Three phase cores with composite individual screens, one unscreened pilot core and one unscreened earth core laid up around an elastomeric cradle and in contact with each other
What is Type 14 BS 6708 Trailing Cable?
Three phase cores with composite individual screens, one unscreened pilot core and one unscreened earth core laid up around an elastomeric cradle and in contact with each other
Turkish Translation: Kompozit bireysel ekranlı üç faz damarı ile ekransız bir kumanda ve bir toprak damarı elastomer fitil etrafında birbirlerine temas edecek şekilde bükülür.
Introduction to BS 6708 Type 14 Trailing Cable
The BS 6708 Type 14 Trailing Cable represents a specialized engineering solution within the British Standard family of mining cables, specifically designed for power distribution to excavating and crushing machines in underground coal mines and surface quarrying operations. This cable type features a unique configuration that balances electromagnetic protection with cost efficiency and simplified installation.
🔑 Critical Distinguishing Feature
Unlike Type 11 cables where all cores are screened, Type 14 features screened phase cores only, with the pilot core and earth core intentionally left unscreened. This design choice provides specific advantages in fault current handling and cable weight optimization while maintaining essential EMI protection for power conductors.
According to BS 6708:1998 classification, Type 14 belongs to the family of non-armoured cables with individually metallic screened cores rated at 640/1100 V, specifically designated for use with coalface cutters and similar mining machinery. The standard encompasses Types 7, 7M, 7S, 11, 14, and 16, each with distinct screening configurations optimized for specific operational requirements.
Configuration Summary:
- Phase Cores: 3 cores with composite tinned copper/nylon braided screens
- Pilot Core: 1 unscreened core for monitoring/control functions
- Earth Core: 1 unscreened core for fault current path
- Lay-up: All cores in contact around elastomeric cradle
As documented by the Tratos Group BS 6708 Standard Overview, Type 14 cables are engineered for environments where explosive gases and dust accumulate, requiring cables that minimize ignition risks while delivering substantial electrical power to heavy mining equipment.
Key Differences: Type 14 vs Type 11 Configuration
Screening Architecture Comparison
Understanding the screening differences between Type 14 and Type 11 is essential for proper cable selection in mining applications. These differences directly impact electromagnetic compatibility, fault current management, and installation complexity.
| Feature | Type 14 | Type 11 | Implication |
|---|---|---|---|
| Phase Core Screening | ✓ Screened (3 cores) | ✓ Screened (3 cores) | Both provide EMI protection for power conductors |
| Pilot Core Screening | ✗ Unscreened | ✓ Screened | Type 11 offers better monitoring signal protection |
| Earth Core | ✓ Dedicated unscreened core | Integrated with pilot screening | Type 14 has separate dedicated earth path |
| Core Configuration | 3×Phase + 2×Auxiliary | 3×Phase + 1×Pilot | Type 14 has additional earth core |
| Typical Sizes | 25-95 mm² phase | 16 mm² standard | Type 14 for higher power applications |
| Cable Weight | 3,550-9,800 kg/km | ~1,960 kg/km | Type 14 heavier due to larger conductors |
[SCREENED PHASE 1] ○ [SCREENED PHASE 2] ○ [SCREENED PHASE 3]
● ● ●
Cu/Nylon Braid Cu/Nylon Braid Cu/Nylon Braid
[UNSCREENED PILOT CORE] ◇ [UNSCREENED EARTH CORE]
NO SCREEN NO SCREEN
All cores laid up around ELASTOMERIC CRADLE
Advantages of Type 14 Unscreened Auxiliary Cores
Technical Benefits:
- Lower Fault Impedance: Unscreened earth core provides direct, low-impedance path for fault currents without screening resistance interference
- Reduced Cable Complexity: Simpler termination procedures for auxiliary cores without screen bonding requirements
- Cost Optimization: Lower material costs for larger cross-section applications (25-95 mm²)
- Enhanced Fault Current Capacity: Earth conductor sized independently for optimal fault current handling (up to 7,300 A for 1 second)
- Weight Efficiency: Marginal weight savings compared to fully screened configuration
When to Select Type 14 Over Type 11
Type 14 cables are the optimal choice for applications requiring:
- Higher power ratings (110A to 250A continuous current)
- Longer cable runs with larger conductor cross-sections
- Simplified earth continuity management
- Applications where pilot core EMI protection is less critical
- Systems with independent earth monitoring requirements
Purpose and Primary Applications
Core Operational Functions
BS 6708 Type 14 cables serve as critical power supply infrastructure for coalcutters and other machines operating in challenging mining environments. The cable’s configuration with three screened phase conductors plus unscreened pilot and earth cores provides optimized power delivery for high-demand applications.
Primary Equipment Applications
Heavy Excavating Machinery
Type 14 cables excel in powering continuous mining machines, roadheaders, and longwall shearers that require substantial electrical power (110-250A continuous) for their cutting heads and material handling systems. The larger conductor cross-sections (25-95 mm²) accommodate the high current demands of these power-intensive machines.
Crushing and Processing Equipment
Mobile crushing units operating in underground and surface mining environments require the robust power delivery capabilities of Type 14 cables. The heavy-duty chloroprene outer sheath withstands the abrasive conditions typical in crushing operations.
Environmental Deployment Zones:
- Deep Underground Mines: Explosive gas atmospheres (methane, coal dust)
- Surface Quarrying: Exposed to weather extremes and mechanical stress
- Hybrid Operations: Transitional zones between underground and surface facilities
Power Transmission Capabilities
According to research documented by Reeling Cable Technology Solutions, trailing cables serve as critical lifelines for mobile mining equipment, delivering electrical power while accommodating continuous movement. Type 14 cables specifically address the power density requirements of larger mining equipment through their optimized conductor sizing.
| Cable Size | Continuous Current @ 25°C | 1s Short Circuit Current | Typical Application |
|---|---|---|---|
| 3×25+2×16 mm² | 110 A | 3,450 A | Loading machines, auxiliary equipment |
| 3×35+2×16 mm² | 135 A | 3,450 A | Medium continuous miners |
| 3×50+2×25 mm² | 170 A | 4,550 A | Large continuous miners |
| 3×70+2×35 mm² | 205 A | 4,820 A | High-power roadheaders |
| 3×95+2×50 mm² | 250 A | 7,300 A | Heavy-duty longwall equipment |
Cable Construction and Material Structure
Seven-Layer Construction Architecture
BS 6708 Type 14 cables employ a sophisticated seven-layer construction system where each component is engineered to serve specific functions critical for mining environment performance.
| Layer | Material | Specification | Function |
|---|---|---|---|
| 1. Conductor | Electrolytic Tinned Copper | IEC 60228 Class 5 Stranded | Maximum conductivity with corrosion resistance and flexibility |
| 2. Insulation | EPR (Ethylene Propylene Rubber) | High dielectric strength compound | Electrical isolation with temperature stability (-40°C to +90°C) |
| 3. Separator | Colored Textile Tape | Core identification colors | Phase identification (Black, Grey, Brown; Blue pilot) |
| 4. Screen | Tinned Copper/Nylon Braid | Phase cores ONLY screened | EMI shielding for power conductors; pilot/earth unscreened |
| 5. Lay-up | Elastomeric Cradle Configuration | All cores in contact | Mechanical stability during flexing operations |
| 6. Bedding | Rubber-Based Compound | Cushioning filler material | Internal protection and shape maintenance |
| 7. Outer Sheath | Heavy-Duty Chloroprene (PCP) | Flame retardant elastomer | Environmental, mechanical, and chemical protection |
Conductor Technology: IEC 60228 Class 5 Compliance
The conductor system utilizes electrolytic copper processed through fine stranding to achieve IEC 60228 Class 5 flexibility ratings. According to international standards documentation, Class 5 conductors are specifically intended for flexible cables where repeated bending is required.
Stranding Configurations by Size:
| Cross Section (mm²) | Stranding | Wire Diameter (mm) | Nominal Conductor Diameter (mm) |
|---|---|---|---|
| 16 | 126/0.40 | 0.40 | 5.50 |
| 25 | 196/0.40 | 0.40 | 6.75 |
| 35 | 276/0.40 | 0.40 | 8.00 |
| 50 | 396/0.40 | 0.40 | 9.75 |
| 70 | 360/0.50 | 0.50 | 11.60 |
| 95 | 475/0.50 | 0.50 | 12.75 |
The tinning process applied to all copper conductors provides enhanced corrosion resistance critical for mining environments. According to EPR Cable Technology research, tinned conductors exhibit superior long-term performance in humid and chemically aggressive atmospheres typical of underground mining operations.
EPR Insulation System Properties
Ethylene Propylene Rubber (EPR) insulation provides exceptional electrical and mechanical properties essential for mining cable applications. According to Eland Cables technical documentation, EPR offers high dielectric strength with a wide thermal range typically from -55°C to 150°C.
Composite Screen Construction
The tinned copper/nylon braided screen over phase cores provides:
- Electromagnetic Interference Shielding: Prevents interference between power circuits and nearby control systems
- Fault Current Path: Additional parallel path for earth fault currents
- Mechanical Protection: Braided construction maintains flexibility while protecting insulation
Total Screen Cross Section by Cable Size:
- 3×25+2×16: 25.4 mm²
- 3×35+2×16: 25.4 mm²
- 3×50+2×25: 33.0 mm²
- 3×70+2×35: 35.0 mm²
- 3×95+2×50: 53.0 mm²
Heavy-Duty Chloroprene Outer Sheath
The outer sheath utilizes chloroprene (polychloroprene/neoprene) compound selected for its exceptional resistance properties in mining environments. The radial thickness increases with cable size to provide proportional protection:
| Cable Size | Outer Sheath Radial Thickness | Min Overall Diameter | Max Overall Diameter |
|---|---|---|---|
| 3×25+2×16 | 5.0 mm | 43.2 mm | 46.6 mm |
| 3×35+2×16 | 5.2 mm | 47.3 mm | 50.7 mm |
| 3×50+2×25 | 5.7 mm | 53.7 mm | 57.6 mm |
| 3×70+2×35 | 6.3 mm | 61.2 mm | 65.0 mm |
| 3×95+2×50 | 7.0 mm | 69.3 mm | 73.9 mm |
Complete Technical Specifications
Comprehensive Parameter Table – All Type 14 Configurations
The following detailed specifications cover all standard BS 6708 Type 14 cable sizes, providing essential engineering data for system design, cable selection, and installation planning.
| Parameter | 3×25+2×16 | 3×35+2×16 | 3×50+2×25 | 3×70+2×35 | 3×95+2×50 | Unit |
|---|---|---|---|---|---|---|
| Phase Conductor Data | ||||||
| Number × Cross Section | 3×25 | 3×35 | 3×50 | 3×70 | 3×95 | mm² |
| Stranding | 196/0.40 | 276/0.40 | 396/0.40 | 360/0.50 | 475/0.50 | wires/mm |
| Conductor Diameter | 6.75 | 8.00 | 9.75 | 11.60 | 12.75 | mm (nom) |
| Insulation Thickness | 1.6 | 1.6 | 1.7 | 1.8 | 2.0 | mm |
| Total Screen Cross Section | 25.4 | 25.4 | 33.0 | 35.0 | 53.0 | mm² |
| Earth Conductor (Unscreened) | ||||||
| Cross Section | 1×16 | 1×16 | 1×25 | 1×35 | 1×50 | mm² |
| Stranding | 126/0.40 | 126/0.40 | 196/0.40 | 276/0.40 | 396/0.40 | wires/mm |
| Conductor Diameter | 5.50 | 5.50 | 6.75 | 8.00 | 9.75 | mm (nom) |
| Insulation Thickness | 1.6 | 1.6 | 1.7 | 1.8 | 2.0 | mm |
| Pilot Conductor (Unscreened) | ||||||
| Cross Section | 1×25 | 1×35 | 1×50 | 1×70 | 1×95 | mm² |
| Stranding | 196/0.40 | 276/0.40 | 396/0.40 | 360/0.50 | 475/0.50 | wires/mm |
| Conductor Diameter | 6.75 | 8.00 | 9.75 | 11.60 | 12.75 | mm (nom) |
| Insulation Thickness | 1.5 | 1.5 | 1.6 | 1.6 | 1.7 | mm |
| Overall Cable Properties | ||||||
| Min Overall Diameter | 43.2 | 47.3 | 53.7 | 61.2 | 69.3 | mm |
| Max Overall Diameter | 46.6 | 50.7 | 57.6 | 65.0 | 73.9 | mm |
| Min Bending Radius | 420 | 457 | 519 | 585 | 666 | mm |
| Outer Sheath Radial Thickness | 5.0 | 5.2 | 5.7 | 6.3 | 7.0 | mm |
| Max Pulling Tension | 638 | 729 | 910 | 1,148 | 1,446 | kgf |
| Approximate Cable Weight | 3,550 | 4,280 | 5,650 | 7,520 | 9,800 | kg/km |
| Copper Weight | 1,307 | 1,675 | 2,340 | 3,228 | 4,326 | kg/km |
Electrical Performance Parameters
Current Carrying Capacity and Resistance Values
The electrical characteristics of BS 6708 Type 14 cables are optimized for high-power mining equipment operation, with careful attention to conductor resistance, current ratings, and fault current withstand capabilities.
| Electrical Parameter | 3×25+2×16 | 3×35+2×16 | 3×50+2×25 | 3×70+2×35 | 3×95+2×50 | Unit |
|---|---|---|---|---|---|---|
| Continuous Current Rating @ 25°C | 110 | 135 | 170 | 205 | 250 | A |
| Short Circuit Current (1 second) | 3,450 | 3,450 | 4,550 | 4,820 | 7,300 | A |
| Max DC Resistance @ 20°C (Phase/Earth) | 0.795 | 0.565 | 0.393 | 0.277 | 0.210 | Ω/km |
| Max DC Resistance @ 20°C (Pilot) | 1.240 | 1.240 | 0.795 | 0.565 | 0.393 | Ω/km |
| Screen Resistance (3 parallel) | 1.10 | 1.20 | 1.40 | 0.70 | 0.85 | Ω/km |
Short Circuit Current Analysis
The short circuit current ratings for Type 14 cables are calculated based on adiabatic heating assumptions according to IEC 60949 methodology. According to ScienceDirect Engineering research, ratings are typically assessed over one-second duration with conductor temperature not exceeding 250°C for EPR-insulated cables.
Short Circuit Calculation Formula:
I = k × S / √t
Where:
I = Short-circuit current (A)
k = Material constant for copper-EPR (typically 143 A·s0.5/mm²)
S = Conductor cross-sectional area (mm²)
t = Fault duration (seconds)
Example for 95mm² conductor:
I = 143 × 95 / √1 = 13,585 A theoretical
Actual rating: 7,300 A (conservative with safety factor)
Voltage Drop Considerations
For long cable runs typical in mining operations, voltage drop calculations are critical for system design. Using the resistance values provided:
Voltage Drop Calculation Example (3×95+2×50 at 250A, 100m):
Phase conductor resistance: 0.210 Ω/km
For 100m: 0.210 × 0.1 = 0.021 Ω
Three-phase voltage drop = √3 × I × R × cos(φ)
Assuming cos(φ) = 0.85:
ΔV = 1.732 × 250 × 0.021 × 0.85 = 7.73 V
Percentage of 640V phase voltage: 1.21% (Well within acceptable limits)
Earth Fault Current Path Analysis
Type 14’s unscreened earth core provides a direct, low-impedance path for earth fault currents. The combined earth path includes:
| Cable Size | Earth Core Resistance (Ω/km) | 3 Screens Parallel (Ω/km) | Combined Parallel Path (Ω/km) |
|---|---|---|---|
| 3×25+2×16 | 0.795 | 1.10 | 0.461 |
| 3×35+2×16 | 0.565 | 1.20 | 0.384 |
| 3×50+2×25 | 0.393 | 1.40 | 0.307 |
| 3×70+2×35 | 0.277 | 0.70 | 0.198 |
| 3×95+2×50 | 0.210 | 0.85 | 0.168 |
Compliance with International Standards
Primary Standard: BS 6708:1998
BS 6708 Type 14 cables comply with the British Standard BS 6708:1998 “Flexible cables for use at mines and quarries.” This comprehensive standard, classified under ICS 29.260.20 (Electrical apparatus for explosive atmospheres), establishes stringent requirements for cable construction, testing, and performance in hazardous mining environments.
BS 6708 Type 14 Classification:
- Category: Non-armoured cables with individually metallic screened cores
- Rated Voltage: 640/1100 V
- Test Voltage: 3 kV AC
- Application Group: Coalface cutters and similar machines
- Screening Configuration: Phase cores screened; pilot and earth cores unscreened
Referenced Standards and Specifications
| Standard | Title/Scope | Application to Type 14 |
|---|---|---|
| IEC 60228 | Conductors of insulated cables | Class 5 flexible conductor requirements |
| IEC 60724 | Short-circuit temperature limits | 250°C max for EPR insulated cables |
| IEC 60949 | Short-circuit current ratings | Adiabatic calculation methodology |
| BS 7655-1.2 | 90°C application elastomeric compounds | EPR insulation material specifications |
| BS 7655-2.3 | Sheathing compounds | Chloroprene outer sheath requirements |
| EN/IEC 60332-1-2 | Flame retardance testing | Single vertical flame propagation test |
| BCS 188:1978 | British Coal Specification | Historical reference for trailing cables |
Quality Assurance Testing Regime
Type 14 cables undergo comprehensive factory testing to verify compliance with BS 6708 requirements:
Certifications and Approvals
BS 6708 Type 14 cables may carry additional certifications depending on deployment region:
- ATEX Directive 2014/34/EU: For European explosive atmosphere applications
- MSHA (USA): Mine Safety and Health Administration approval
- MA (China): Coal mine safety certification
- SANS 1520: South African mining cable standards
Comparison: BS 6708 Type 14 vs VDE 0250 Part 812
Standards Overview
Both British Standard BS 6708 and German Standard DIN VDE 0250 represent internationally recognized frameworks for mining and industrial flexible cable specifications. DIN VDE 0250 Part 812 specifically governs EPR insulated flexible cables designated NSSHÖU, while BS 6708 Type 14 addresses mining trailing cables with specific screening configurations.
According to Eland Cables VDE expertise, Germany is the only country to have issued special design regulations for flexible electrical cables covering cranes and material handling equipment, making DIN VDE 0250 globally recognized as the ultimate standard for tough rubber sheathed flexible cables.
| Parameter | BS 6708 Type 14 | VDE 0250-812 (NSSHÖU) | Technical Analysis |
|---|---|---|---|
| Rated Voltage | 640/1100 V | 450/750 V | BS 6708 superior for HV mining equipment |
| Test Voltage | 3 kV | 2.5 kV typical | BS 6708 higher safety margin |
| Primary Application | Underground coal mining with explosive atmospheres | General industrial, tunneling, mining | Type 14 more specialized |
| Conductor Class | IEC 60228 Class 5 | DIN EN 60228 / VDE 0295 Class 5 | Equivalent flexibility |
| Insulation Material | EPR | EPR or equivalent elastomer | Same base material |
| Screening Configuration | Phase cores only (Pilot/Earth unscreened) | Various options (screened/unscreened) | Type 14 optimized earth path |
| Dedicated Earth Core | Yes (separate unscreened) | Configuration dependent | Type 14 better fault current management |
| Outer Sheath | Heavy-duty chloroprene (PCP) | Polychloroprene or equivalent | Comparable protection |
| Temperature Range | -40°C to +85°C ambient | -25°C to +60°C flexible use | Type 14 wider range for deep mines |
| Short Circuit Temperature | 250°C (1 second) | 250°C (short circuit) | Equivalent thermal performance |
| Current Ratings (Example) | 110-250 A (25-95mm²) | Variable by configuration | Type 14 higher power density |
| Explosive Atmosphere Design | Specifically for gassy mines | General hazardous areas | Type 14 methane-specific |
Key Advantages of BS 6708 Type 14
Technical Superiorities:
- Higher voltage rating (640/1100 V) accommodates larger mining equipment power demands
- Dedicated unscreened earth core provides optimized low-impedance fault current path
- Separate pilot core allows independent monitoring and control functions
- Phase-only screening balances EMI protection with simplified termination
- Extended temperature range (-40°C) suits deep underground applications
- Higher short circuit ratings (up to 7,300 A) for robust protection coordination
VDE 0250-812 Strengths:
- Global recognition as ultimate standard for tough rubber sheathed cables
- Broader application flexibility across industrial sectors
- Established European certification network
- Extensive product variants (NSSHÖU, NSHTÖU, etc.)
- Lower voltage rating may suit some applications with cost benefits
Selection Decision Matrix
| Application Requirement | Recommended Choice | Technical Justification |
|---|---|---|
| Underground coal mining (methane risk) | BS 6708 Type 14 | Specific explosive atmosphere design |
| High-power equipment (>100A continuous) | BS 6708 Type 14 | Higher voltage and current ratings |
| Simplified earth continuity management | BS 6708 Type 14 | Dedicated unscreened earth core |
| General industrial heavy-duty applications | VDE 0250-812 | Broader equipment compatibility |
| Lower voltage systems (<750V) | VDE 0250-812 | Cost optimization |
| Deep mines with extreme temperatures | BS 6708 Type 14 | Superior low-temperature flexibility |
Safety Thresholds and Operational Precautions
Critical Temperature Limits
⚠️ Maximum Temperature Thresholds:
- Maximum Conductor Temperature (Continuous): 90°C
- Short Circuit Temperature (1 second max): 250°C
- Ambient Temperature Range: -40°C to +85°C
- Installation Temperature Minimum: -20°C (to prevent sheath cracking)
Warning: Exceeding temperature limits causes irreversible damage to EPR insulation and chloroprene sheath, potentially leading to electrical failure and fire hazards in explosive atmospheres.
Mechanical Safety Parameters
| Safety Parameter | Threshold Value | Consequences of Exceeding |
|---|---|---|
| Minimum Bending Radius | Approx. 9×D (varies by size) | Internal conductor stress, insulation cracking |
| Maximum Pulling Tension (95mm²) | 1,446 kgf | Conductor elongation, strand breakage |
| Permanent Tensile Force | 15 N/mm² | Permanent cable deformation |
| Outer Sheath Integrity | No breaches | Moisture ingress, chemical attack on insulation |
Explosive Atmosphere Safety Considerations
According to Amplex Mining Cable Guide, explosion-proof characteristics are essential in underground coal mining where methane gas or coal dust can create explosive atmospheres. Type 14 cables incorporate specific safety features:
Intrinsic Safety Features:
- Heavy-duty chloroprene sheath: Flame retardant, self-extinguishing (EN/IEC 60332-1-2 compliant)
- EPR insulation: High dielectric strength prevents electrical tracking
- Composite screening: Minimizes spark generation from electromagnetic interference
- Tinned copper conductors: Corrosion-resistant connections reduce high-resistance faults
- Robust earthing: Dedicated earth core ensures rapid fault clearance
Installation Safety Requirements
Pre-Installation Safety Checklist:
- Verify cable voltage rating matches system requirements (640/1100 V)
- Confirm conductor cross-section adequate for maximum load current
- Check ambient temperature within -40°C to +85°C range
- Ensure cable routing maintains minimum bending radius throughout
- Verify earth continuity path integrity (earth core + screens)
- Test insulation resistance (>100 MΩ·km at 20°C)
- Conduct voltage withstand test (3 kV AC for 5 minutes)
- Verify protective device settings match cable fault ratings
- Confirm cable terminations use approved explosion-proof glands
- Document all test results for compliance records
Operational Monitoring Requirements
Continuous operational monitoring ensures safe cable performance throughout service life:
| Monitoring Parameter | Frequency | Acceptance Criteria | Action if Failed |
|---|---|---|---|
| Visual Sheath Inspection | Weekly | No cuts, abrasions, or swelling | Repair or replace damaged sections |
| Insulation Resistance | Monthly | >1 MΩ per circuit | Investigate moisture ingress |
| Earth Core Continuity | Monthly | <1 Ω end-to-end | Check terminations and connections |
| Screen Resistance | Quarterly | Within 10% of rated value | Verify screen bonding integrity |
| Conductor Temperature | Continuous (if possible) | <90°C | Reduce load or improve cooling |
| High Voltage Test | Annually | Pass 3 kV for 5 minutes | Replace cable section |
Fault Current Protection Coordination
Protective device settings must coordinate with Type 14 cable fault current ratings to ensure rapid fault clearance while preventing nuisance tripping:
Protection Coordination Example (3×95+2×50):
Cable 1-second short circuit rating: 7,300 A
Recommended protective device settings:
– Instantaneous trip: Maximum 5,840 A (80% of cable rating)
– Time-delayed trip: Adjust I²t characteristic to protect cable
– Ground fault: Set to detect faults >10A through earth core
– Earth continuity monitor: Alarm if earth resistance exceeds 1 Ω
Common Problems and Troubleshooting Solutions
Mechanical Failure Modes
Problem 1: Outer Sheath Abrasion and Damage
Symptoms: Visible wear patterns, cuts, exposed internal layers, localized swelling.
Root Causes:
- Dragging over sharp rock surfaces without cable protection
- Inadequate cable handler/chain configuration
- Exceeding minimum bending radius during operation
- Chemical attack from hydraulic fluid spills
Solutions:
- Install appropriate cable protection chains rated for mining applications
- Route cables away from identified abrasion hazards
- Apply removable protective sleeves at high-wear locations
- Clean oil/chemical contamination promptly
- Implement regular inspection schedule (weekly visual checks)
Problem 2: Conductor Fatigue and High-Resistance Faults
Symptoms: Intermittent power loss, unexplained voltage drops, localized heating, insulation discoloration.
Root Causes:
- Repeated flexing below minimum bending radius
- Excessive tensile forces during equipment operation
- Torsional stress from improper cable lay-up
- Work hardening of copper strands
Solutions:
- Redesign cable routing to maintain minimum bending radius (420-666mm depending on size)
- Install tension control devices to limit forces below maximum pulling tension
- Monitor cable flex cycles and replace before fatigue failure
- Use thermal imaging to identify hot spots indicating high-resistance connections
Electrical Performance Degradation
Problem 3: Declining Insulation Resistance
Symptoms: Megohmmeter readings below acceptable levels, increased leakage current, ground fault alarms.
Root Causes:
- Moisture ingress through damaged outer sheath
- Water tree development in EPR insulation
- Thermal aging from sustained overtemperature operation
- Chemical contamination penetrating insulation
Solutions:
- Repair or replace damaged sheath sections immediately
- Ensure operation below 90°C conductor temperature
- Monthly insulation resistance testing (>1 MΩ minimum)
- Keep cable away from standing water and chemical sources
- Consider replacing cables showing consistent IR decline trends
Problem 4: Earth Continuity Issues
Symptoms: Earth fault protection fails to operate correctly, elevated touch potentials, ground fault indication without clearing.
Root Causes:
- Broken or high-resistance earth conductor connections
- Corrosion at earth core terminations
- Mechanical damage to unscreened earth core
- Improper screen bonding connections
Solutions:
- Monthly earth continuity testing (<1 Ω end-to-end)
- Clean and re-establish earth termination connections
- Verify screen bonding at both ends of cable
- Replace cables with damaged earth core sections
- Ensure terminations use anti-corrosion compounds
Screen-Specific Issues
Problem 5: Phase Core Screen Degradation
Symptoms: Increased electromagnetic interference, fault current protection issues, heating at screen connections.
Root Causes:
- Mechanical damage to tinned copper/nylon braid
- High-resistance screen terminations
- Corrosion at screen bonding points
- Improper gland installation not maintaining 360° contact
Solutions:
- Quarterly screen resistance measurement (should match table values ±10%)
- Use proper cable glands maintaining complete screen contact
- Apply anti-oxidant compound to screen connections
- Verify screen parallel resistance calculation matches expected values
Environmental Challenges
Problem 6: Cold Temperature Performance Issues
Symptoms: Cable becomes stiff and brittle, outer sheath cracking, reduced flexibility.
Root Causes:
- Installation or operation below -20°C for flexible applications
- Storage in unheated areas during winter
- Rapid temperature cycling causing material stress
Solutions:
- Pre-warm cables to above -10°C before installation in cold environments
- Increase bending radius allowances in cold temperature operations
- Specify enhanced cold-grade chloroprene for extreme applications
- Store cables in temperature-controlled environments
Preventive Maintenance Schedule
| Maintenance Activity | Frequency | Parameters to Check | Pass Criteria |
|---|---|---|---|
| Visual Inspection | Weekly | Sheath damage, abrasion, cuts | No visible damage |
| Insulation Resistance Test | Monthly | Megohmmeter at 1000V DC | >1 MΩ per circuit |
| Earth Continuity Test | Monthly | Low-resistance ohmmeter | <1 Ω end-to-end |
| Phase Conductor Resistance | Quarterly | DC resistance at 20°C | Within specified values |
| Screen Resistance | Quarterly | 3 screens parallel resistance | Within ±10% of rated |
| Termination Inspection | Quarterly | Temperature rise, corrosion, tightness | No heating, clean contacts |
| High Voltage Withstand Test | Annually | 3 kV AC for 5 minutes | No breakdown |
Contact Anhui Feichun Special Cable Co., Ltd.
Expert Technical Support for BS 6708 Type 14 Trailing Cables
Our specialized engineering team provides comprehensive technical consultation for Type 14 mining cable applications, including custom configurations, installation guidance, fault analysis, and performance optimization for high-power mining equipment.
[email protected]
[email protected]
+86 138 5512 3218
Why Choose Feichun for Type 14 Cables?
- ISO 9001:2015 Certified Manufacturing
- Full BS 6708 Compliance Testing
- IEC 60228 Class 5 Conductor Production
- Custom Cross-Section Configurations (25-95mm²)
- Global Export Experience to Mining Operations
- Complete Technical Documentation Package
- Factory Test Certificates Provided
Request Technical Data Package
Contact our engineering team for comprehensive technical data sheets including:
- Detailed dimensional drawings for all Type 14 configurations
- Factory test certificates (voltage withstand, insulation resistance)
- Material certification documents (EPR compound, chloroprene sheath)
- Installation and termination guidelines
- Short circuit coordination calculations
- Custom length and configuration quotations
References and Further Reading
- British Standards Institution. (1998). BS 6708:1998 – Flexible cables for use at mines and quarries. BSI Group.
- International Electrotechnical Commission. (2004). IEC 60228 – Conductors of insulated cables. IEC.
- International Electrotechnical Commission. (1988). IEC 60949 – Calculation of thermally permissible short-circuit currents. IEC.
- Amplex Mining Solutions. (2025). BS 6708 Type 321 Mining Cable Technical Guide. Retrieved from amplexmining.com.au
- Reeling Cable Technology. (2025). Coal Cutter Cables for Underground Mining Applications. Retrieved from reelingcable.com
- Tratos Group. (2023). BS 6708 Standard Specifications. Retrieved from tratosgroup.com
- VDE Publishing House. (1985). DIN VDE 0250-812 – Rubber insulated flexible cable NSSHÖU. VDE.
- Eland Cables. (2024). VDE 0250 Standard Cables – Global Recognition. Retrieved from elandcables.com
- MSHA Technical Support. (2023). Short-Circuit Calculations for Mining Power Systems. Retrieved from msha.gov
- EPR Cable Technology Consortium. (2017). Ethylene Propylene Rubber Cable Properties. Retrieved from eprcable.ims.uconn.edu
