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Product

Mining trailing & reeling cablesBS 6708640/1,100 V · Types 20 & 21Pliable Wire Armour

BS 6708 Type 20 & Type 21 Pliable Wire Armoured Mining Cable640/1,100 V 3-core & 4-core elastomeric-cradle cables with galvanized steel PWA

640/1,100 V pliable wire-armoured mining cables to BS 6708:1998 in 3-core (Type 20) and 4-core (Type 21) constructions from 2.5 to 150 mm², featuring EPR insulation, elastomeric cradle core separation, 7-strand galvanized steel armour and PCP sheath.

Outdoor & humid

Oil-resistant

Flame-retardant

Water-resistant

Preview configuration

Order designation: Type 21 · 4×35
Max. OD: 56.1 mm
Min. bend R: 505 mm
Mass ≈: 5,220 kg/km
Cont. current: 135 A

Check against my drum All sizes (24)

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Engineering reply in 2 business hoursCut-to-length export drumsEN 10204 3.1 certificate per drum

Rated voltage: 640/1,100 V
Core layout: 3C / 4C + PWA
CSA range: 2.5–150 mm²
Max. conductor T: +90 °C
Min. operating T: −25 °C
Min. bend radius: 9 × OD

Typical values for this cable type, based on BS 6708 — confirmed in the datasheet and quotation for your order.

Application fit

Is BS 6708 Type 20 / 21 Armoured right for your machine?

Pliable galvanized-steel-wire-armoured (SWA) underground coal-mine roadway and stage-loader cable to BS 6708 Type 20 & Type 21 (640/1100 V).

Mine roadway & tunnel wall hangers

Suitable

Primary duty — suspended on gate-road arch hooks between district transformers and gate-end boxes.

Fixed installation

Suitable

Heavy crush-resistant armoured feeder along underground drifts, roadways and transfer points.

Trailing & towing

With conditions

Pliable wire armour allows periodic flitting as the longwall gate-end pantechnicon advances.

Longwall shearer & Bretby handler

Not suitable

Pliable wire armour is for roadway flitting, not continuous shearer Bretby flexing.

Use BS 6708 Type 7 Shearer

Motorised monospiral reel

Not suitable

Steel-wire armour cannot be wound onto motorised reeling drums.

Use BS 6708 Type 7 / 11

Typical machinesMine roadway power distributionGate-end box & transformer interlinksQuarry crushers & screening plantExcavating & loading machinesDeep-mine gassy workingsHeavy-impact surface mining feeders

Construction

Layer by layer

Three (Type 20) or four (Type 21) Class 5 tinned copper conductors insulated with EPR and wrapped with coloured textile identification tape are laid up around a profiled elastomeric cradle without contacting each other, enclosed in an extruded rubber inner sheath (2.0 to 5.0 mm), armoured with 7-strand galvanized steel pliable wire armour (PWA) and finished with a heavy-duty black chloroprene (PCP) outer sheath (2.5 to 7.3 mm).

Schematic, not to scale — generated from the layer data

#	Layer	Material & reference
1	Flexible conductors	Electrolytic stranded tinned copper wire, IEC 60228 Class 5 (2.5 to 150 mm²)IEC 60228 Class 5
2	Core insulation	EPR (ethylene-propylene rubber), 1.4 to 2.3 mm radial thicknessBS 7655 / BS 6708
3	Identification tape	Coloured textile tape applied over EPR insulation for core identificationCore identification
4	Elastomeric cradle	Profiled elastomeric cradle separating all cores so they do not contact one anotherNon-contact cradle
5	Inner sheath	Extruded rubber inner bedding sheath (2.0 to 5.0 mm radial thickness)Armour bedding
6	Pliable wire armour (PWA)	Galvanized steel 7-wire strands (7/0.45, 7/0.71, 7/0.90 or 7/1.25 mm) providing mechanical crush protection and collective earth pathBS 6708 PWA
7	Outer sheath	Heavy-duty flame-retardant polychloroprene (chloroprene / PCP) outer sheath, black (2.5 to 7.3 mm radial thickness)BS 6708 / BS 7655 EM2

BS 6708 Type 20 · 3×2.5 to 3×150 mm²

3 unscreened EPR cores around non-contact elastomeric cradle + rubber inner sheath + galvanized steel PWA (0.45–4.6 Ω/km) + PCP jacket

BS 6708 Type 21 · 4×2.5 to 4×150 mm²

4 unscreened EPR cores around non-contact elastomeric cradle + rubber inner sheath + galvanized steel PWA (0.41–4.2 Ω/km) + PCP jacket

Technical data

Ratings & operating limits

Typical values: Typical values for this cable type, based on BS 6708. Values for your order are confirmed in the datasheet and quotation.

Electrical

Rated voltage (U0/U): 640/1,100 V AC (U0/U)
AC test voltage: 3.0 kV AC dielectric test on insulated cores
Current ratings (25 °C): 28 to 320 A continuous at 25 °C ambient across 2.5 to 150 mm²
Armour DC resistance (20 °C): 0.45 to 4.6 Ω/km (Type 20 armour at 20 °C) · 0.41 to 4.2 Ω/km (Type 21 armour at 20 °C)

Thermal

Max. conductor temperature: +90 °C maximum continuous conductor temperature (EPR insulation)
Operating temperature range: −25 °C to +85 °C ambient installation / service range (current ratings referenced at 25 °C)

Mechanical

Pliable wire armour (PWA): Galvanized steel pliable wire armour (PWA) stranded in 7-wire bundles: 7/0.45 mm (2.5–4 mm²), 7/0.71 mm (6–16 mm²), 7/0.90 mm (25–120 mm²), 7/1.25 mm (150 mm²)
Minimum bending radius: 243 to 786 mm (Type 20) · 258 to 858 mm (Type 21), corresponding to 9 × maximum OD
Cradle, inner & outer sheaths: Cores laid up without contact around an elastomeric cradle + rubber inner sheath (2.0 to 5.0 mm) + PWA + heavy-duty chloroprene outer sheath (2.5 to 7.3 mm)

Resistance

Flame retardance: Flame retardant polychloroprene outer sheath to BS 6708 / BS EN 60332-1-2
Crush & mine environment: Pliable galvanized steel wire armour + heavy-duty PCP sheath resists rockfall impact, crushing, rodent attack, mineral oils and mine water

Reference standards

Standards compliance: BS 6708 (Types 20 & 21); IEC 60228 Class 5; BS 7655
Designated duty: Semi-flexible roadway power distribution, gate-end interconnects, quarry feeders and armoured machine connections

Identification

Core identification & separation: Coloured textile separator tape over EPR core insulation; Type 20 has 3 cores, Type 21 has 4 cores laid up without mutual contact around an elastomeric cradle
Outer sheath: Heavy-duty black chloroprene (PCP) outer sheath

Sizes

24 configurations across BS 6708 Type 20 (3-core, 12 sizes) & Type 21 (4-core, 12 sizes)

Complete dimensional, armour, weight, current rating and conductor/armour DC resistance data from 2.5 to 150 mm².

Dimensions, armour & electrical
Type · nominal CSA mm²	Conductor stranding	Cond. Ø mm	Insul. mm	Inner sh. mm	Armour strand	Outer sh. mm	Max. OD mm	Min. R mm	Mass ≈ kg/km	Cu wt kg/km	Current (25 °C) A	Cond. DC res. Ω/km	Armour DC res. Ω/km
BS 6708 Type 20 · 640/1,100 V (3-Core Pliable Wire Armoured)
Type 20 · 3×2.5	50/0.25	2.10	1.4	2.0	7/0.45	2.5	26.9	243	990	72	28	8.210	4.60
Type 20 · 3×4	56/0.30	2.70	1.4	2.0	7/0.45	2.5	28.2	254	1,150	115	37	5.090	4.20
Type 20 · 3×6	84/0.30	3.30	1.5	2.5	7/0.71	3.8	36.5	329	2,000	173	46	3.390	2.20
Type 20 · 3×10	80/0.40	4.40	1.5	2.5	7/0.71	3.8	38.4	346	2,350	288	63	1.950	2.00
Type 20 · 3×16	126/0.40	5.50	1.5	2.5	7/0.71	3.8	40.8	368	2,750	461	85	1.240	1.90
Type 20 · 3×25	196/0.40	7.10	1.6	2.5	7/0.90	4.0	47.0	423	3,350	720	110	0.795	1.30
Type 20 · 3×35	276/0.40	8.40	1.6	2.5	7/0.90	4.3	50.6	456	4,300	1,008	135	0.565	1.20
Type 20 · 3×50	396/0.40	10.10	1.7	2.5	7/0.90	4.7	56.7	511	5,320	1,440	170	0.393	1.10
Type 20 · 3×70	360/0.50	11.90	1.8	2.5	7/0.90	5.2	62.7	565	6,750	2,016	205	0.277	0.94
Type 20 · 3×95	475/0.50	13.90	2.0	3.8	7/0.90	5.8	72.1	649	8,750	2,736	250	0.210	0.80
Type 20 · 3×120	629/0.50	15.80	2.2	3.8	7/0.90	6.2	77.0	693	10,650	3,456	295	0.164	0.74
Type 20 · 3×150	740/0.50	17.00	2.3	5.0	7/1.25	6.6	87.3	786	12,500	4,320	320	0.132	0.45
BS 6708 Type 21 · 640/1,100 V (4-Core Pliable Wire Armoured)
Type 21 · 4×2.5	50/0.25	2.10	1.4	2.0	7/0.45	2.5	28.6	258	1,150	96	28	8.210	4.20
Type 21 · 4×4	56/0.30	2.70	1.4	2.0	7/0.45	2.5	30.1	271	1,320	154	37	5.090	3.90
Type 21 · 4×6	84/0.30	3.30	1.5	2.5	7/0.71	3.8	38.8	350	2,350	230	46	3.390	2.00
Type 21 · 4×10	80/0.40	4.40	1.5	2.5	7/0.71	3.8	41.0	369	2,740	384	63	1.950	1.90
Type 21 · 4×16	126/0.40	5.50	1.5	2.5	7/0.71	3.9	44.0	396	3,170	614	85	1.240	1.70
Type 21 · 4×25	196/0.40	7.10	1.6	2.5	7/0.90	4.3	49.8	449	4,030	960	110	0.795	1.50
Type 21 · 4×35	276/0.40	8.40	1.6	2.5	7/0.90	4.7	56.1	505	5,220	1,344	135	0.565	1.10
Type 21 · 4×50	396/0.40	10.10	1.7	2.5	7/0.90	5.1	61.8	557	6,400	1,920	170	0.393	0.96
Type 21 · 4×70	360/0.50	11.90	1.8	2.5	7/0.90	5.7	71.4	643	8,060	2,688	205	0.277	0.80
Type 21 · 4×95	475/0.50	13.90	2.0	3.8	7/0.90	6.3	78.6	708	10,650	3,648	250	0.210	0.73
Type 21 · 4×120	629/0.50	15.80	2.2	3.8	7/0.90	6.8	89.0	801	13,450	4,608	295	0.164	0.47
Type 21 · 4×150	740/0.50	17.00	2.3	5.0	7/1.25	7.3	95.3	858	15,300	5,760	320	0.132	0.41

Typical values for this cable type; dimensions and weights for your order are confirmed in the quotation.
Pliable wire armour consists of 7-wire galvanized steel strands laid helically between the rubber inner sheath and heavy-duty chloroprene outer sheath.

Reel check

Will it fit your machine?

A first screen using datasheet values. Engineering confirms drum geometry, acceleration and tension with your quotation.

Cable sizeDrum core diameter (mm)

Cable length on drum (m)

Enter your drum core diameterMinimum for this size is about 1,010 mm

Minimum bending radius: 505 mm
Min. drum core diameter: ≈ 1,010 mm
Cable weight on drum: 522.0 kg
Outer diameter: 56.1 mm

Indicative only: based on the datasheet outer diameter and 9 × OD bending radius. Current derating for wound layers per DIN VDE 0298-4 is assessed separately.

Quality & approvals

Testing & inspection

Routine tests on every production length, sample and type tests per batch — documented on an EN 10204 3.1 inspection certificate.

ConductorClass 5 stranding
Spark test100 % in-line
Lay-upCores, earth, fillers
SheathingInner, braid / screen, outer
Electrical testsAC voltage, resistance
DimensionsOD, wall thickness
Inspection documents & dispatchDrum & dispatch

Testing & inspection	Test value / reference	Frequency
Routine tests
AC high-voltage dielectric test	3.0 kV AC applied between conductors and between each conductor and pliable wire armour	Every drum
Conductor & armour DC resistance check	Verified at 20 °C against BS 6708 limits (0.132–8.21 Ω/km conductor; 0.41–4.6 Ω/km armour)	Every drum
Sample tests
Flame retardance test	Self-extinguishing heavy-duty chloroprene outer sheath per BS 6708 / BS EN 60332-1-2	Production batch
Armour strand & sheath dimensional inspection	Verification of 7-wire galvanized steel armour strand diameter, inner rubber sheath and outer PCP sheath wall	Every drum

Inspection certificate

Issued with every drum, listing the routine test results for that length.

Product approvals

BS 6708CE · LVDRoHS · REACH

Company certificates

ISO 9001ISO 14001ISO 45001VDE marks approvalUL / cULCE · LVD / EMC

Marking & supply

Ordering & delivery

Sheath marking

TEBAOFLEX · BS 6708 TYPE 20 (or TYPE 21) · 640/1100 V · [size] · ARMOURED PCP

Delivery form: Heat-treated seaworthy wooden drums lagged with solid timber battens
Lengths: Custom cut-to-length reels per mine roadway schedule
Certificate: EN 10204 3.1 inspection certificate with every dispatch
Quote response: Engineering specification and quote within 2 business hours

Technical documents

Downloads

PDFBS 6708 Type 20 & Type 21 Pliable Wire Armoured Mining Cable – technical datasheet24 sizes · construction, technical data, approvals XLSXBS 6708 Type 20 / 21 Armoured spec data (Excel)All 24 sizes with dimensions and data, for your BOM or quotation

Revision: 2026-10-20
Updated: 2026-10-20

FAQ

Questions engineers ask first

Not covered here? Send your drawing — an engineer replies within 2 business hours.

What is the difference between BS 6708 Type 20 and Type 21?

Both are 640/1,100 V pliable wire-armoured mining cables with unscreened EPR-insulated cores laid up around a non-contact elastomeric cradle, a rubber inner sheath, 7-strand galvanized steel armour and a heavy-duty PCP outer sheath. Type 20 has 3 cores (3×2.5 to 3×150 mm²) whereas Type 21 has 4 cores (4×2.5 to 4×150 mm²).

How do BS 6708 Type 20/21 differ from Type 201/211 armoured cables?

Types 20 and 21 have unscreened cores separated by an elastomeric cradle and rely on the galvanized steel pliable wire armour as the collective metallic screen/earth. Types 201 and 211 add individual composite copper/nylon braided screens over each phase core beneath the inner sheath and pliable wire armour, plus a longitudinal yellow identification stripe on the outer sheath.

Why does BS 6708 use 7-wire stranded armour instead of single-wire SWA?

Single-wire armour (SWA) is rigid and kinks when moved. BS 6708 specifies pliable wire armour (PWA) made of 7-wire galvanized steel strands (7/0.45 to 7/1.25 mm) laid helically over a rubber inner sheath, allowing the cable to flex to a 9 × OD bending radius as mine roadways advance.

Can the pliable wire armour carry earth-fault current?

Yes. The 7-strand galvanized steel armour has a published maximum DC resistance at 20 °C ranging from 4.6 Ω/km on 3×2.5 mm² down to 0.41 Ω/km on 4×150 mm², providing a robust metallic earth path.

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03Message for our engineers

BS 6708 Type 20 & Type 21 Armoured Cable

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Reel & motion:
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