Application & Operating Conditions
BS 6708 Type 44 is a 125/72 V flexible trailing cable built specifically to power handheld rotary percussive coal and rock drilling machines from flameproof drill transformer panels in deep underground mines where firedamp and combustible dust can accumulate, as well as rugged surface quarry drilling sites.
125 V Underground Drill Panels
Matched to standard British mining 125 V phase-to-phase (72 V phase-to-earth) step-down drill gate-end transformers with restricted earth-fault and pilot-loop interlock protection.
Composite Copper/Nylon Phase Screens
Each 6 mm² phase core is enclosed in a flexible tinned-copper and nylon composite braid (11 Ω/km for 3 screens in parallel) that withstands sharp manual kinking without wire breakage.
High Manual Handling Durability
Combines ultra-supple 84/0.30 mm stranding, a cushioned central elastomeric cradle, rubber inner bedding, and a 3.0 mm PCP jacket rated for 218 kgf pulling tension along rough face floors.
Type 44 vs Type 43 Selection Tip: Choose BS 6708 Type 44 when your mine safety standard requires metallic composite copper/nylon braided phase screens (11 Ω/km parallel screen path). Choose BS 6708 Type 43 when a metal-braid-free semiconducting elastomeric screen system is preferred to eliminate broken screen wires under extreme torsional twisting.
Cable Construction (BS 6708 Type 44 Screened Drill Architecture)
Constructed strictly to BS 6708 Type 44: three individually composite-screened 6 mm² phase cores, one unscreened 6 mm² pilot core, and one unscreened 6 mm² earth core laid up in contact around a profiled elastomeric cradle.
| Layer / Component | Material & BS 6708 Engineering Specification |
|---|---|
| 1. Conductors (5 × 6 mm²) | Electrolytic flexible stranded tinned copper wire, IEC 60228 Class 5 (84/0.30 mm stranding, 3.30 mm conductor diameter) across all phase, earth, and pilot cores. |
| 2. Core Insulation | Ethylene Propylene Rubber (EPR) compound, 1.00 mm nominal radial wall thickness. |
| 3. Core Identification Separator | Coloured textile tape over the EPR insulation for clear visual distinction of the three phase cores, pilot core, and earth core. |
| 4. Phase Screens (3 Cores) | Composite tinned copper wire and nylon yarn braided screen applied individually over the three phase cores (total metallic screen cross-section 11 mm²); pilot and earth cores remain unscreened. |
| 5. Cradle & Core Lay-Up | All five cores laid up in contact with each other around a central elastomeric rubber cradle for crush resistance and torsional balance. |
| 6. Inner Bedding & Outer Sheath | Extruded rubber-based inner bedding compound followed by a heavy-duty black chloroprene (PCP) outer sheath (3.0 mm nominal radial thickness). |
BS 6708 Type 44 Cross-Section: Three composite copper/nylon screened phase cores plus one unscreened pilot core and one unscreened earth core laid around a central elastomeric cradle inside rubber bedding and a 3.0 mm black PCP sheath.
Technical Characteristics
Complete electrical, short-circuit, and mechanical ratings verified to British Standard BS 6708 Type 44 (125/72 V).
| Parameter | BS 6708 Rated Value |
|---|---|
| Reference Standard | BS 6708 (Type 44 Flexible Trailing Cable for Handheld Drilling Machines) |
| Rated Voltage (U / Uo) | 125 / 72 V AC (3-Phase 125 V System with 72 V Neutral-Earth Point) |
| Routine AC Test Voltage | 1.5 kV AC |
| Nominal Cross-Section | 5×6 mm² (3×6 mm² Screened Phases + 1×6 mm² Earth + 1×6 mm² Pilot) |
| Continuous Current & 1 s Short-Circuit | 46 A Continuous (@ 25 °C Ambient) | 908 A for 1 Second |
| Minimum Bending Radius | 241 mm |
| Maximum Pulling Tension | 218 kgf |
| Max. DC Resistance (@ 20 °C) | Phase & Earth: 3.48 Ω/km | Pilot: 3.48 Ω/km | 3 Screens in Parallel: 11 Ω/km |
BS 6708 Type 44 Specification & Electrical Data Table
Nominal dimensional, mechanical, current, short-circuit, and DC resistance data for BS 6708 Type 44 (5×6 mm²).
1. Core, Screen & Overall Cable Dimensions (5×6 mm²)
| Nominal Size (mm²) | Phase / Earth / Pilot (mm²) | Stranding (No./mm) | Cond. Dia. (mm) | Insul. Thick. (mm) | Total Screen Area (mm²) | Outer Sheath (mm) | Min. OD (mm) | Max. OD (mm) | Min. Bend Radius (mm) | Max. Pull (kgf) | Approx. Weight (kg/km) | Copper Weight (kg/km) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 5×6 | 3×6 / 1×6 / 1×6 | 84/0.30 | 3.30 | 1.00 | 11 | 3.0 | 24.7 | 26.7 | 241 | 218 | 1150 | 400 |
2. Current Ratings, Short-Circuit Capacity & DC Resistance
| Nominal Size (mm²) | Continuous Current @ 25 °C (A) | 1 s Short-Circuit Current (A) | Phase & Earth Max. DC Res. @ 20 °C (Ω/km) | Pilot Max. DC Res. @ 20 °C (Ω/km) | 3 Screens in Parallel Max. DC Res. @ 20 °C (Ω/km) |
|---|---|---|---|---|---|
| 5×6 | 46 | 908 | 3.48 | 3.48 | 11 |
Selection Guide: BS 6708 Drill, Catenary & Auxiliary Mining Cables
Compare BS 6708 Type 44 against Type 43 conducting-rubber drill cable and related BS 6708 auxiliary cables.
| BS 6708 Model | Core & Pilot Architecture, Earth Design & Primary Duty |
|---|---|
| BS 6708 Type FS4 (640/1100V Flat) | BS 6708 Type FS4 (640/1100V Flat): Flat parallel 4-core geometry (4×2.5 & 4×4 mm²) with tinned copper braided screens on all phase and pilot cores for monorail festoon and overhead catenary loops (100–120 mm bend radius). |
| BS 6708 Type 44 (125/72V Screened Drill) (This Product) | 5×6 mm² handheld drilling machine cable with composite copper/nylon braided screens on 3 phase cores + unscreened pilot & earth cores around an elastomeric cradle. |
| BS 6708 Type 43 (125/72V Conducting Rubber Drill) | BS 6708 Type 43 (125/72V Conducting Rubber Drill): 5×6 mm² metal-braid-free drilling cable with cores separated around a semiconducting elastomeric cradle and 1.5 mm conducting rubber inner sheath for non-fraying flex fatigue resistance. |
| BS 6708 Type 70 & Type 71 (320/550V Armoured) | BS 6708 Type 70 & Type 71 (320/550V Armoured): 4-core (Type 70, 4×4 mm²) and 5-core (Type 71, 5×4 mm²) unscreened EPR power & coalface lighting cables protected by 7/0.45 mm galvanized steel pliable wire armour. |
| BS 6708 Type 506 / 512 / 518 / 524 (320/550V Control) | BS 6708 Type 506 / 512 / 518 / 524 (320/550V Control): 6-, 12-, 18-core (1.34 mm²) and 24-core (0.93 mm²) individually composite-screened & pliable wire armoured control cables for inter-segment mining machine telemetry and pilot interlocks. |
| BS 6708 Type 7 (640/1100V Trailing) | BS 6708 Type 7 (640/1100V Trailing): Primary 640/1100 V unarmoured coalcutter trailing feeder (16–150 mm²) with 3 composite-screened phase cores, 1 unscreened pilot core, and central bare earth. |
Frequently Asked Questions (FAQ)
Technical questions regarding BS 6708 Type 44 voltage designation, composite nylon/copper screens, and coupler compatibility.
Why is BS 6708 Type 44 rated at 125/72 V instead of 640/1100 V?
Underground handheld coal and rock drills are operated directly by miners in wet, confined roadways. British coal mining electrical regulations mandate step-down 125 V phase-to-phase supply transformers with a earthed star point limiting phase-to-earth fault potential to 72 V, paired with BS 6708 Type 44 or Type 43 5×6 mm² trailing cables.
Why does Type 44 combine tinned copper wire with nylon yarn in its phase screens?
Handheld drill cables undergo constant manual coiling, dragging, and whip flexing right behind the drill chuck. Interweaving resilient nylon yarn with tinned copper strands prevents metallic braid work-hardening and broken wire splinters that could puncture the 1.00 mm EPR core insulation.
Are the pilot and earth cores screened in BS 6708 Type 44?
No. Only the three 125 V phase cores carry composite tinned-copper/nylon braided screens (11 mm² combined screen area). Both the 6 mm² earth core and 6 mm² intrinsically safe pilot interlock core are unscreened and laid in contact with the phase screens around the central elastomeric cradle.
Order BS 6708 Type 44 Handheld Mining Drill Cable
Request factory pricing for BS 6708 Type 44 (5×6 mm²) in bulk drums or cut-to-length face drill leads with full 1.5 kV AC dielectric test reports.
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