What Are the Indicators of Mechanical Damage in Mining Flexible Cables?

In South Africa’s demanding mining sector—whether it’s the gold veins of Gauteng or the deep platinum shafts of North West—electrical infrastructure plays a silent but vital role. Flexible mining cables are the lifelines of modern mining equipment, powering everything from shuttle cars to continuous miners and jumbo drills. Yet, these cables face constant mechanical stress in hostile underground and open-cast environments.

Unfortunately, mechanical damage to flexible cables is not always immediately visible. Left unchecked, it can result in dangerous outcomes: arc faults, downtime, fire outbreaks, or even violations of regulatory frameworks like NRCS or the SANS 1520-1 cable safety standards. Early recognition of mechanical damage is essential to ensure safety, performance, and compliance across South African mining operations.

This article explores the key indicators of mechanical damage in mining flexible cables, offering practical insights and local examples to help you detect and prevent cable failures before they escalate.

Common Mechanical Stresses in Mining Environments

The mining landscape in South Africa is filled with abrasive surfaces, tight spaces, sharp turns, and heavy machinery. In such environments, flexible cables are constantly exposed to physical strain. Here are the most common sources of mechanical stress:

Dragging Over Rocks and Metal Surfaces

Cables often get pulled across rough rock faces, sharp metal edges, and abrasive terrain. This continuous dragging wears down the cable sheath and exposes internal insulation or conductors.

Crushing from Heavy Equipment

Mining trucks, loaders, and other machinery weighing dozens of tonnes can accidentally crush cables laid on the ground, leading to sheath flattening or internal conductor deformation.

Frequent Bending and Reeling/Unreeling

Reeling systems used in shovels, stackers, and draglines bend the cable repeatedly. Over time, this can lead to conductor fatigue or internal twisting.

Vibration and Movement in Mobile Machinery

Mobile mining machinery like drilling rigs or continuous miners subjects cables to intense vibration and irregular jerking, which accelerates wear and loosens internal assemblies.

These stresses cumulatively degrade cable integrity over time—sometimes with no visible signs until catastrophic failure occurs.

Key Indicators of Mechanical Damage in Flexible Mining Cables

Identifying mechanical damage before failure is possible if you know what to look for. Here’s a breakdown of five key signs:

3.1 Visible Outer Sheath Damage

Cuts, Abrasions, and Punctures

Cables with cuts or gouges in their outer sheath are immediately at risk. Even superficial damage can compromise insulation, particularly in damp underground environments.

Discoloration or Exposure of Inner Layers

If the outer sheath is worn to the point where coloured insulation or conductor braids are visible, the cable needs urgent replacement.

Melt Marks from Friction or Arc Faults

Friction against hot surfaces or minor arc flashes may cause localized melting. Such marks are an early warning sign of thermal or electrical hazards.

3.2 Irregular Cable Shape or Flattening

Flattened or Pinched Cable Sections

When a cable is flattened, often due to crushing or compression, the conductor strands inside may be compromised—even if the sheath seems intact.

Signs of Compression Under Machinery or Rock

Indentations or uneven surface texture suggest that the cable was pressed against a hard surface, weakening its internal structure.

3.3 Insulation Failure and Conductor Exposure

Cracks in Insulation

Small cracks in internal insulation materials may become visible when outer sheaths are damaged or split. These cracks increase the likelihood of phase-to-phase or phase-to-ground faults.

Exposure of Copper or Aluminium Conductors

If copper or aluminium strands are visible, the cable is already dangerously compromised.

Smell of Burnt Plastic or Rubber

Burning odours often precede visible smoke or sparks. This is usually a sign that internal heating has begun due to increased resistance from broken strands or partial shorts.

3.4 Electrical Performance Changes

Sudden Drop in Voltage or Irregular Current Flow

Damaged cables often exhibit erratic electrical behaviour, including voltage drops, flickering lights, or equipment shutdowns.

Hot Spots During Operation

Thermal imaging may reveal abnormally hot segments along a cable’s length. These are indicative of internal conductor damage or insulation failure.

Breaks in Continuity

Simple tools like a multimeter or megger can detect breaks in electrical continuity—signs that a conductor may be severed or corroded.

3.5 Cable Stiffness or Brittleness

Cable Becomes Rigid in Cold Conditions

While cable flexibility naturally reduces at low temperatures, excessive stiffness could indicate internal damage. Damaged insulation materials or conductors lose flexibility.

Broken Flexibility from Internal Breakage

If a once-flexible section becomes permanently stiff or “dead,” internal conductor or armour breakage is likely.

Case Study: Damage Detection at a Rustenburg Platinum Mine

Background on Mining Operations

In 2024, a major platinum producer in Rustenburg reported recurrent issues with shovel performance on shaft level 3. The operation used Type 41 0.64/1.1kV flexible trailing cables across multiple electrically powered shovels.

Early Signs Missed

Operators reported minor heating on one of the cables and visible sheath grazes. These were dismissed as “normal wear.”

Failure Event

A shovel failed mid-operation, halting ore loading for six hours. An inspection revealed internal conductor breakage caused by continuous bending and undetected crushing. The arc flash nearly caused an underground fire, and NRCS inspectors flagged the site for poor maintenance records.

Resolution

The mine introduced weekly infrared inspections and began tagging cables with QR-based condition history. Damaged cables were rotated out immediately, and the site adopted smart cable systems for its critical applications.

This case highlights the danger of overlooking even minor signs of mechanical stress.

Tools and Techniques for Early Detection

Visual Inspections During Routine Checks

Simple but effective—visually inspecting cables for abrasions, cracks, bulges, or exposed cores can catch issues early.

Thermal Imaging for Hot Spots

Infrared cameras reveal areas of high heat—often the result of internal friction or electrical resistance from damaged conductors.

Cable Testers for Resistance and Continuity

Using megohmmeters, continuity testers, or voltage drop analysis tools helps identify internal failures invisible to the eye.

Use of Smart Cables with Real-Time Monitoring

A growing trend in South African mines is the deployment of smart mining cables. These come with embedded sensors for strain, temperature, and continuity. Mines in Mpumalanga and Limpopo have begun piloting these technologies in 2025 with great success.

Preventive Measures to Avoid Mechanical Damage

Prevention is far more cost-effective than repair. The following strategies have been recommended by South African mining safety officers and cable manufacturers:

Proper Cable Routing and Protectors

Using heavy-duty conduits or HDPE cable protection ramps in high-traffic zones reduces mechanical contact damage.

Reeling Systems to Reduce Dragging

In mobile equipment, high-quality reeling systems ensure the cable doesn’t scrape or catch on rocks and track edges.

Training Staff to Handle Cables Properly

Improper pulling, bending, or coiling techniques are major contributors to internal cable damage. A quarterly training module is now a best practice among SANS-compliant mines.

Regular Maintenance and Audits

Scheduled cable audits (monthly visual and quarterly electrical) ensure early detection and compliance with SANS 1520-1 cable durability requirements. Maintenance records also serve as documentation during NRCS inspections.

Frequently Asked Questions (FAQs)

Q1: Can a cable still function with a damaged sheath?

Yes, but it’s unsafe. A damaged sheath exposes internal insulation to moisture, dust, and mechanical stress, increasing the chance of electrical failure or short circuits.

Q2: How often should cables be inspected in underground mines?

Visual inspections should occur weekly. Electrical and thermal testing should occur at least once per quarter, or immediately after any reported abnormal behaviour.

Q3: Are there cable types more resistant to mechanical stress?

Yes. Cables like SANS Type 41 and Type 63 with reinforced synthetic elastomer sheaths and braided copper screens offer higher resistance to abrasions and impact.

Q4: What SANS standard applies to mechanical durability?

SANS 1520-1 outlines mechanical and electrical performance criteria for mining cables. Section 6 of the standard specifically refers to mechanical endurance under tensile and crush forces.

Q5: How do I report or document mechanical damage for NRCS compliance?

Log the fault with cable ID, date, type of damage, environmental conditions, and action taken. This documentation helps during NRCS audits and improves maintenance tracking.

Conclusion

Mechanical damage to flexible mining cables is a silent but serious threat in the South African mining industry. While it may start small—an abrasion here, a flattened cable section there—it can quickly escalate into costly downtime or even life-threatening hazards.

The good news is that with vigilance, proper training, regular inspections, and adoption of smart cable technologies, these threats can be identified and managed early. South African mines are already leading by example, integrating durable cable solutions and predictive maintenance to stay safe, productive, and compliant with national standards.

In a sector where one cable failure can halt millions in production, prevention is not just better—it’s essential.