By TEBAOFLEX Jyen. Originally published on November 26, 2025.
Selecting an 8 kV, 15 kV or 25 kV Type SHD-GC mining cable requires separate checks of electrical rating, current-carrying capacity, voltage drop and mechanical duty. Increasing the supply voltage can reduce current for the same apparent power, but it does not automatically approve the insulation system, couplers, reel or protection arrangement.
Start with the applicable cable specification
ICEA lists ANSI/ICEA S-75-381 for portable and power feeder cables used in mines and similar applications. Specify the required edition and cable construction rather than assuming the type designation fixes every insulation thickness, conductor size or acceptance limit.
ICEA document catalogue — ANSI/ICEA S-75-381
Confirm system voltage, earthing arrangement, fault duration and equipment requirements with the responsible mine electrical designer. The cable, joints, connectors and terminations must all be suitable for the selected system. An existing lower-voltage reel installation may need mechanical and accessory changes when the cable diameter or mass increases.
What a manufacturer’s SHD-GC datasheet can establish
Southwire’s SPEC 47362 is an example of a specific 15 kV SHD-GC construction with flexible copper phase conductors, EPR insulation, individual copper/nylon braid shields, two grounding conductors and an insulated ground-check conductor. Its dimensional, bend and electrical data apply to the listed configurations, not automatically to TEBAOFLEX cables or every SHD-GC voltage class.
Southwire SPEC 47362 — construction-specific SHD-GC data
- Identify the exact voltage class, insulation level, conductor material and phase/ground/ground-check sizes.
- Obtain finished diameter tolerance and mass, not merely a nominal conductor cross-section.
- Request the permitted bending radius for installation and for the actual moving duty; distinguish radius from diameter.
- Verify allowable operating tension, reel layout, connectors and the method of transferring mechanical load.
Ampacity must match the installation
Record the conditions behind the stated ampacity: conductor temperature, ambient temperature, arrangement, shield bonding and duty. A free-air figure is not automatically the rating of cable left wound on a drum. Confirm the effect of reel geometry, layers, ventilation and remaining wound length using applicable manufacturer data or an agreed thermal assessment.
If a reference current is adjusted using correction factors, each factor needs a documented basis. A calculation such as I = Iref × Fambient × Freel is useful only when the inputs and their applicability are established. This guide does not assign universal 0.85, 0.65 or 0.45 multipliers to all mining reels.
Approximate three-phase voltage-drop method
For a balanced, sinusoidal three-phase load, an approximate line-to-line drop is ΔV ≈ √3 × I × L × (R cosφ + X sinφ). Use one-way cable length L in kilometres when the per-phase AC resistance R and reactance X are in Ω/km. Use resistance at the relevant conductor temperature and a consistent frequency. This simplified expression is not an exact transient motor-starting study.
Worked example — hypothetical inputs, not a cable rating
Assume 3,500 kVA, power factor 0.85, a 0.6 km run and per-phase AC resistance of 0.334 Ω/km. Assume reactances of 0.117, 0.127 and 0.135 Ω/km for three separate illustrative configurations. These assumed values are not certified product data or measurements from a mine.
- At 7.2 kV: I = 3,500 / (√3 × 7.2) = 280.66 A. Approximate drop = 100.78 V, or 1.400% of line voltage.
- At 13.8 kV: I = 146.43 A. Approximate drop = 53.38 V, or 0.387%.
- At 22.9 kV: I = 88.24 A. Approximate drop = 32.56 V, or 0.142%.
For the same apparent power, changing the example supply from 7.2 to 13.8 kV reduces current by approximately 47.8%. That arithmetic alone does not establish a permissible conductor size: ampacity, short-circuit withstand, starting behavior and equipment compatibility remain separate checks.
Motor starting can change both current and power factor, while source impedance also affects terminal voltage. Do not turn the steady-state percentages above into a guaranteed starting voltage by applying a fixed current multiplier. Acceptable voltage drop must come from the equipment and project requirements, not an assumed universal mine limit.
Do not confuse a feeder with a moving trailing cable
A published MP-GC feeder example uses Class B conductors and copper-tape screens and describes stationary horizontal distribution and permanent or semi-portable applications. Its manufacturer specifically requests consultation for vertical drops. Neither a feeder designation nor reduced diameter automatically qualifies a cable for repeated powered reeling, or for an unsupported shaft suspension.
Southwire SPEC 47821 — feeder application limitations
Agree acceptance evidence before supply
Request traceable dimensional, resistance and electrical test records for the ordered construction, plus mechanical qualification appropriate to its moving duty. Identify which checks are routine, sample or type tests. A list of test names is not proof that a delivered drum has passed.
IEC 60270 describes charge-based partial-discharge measurement. Cable-specific test voltage and acceptance criteria must be taken from the applicable product specification and agreed plan; a universal 5 pC limit is not inferred here from the measurement standard alone.
IEC 60270:2025 — partial-discharge measurement
Selection checklist
- Cable and accessory voltage/insulation ratings confirmed for the actual system.
- Ampacity assessed for the worst relevant reel and ambient condition.
- Voltage drop checked with consistent AC impedance, length and operating conditions.
- Reel, guides, allowable tension and terminations checked against the exact construction.
- Protection settings and acceptance records agreed with the responsible designer and supplier.
For a project-specific datasheet and an agreed inspection plan, contact TEBAOFLEX. WhatsApp: +86 185 9591 3361. Provide the equipment duty, cable route and applicable project specifications.