Application & Operating Conditions
BS 6708 Type 630 and Type 631 are 3.8/6.6 kV individually phase-screened, pliable wire armoured (PWA) flexible power cables engineered for main underground roadway transformers, high-capacity crushing and excavating plant, and semi-mobile surface quarry substations operating in explosive gas and coal-dust atmospheres.
Screened 6.6 kV Fault Containment
Combines a 5.0 mm medium-voltage EPR wall with individual composite copper/nylon braided phase screens so any insulation degradation trips earth-leakage protection before phase-to-phase arcing can occur.
Type 630 (3C) vs Type 631 (3C + Earth)
Type 630 (3×35 to 3×150 mm²) utilizes contacting phase screens plus pliable steel armour for earth return; Type 631 (3×50+35 & 3×70+50 mm²) adds a dedicated unscreened 5.0 mm EPR internal earth core.
Heavy 7/0.90 & 7/1.25 mm Pliable Armour
Multi-wire galvanized steel strand armour delivers crush resistance against roof falls while preserving semi-mobile handling flexibility (12 × Max. OD minimum bend radius).
6.6 kV Armoured Comparison: Choose BS 6708 Type 630 / Type 631 when individual metallic/nylon phase screens are required inside pliable steel armour. For 4-core (3 phases + 1 pilot) unscreened 6.6 kV pliable wire armoured feeders, view BS 6708 Type 621; for unarmoured flexible 6.6 kV machine trailing cables, view BS 6708 Type 730.
Cable Construction (BS 6708 Type 630 & Type 631)
Constructed strictly to BS 6708 with 5.0 mm EPR dielectric, composite copper/nylon phase screens, thick rubber bedding, galvanized steel pliable wire armour, and a heavy-duty black PCP outer sheath.
| Layer / Component | Material & BS 6708 Engineering Specification |
|---|---|
| 1. Conductors | Electrolytic flexible stranded tinned copper wire, IEC 60228 Class 5 (35 mm² to 150 mm² phase conductors; 35 mm² and 50 mm² earth conductors in Type 631). |
| 2. Medium-Voltage Insulation | High-grade Ethylene Propylene Rubber (EPR) extruded to 5.0 mm nominal radial thickness on all phase cores (and on the Type 631 earth core). |
| 3. Phase Core Screens | Composite tinned copper wire and nylon braided screen applied over each of the three phase cores; the fourth earth core in Type 631 is unscreened. |
| 4. Core Lay-Up | Three screened phase cores (Type 630) or three screened phase cores plus one unscreened earth core (Type 631) laid up in contact with each other. |
| 5. Inner Sheath / Bedding | Extruded rubber-based inner bedding compound, 3.8 mm radial thickness (3×35 & 3×50) or 5.0 mm radial thickness (all larger sizes and Type 631). |
| 6. Pliable Wire Armour (PWA) | Helical galvanized steel pliable wire strand armour (7/0.90 mm or 7/1.25 mm) with low DC resistance (0.39–0.76 Ω/km at 20 °C). |
| 7. Outer Sheath | Heavy-duty black chloroprene (PCP) outer sheath (6.0 mm to 8.0 mm radial thickness), resistant to abrasion, oils, mine water, and flame spread. |
BS 6708 Type 630 / 631 Cross-Section (Type 630 Shown): Three 5.0 mm EPR medium-voltage phase cores individually screened with composite copper/nylon braid inside thick rubber bedding, galvanized steel pliable wire armour, and a black PCP outer sheath.
Technical Characteristics
Electrical, 15 kV dielectric test, dimensional, and parallel resistance parameters verified to BS 6708 Type 630 and Type 631.
| Parameter | BS 6708 Rated Value |
|---|---|
| Reference Standard | BS 6708 (Type 630 & Type 631 3.8/6.6 kV Screened Pliable Wire Armoured Cables) |
| Rated Voltage (Uo/U) | 3.8 / 6.6 kV AC (3800 / 6600 V) |
| Routine AC Test Voltage | 15 kV AC |
| Configurations | Type 630: 3×35 to 3×150 mm² (6 Sizes) | Type 631: 3×50+35 & 3×70+50 mm² (2 Sizes) |
| Dielectric Wall Thickness | 5.0 mm EPR across all phase and Type 631 earth cores |
| Minimum Bending Radius | 894 mm (3×35 mm²) to 1247 mm (3×150 mm²) (12 × Max. OD) |
| Continuous Current Rating (@ 25 °C) | 135 A (35 mm²) up to 320 A (150 mm²) |
| Armour & Parallel Screen Resistance | Armour: 0.39–0.76 Ω/km | 3 Screens in Parallel: 0.10–0.88 Ω/km (@ 20 °C) |
BS 6708 Type 630 & Type 631 Complete Specification Tables (8 Sizes)
Complete core, sheath, pliable armour, diameter, bend radius, weight, current, and DC resistance specifications for Type 630 and Type 631.
1. Core, Sheath, Pliable Armour & Overall Cable Dimensions (Type 630 & Type 631)
| BS 6708 Type | Nominal Size (mm²) | Phase Strand (Dia. mm) | Phase Insul. (mm) | Earth CSA & Strand | Inner Sheath (mm) | Inner Dia. Min–Max (mm) | Armour Size (No./mm) | Outer Sheath (mm) | Min. OD (mm) | Max. OD (mm) | Min. Bend Radius (mm) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Type 630 | 3×35 | 276/0.40 (8.40) | 5.0 | — | 3.8 | 53.1 – 56.1 | 7/0.90 | 6.0 | 70.5 | 74.5 | 894 |
| Type 630 | 3×50 | 396/0.40 (10.10) | 5.0 | — | 3.8 | 56.0 – 60.0 | 7/0.90 | 6.3 | 75.0 | 79.3 | 952 |
| Type 630 | 3×70 | 360/0.50 (11.90) | 5.0 | — | 5.0 | 63.0 – 67.0 | 7/1.25 | 6.8 | 80.6 | 84.9 | 1019 |
| Type 630 | 3×95 | 475/0.50 (13.90) | 5.0 | — | 5.0 | 72.3 | 7/1.25 | 7.3 | 90.6 | 94.9 | 1139 |
| Type 630 | 3×120 | 608/0.50 (15.50) | 5.0 | — | 5.0 | 75.5 | 7/1.25 | 7.6 | 94.4 | 98.7 | 1185 |
| Type 630 | 3×150 | 756/0.50 (17.20) | 5.0 | — | 5.0 | 80.0 | 7/1.25 | 8.0 | 99.6 | 103.9 | 1247 |
| Type 631 | 3×50+35 | 396/0.40 (10.10) | 5.0 | 1×35 (276/0.40) | 5.0 | 65.4 – 69.2 | 7/0.90 | 6.9 | 86.7 | 91.0 | 1092 |
| Type 631 | 3×70+50 | 360/0.50 (11.90) | 5.0 | 1×50 (396/0.40) | 5.0 | 70.5 – 74.3 | 7/1.25 | 7.4 | 92.8 | 97.1 | 1166 |
2. Weights, Current Ratings & Phase / Earth / Armour / Screen DC Resistance
| BS 6708 Type | Nominal Size (mm²) | Approx. Weight (kg/km) | Copper Weight (kg/km) | Current @ 25 °C (A) | Phase Cond. DC Res. (Ω/km) | Earth Cond. DC Res. (Ω/km) | Armour DC Res. (Ω/km) | 3 Screens Parallel (Ω/km) |
|---|---|---|---|---|---|---|---|---|
| Type 630 | 3×35 | 8400 | 1010 | 135 | 0.565 | — | 0.76 | 0.10 |
| Type 630 | 3×50 | 9850 | 1450 | 170 | 0.393 | — | 0.71 | 0.88 |
| Type 630 | 3×70 | 12050 | 2020 | 205 | 0.277 | — | 0.46 | 0.72 |
| Type 630 | 3×95 | 13850 | 2750 | 250 | 0.210 | — | 0.43 | 0.78 |
| Type 630 | 3×120 | 19200 | 3460 | 295 | 0.164 | — | 0.41 | 0.62 |
| Type 630 | 3×150 | 21200 | 4330 | 320 | 0.132 | — | 0.39 | 0.67 |
| Type 631 | 3×50+35 | 12100 | 2100 | 170 | 0.393 | 0.565 | 0.45 | 0.45 |
| Type 631 | 3×70+50 | 14250 | 3100 | 205 | 0.277 | 0.393 | 0.42 | 0.42 |
Selection Guide: BS 6708 Medium-Voltage Mining Cables (3.3 kV & 6.6 kV)
Compare BS 6708 Type 630 & Type 631 (3.8/6.6 kV screened armoured) with Type 621 (6.6 kV unscreened armoured), Type 730 (6.6 kV unarmoured trailing), and 3.3 kV feeders.
| BS 6708 Model | Core & Pilot Architecture, Earth Design & Primary Duty |
|---|---|
| BS 6708 Type 307 / 307M / 307S (1.9/3.3kV Coalcutter Trailing) | BS 6708 Type 307 / 307M / 307S (1.9/3.3kV Coalcutter Trailing): Unarmoured 1900/3300 V flexible coalcutter trailing cables (25–150 mm², 17 sizes) with 3 composite-screened EPR phases, central bare earth, and single (307), screened (307M), or 3-core (307S) pilot options. |
| BS 6708 Type 321 & Type 331 (1.9/3.3kV Blue-Stripe Armoured) | BS 6708 Type 321 & Type 331 (1.9/3.3kV Blue-Stripe Armoured): BS 6708:1998 1900/3300 V pliable wire armoured roadway extension & quarry trailing cables (25–150 mm²) with blue-striped black PCP sheath. |
| BS 6708 Type 621 (3.8/6.6kV Unscreened Armoured) | BS 6708 Type 621 (3.8/6.6kV Unscreened Armoured): 3800/6600 V pliable wire armoured 4-core (3 phases + 1 pilot, 4×35–4×150 mm²) unscreened 5.0 mm EPR power feeder. |
| BS 6708 Type 630 & Type 631 (3.8/6.6kV Screened Armoured) (This Product) | 3.8/6.6 kV individually composite-screened pliable wire armoured mining power cables (Type 630 3-core 35–150 mm²; Type 631 3+Earth 50–70 mm²). |
| BS 6708 Type 730 (3.8/6.6kV Unarmoured Screened Trailing) | BS 6708 Type 730 (3.8/6.6kV Unarmoured Screened Trailing): Unarmoured 3800/6600 V flexible screened trailing cable (3×35 to 3×150+16 mm²) for large mobile mining excavators and primary crushers. |
| BS 6708 Type 7 / 7M / 7S (640/1100V Coalcutter Trailing) | BS 6708 Type 7 / 7M / 7S (640/1100V Coalcutter Trailing): Low-voltage 640/1100 V unarmoured coalcutter trailing cables (16–150 mm²) for standard face shearers and roadheaders. |
Frequently Asked Questions (FAQ)
Key engineering FAQs on BS 6708 Type 630 vs Type 631 earthing, 15 kV routine dielectric testing, and minimum bend radii.
When should I choose BS 6708 Type 631 instead of Type 630?
Select Type 630 (3-core) when your 6.6 kV switchgear bonds the three contacting phase screens in parallel with the heavy galvanized steel pliable wire armour as the collective earth conductor. Select Type 631 (3×50+35 or 3×70+50 mm²) when local mine regulations require a dedicated insulated tinned copper earth core inside the armour.
What dielectric withstand test is applied to BS 6708 Type 630 and Type 631?
Every production drum is routine-tested at 15 kV AC across the 5.0 mm EPR medium-voltage insulation prior to dispatch, accompanied by full conductor, screen, and armour DC resistance test reports.
Can Type 630 and Type 631 be terminated into 6.6 kV flameproof bolted couplers?
Yes. Both cables are dimensionally compatible with standard British mining 6.6 kV 300 A / 400 A bolted couplers and Ex d transformer HV cable boxes.
Request Pricing for BS 6708 Type 630 or Type 631 6.6 kV Cable
Send your required type (Type 630 or Type 631), cross-section (35–150 mm²), and drum cut lengths for direct TEBAOFLEX factory pricing.
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