables operating at 19/33 kV, making it directly applicable to Type 633 and Type 633-ECC. These cables must manage:

• High electrical stress

• Long trailing distances

• Frequent reeling and unreeling

• Sudden torque loads

• Extreme environmental exposure

Type 633 is therefore designed as an extremely robust, heavy-duty, mechanically reinforced power delivery cable.

SANS Type 633 / Type 633-ECC 19/33 kV Cable: Structure and Materials

SANS Type 633 is a flexible EPR-insulated, rubber-sheathed, screened trailing cable designed for high-voltage mobile equipment.

Below is a complete breakdown of its construction.

Conductor

• Class 5 flexible stranded tinned annealed copper

• Offers superior flexibility and resistance to corrosion

• Tinning helps in wet and chemically aggressive mining environments

The soft-annealed construction helps the cable cope with continuous bending cycles during reeling.

Insulation

• EPR (Ethylene Propylene Rubber) insulation

• Triple extruded with a semi-conductive core screen

• High dielectric strength

• Excellent thermal stability and water resistance

This triple-extrusion ensures better bonding between layers, reducing partial discharge and extending cable lifespan.

Braid Reinforcement and Sheaths

Braids

• Nylon / tinned copper wire braid

• Provides mechanical toughness and EMI shielding

Inner Sheath

• CR rubber (Polychloroprene)

• Resistant to oil, UV, abrasion, and ozone

Outer Sheath

• Polychloroprene (CR rubber)

• Designed to resist sunlight, mechanical wear, chemicals, and ground impact

Minimum Bending Radius

• 9 × overall diameter
  Proving its suitability for reeling operations.

Pilot Cores

• Insulated with EPM rubber

• Used for control, protection signalling, interlocks, or monitoring

ECC Variant

The Type 633-ECC replaces one pilot core with a tinned copper conductor used as:

• Earth Continuity Conductor (ECC)

• For improved fault-current return path

• Enhances electrical safety in large mining machines

Assembly

• Each power core is individually screened with tinned copper/textile braid

• Three screened power cores + three pilot cores (or 2 pilots + ECC) are laid up together

• Central fillers ensure roundness and stability

Dimensional Summary Table

A selection of the key sizes is included below (summarised from your reference):

Higher conductor sizes deliver higher current capacity and handle greater mechanical forces.

Electrical & Technical Specifications

Voltage and Temperature Ratings

• Voltage rating (Uo/U): 19/33 kV

• Operating temperature: –25°C to +90°C

The high temperature capability makes the cable suitable for the hot terrains of the South African interior.

Conductor Resistance, Reactance & Screening

Each conductor has specific resistance ratings at 20°C and 90°C.

Example:

• 25 mm²: 0.795 Ω/km at 20°C

• 120 mm²: 0.164 Ω/km at 20°C

Reactance remains low (0.119–0.155 Ω/km), supporting long trailing distances.

Screen Resistance

• Minimum combined screen resistance: 0.23–1.6 Ω/km

• With ECC included, total return-path resistance improves dramatically

• Lower screen resistance = better earth fault protection

Current Ratings

At 30°C ambient:

• 25 mm² ≈ 105 A

• 120 mm² ≈ 260 A

Short-circuit ratings (1 second):

• 25 mm²: 3.1 kA

• 120 mm²: 14.6 kA

Earth-fault capacity increases significantly for ECC variants.

Dimensional Specifications

Pilot cores remain at 16 mm² for most sizes, except ECC variants where dedicated ECC sizes range from 16 mm² to 70 mm².

Power core maximum wire diameter ranges from 0.41 mm to 0.51 mm depending on conductor size.

Applications in South Africa

Mining Applications

Type 633 is engineered for severe high-voltage mining operations such as:

• Open-cast draglines

• Large electric shovels

• Blast-hole drills

• Mobile substations

• Movable high-power crushing plants

• Section feeders

These machines require long trailing or reeling cables capable of handling extreme mechanical tension.

Industrial Applications

Beyond mining, the cable is widely used for:

• Portable high-voltage equipment

• Hazardous-area electrical systems

• Dockyards and industrial yards requiring flexible HV feeders

• Reeling and festoon operations with high mechanical load

Real Case in South Africa

1: Rustenburg Platinum Mine — Dragline Feeder Upgrade

A major platinum operation in Rustenburg upgraded from SANS Type 611 11 kV cables to Type 633 19/33 kV to improve dragline efficiency.
Result:

• 24% reduction in voltage drop

• 30% longer service life due to improved braid reinforcement

• Reduced unplanned downtime caused by cable failures

2: Free State Gold Mine — ECC Variant for Earth Fault Protection

A deep-level gold mine implemented Type 633-ECC for mobile drilling rigs.
Outcome:

• Improved earth-fault sensitivity

• Faster trip response times

• Enhanced worker safety and reduced arc-flash risk

• Simplified fault-finding using ECC continuity monitoring

The mine reported that ECC variants reduced cable-related safety incidents by nearly 40% in the first year.

Key Advantages of SANS Type 633 / 633-ECC Cables

High-Voltage Capability (19/33 kV)

Engineered for medium- and high-power applications.

Exceptional Flexibility

Class 5 copper + rubber insulation = ideal for reeling.

Rugged Mechanical Durability

Handles abrasion, tension, crushing, UV, oils, and chemicals.

Designed for Harsh South African Conditions

CR sheathing ensures long life under intense sunlight and heat.

Compliance with Local SANS Standards

Including SANS 1520-2, SANS 1411-1, and SANS 1411-3.

ECC Variant for Safety

Better earth-fault monitoring and lower return-path impedance.

Frequently Asked Questions (FAQ)

Can Type 633 be used in underground mines?

Not typically. These cables are designed for open-cast operations and large mobile machines. Underground mines usually use lower-voltage trailing cables like Type 41 or Type 61.

How does the ECC variant improve safety?

It provides a dedicated low-impedance earth return path. This ensures faster fault detection and safer operation of large HV machines.

What is the maximum reel length?

Depends on conductor size, drum capacity, and maximum tension; typically 100–500 metres.

How do I calculate the current rating for local mining equipment?

Use:

• Ambient temperature (30°C typical in SA)

• Conductor size

• Installation conditions (reeling, trailing, buried, etc.)
  Manufacturers provide derating tables.

What signs of cable wear should operators look for?

• Ovality from excessive crush

• Sheath cracking

• Hot joints

• Screen continuity issues

• Braid exposure

• Discolouration from overheating

Conclusion

The SANS 1520 standard plays a critical role in establishing safe, reliable mining cable designs throughout South Africa. Within this standard, SANS Type 633 and Type 633-ECC 19/33 kV cables stand out as the preferred solution for high-voltage mobile equipment in open-cast mining and heavy industrial environments.

These cables are engineered to endure some of the toughest conditions on Earth—sun, heat, dust, mechanical load, constant movement, and high electrical stress. From draglines in the North West to drilling rigs in the Free State, mines across South Africa trust Type 633 because it is built specifically for performance, safety, compliance, and longevity.

As the mining sector moves toward electrification, higher power demands, and smarter monitoring technologies, high-voltage trailing cables like Type 633 / Type 633-ECC will continue to play a critical role in powering South Africa’s most demanding operations.

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