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Mining trailing & reeling cablesBS 6708:1998 Type 321 / 3311,900/3,300 V · 25–150 mm²Pliable GSW Armoured Trailing

BS 6708 Type 321 & 331 Armoured Trailing Cable (1.9/3.3 kV)1,900/3,300 V pliable galvanised steel wire armoured 4-core trailing cable (25–150 mm²)

BS 6708:1998 Type 321 (unscreened) and Type 331 (screened phase cores) pliable-armoured 1,900/3,300 V trailing cables with three MEPR phase cores, earth core, PCP inner sheath, pliable steel wire armour and PCP sheath.

EMC screen

Flame-retardant

Oil-resistant

Water-resistant

Preview configuration

Order designation: Type 331 · 3×70 + 50E (Scr)
Phase size: 70 mm²
Earth size: 50 mm²
Max. OD: 84.6 mm
Mass ≈: 12,400 kg/km

Check against my drum All sizes (12)

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

Rated voltage: 1,900/3,300 V
Core arrangement: 3P + 1E + PWA
Phase size range: 25–150 mm²
Ampacity (25 °C): 110–320 A
Operating temp.: −25 to +85 °C
Min. bend radius: 10 × OD (620+)

Typical values for this cable type, based on BS 6708:1998 · IEC 60228 Class 5 — confirmed in the datasheet and quotation for your order.

Application fit

Is BS 6708 Type 321 & Type 331 (1.9/3.3 kV) right for your machine?

Medium-voltage (1.9/3.3 kV) pliable wire-armoured underground mine roadway and pantechnicon feeder cable to BS 6708 Type 321 & Type 331.

Mine roadway & tunnel wall hangers

Suitable

Primary duty — 3.3 kV roadway feeder hung on arch brackets feeding face gate-end transformers.

Trailing & towing

Suitable

Pliable wire armour allows semi-mobile flitting behind advancing pantechnicon trains.

Fixed installation

Suitable

Armoured protection against rock impact in underground roadways and incline drifts.

Longwall shearer & Bretby handler

Not suitable

For 3.3 kV shearers in Bretby handlers, use unarmoured flexible Type 307 instead.

Use BS 6708 Type 307

Motorised monospiral reel

Not suitable

Armoured construction is for roadway suspension/flitting, not continuous motorized reeling.

Use (N)TSCGEWÖU MV Reel

Typical machinesUnderground mine roadway extension feedersQuarry electric shovels & mobile crushersCoalface gate-end box interconnectionsOpen-cast dewatering pump feedersMobile skid substation linksMechanically exposed 3.3 kV trailing routes

Construction

Layer by layer

Three flexible Class 5 tinned annealed copper phase cores (Red, Yellow, Brown) and one insulated earth core with MEPR insulation are laid up around a profiled elastomeric centre (with individual tinned-copper/nylon braided screens over the 3 phase cores on Type 331; unscreened on Type 321), enclosed by an extruded PCP inner bedding sheath, stranded pliable galvanised steel wire armour and a heavy-duty flame-retardant black PCP outer sheath with a blue longitudinal stripe.

Schematic, not to scale — generated from the layer data

#	Layer	Material & reference
1	Flexible phase & earth conductors (4)	Flexible stranded tinned annealed copper wire (IEC 60228 Class 5, 25 to 150 mm²)IEC 60228 Class 5
2	MEPR core insulation	Mining-grade ethylene propylene rubber (MEPR) on all 3 phase cores (Red, Yellow, Brown) and earth coreBS 6708:1998 (6.5 kV test)
3	Composite copper / nylon phase screen (Type 331)	Tinned copper wire and nylon braided screen over each of the 3 phase cores (omitted on Type 321 and earth core)Type 331 phase screen
4	Elastomeric centre	Shaped central elastomeric filler maintaining 4-core geometry under impactBS 6708:1998
5	Extruded PCP inner bedding sheath	Polychloroprene (PCP) elastomeric inner sheath (42.2 to 74.0 mm diameter)BS 6708:1998
6	Pliable galvanised steel wire armour	Stranded galvanised steel pliable wire armour (PWA, 0.240 to 0.990 Ω/km at 20 °C)BS 6708:1998
7	Heavy-duty PCP outer sheath	Heavy-duty flame-retardant polychloroprene (PCP) compound, black with longitudinal blue identification stripeBS 6708:1998

BS 6708 Type 331 (25–150 mm² · Screened)

3 copper/nylon braided-screened MEPR phase cores + 1 unscreened MEPR earth core (16–70 mm²) + pliable GSW armour

BS 6708 Type 321 (35–120 mm² · Unscreened)

3 unscreened MEPR phase cores + 1 equal-CSA unscreened MEPR earth core (35–120 mm²) + pliable GSW armour

Technical data

Ratings & operating limits

Typical values: Typical values for this cable type, based on BS 6708:1998 · IEC 60228 Class 5. Values for your order are confirmed in the datasheet and quotation.

Electrical

Rated voltage U0/U: 1,900/3,300 V AC · 6.5 kV routine AC test voltage
Current rating (25 °C): 110 to 320 A continuous at 25 °C ambient (Type 331) · 135 to 295 A (Type 321)
Core screening & earth path: Type 331: Composite Cu/nylon braid on 3 phase cores (0.55–1.35 Ω/km parallel) + insulated earth + pliable GSW armour · Type 321: Unscreened cores + full-size earth + pliable GSW armour

Thermal

Ambient temperature range: −25 °C to +85 °C
Max. conductor temperature: +90 °C continuous MEPR operating temperature

Mechanical

Min. bending radius: 620–980 mm (Type 331) · 640–940 mm (Type 321) (~10 × max OD)
Max. pulling tension: 540 to 2,000 kgf (Type 331) · 840 to 2,000 kgf (Type 321)
Armour & sheaths: Extruded PCP inner bedding sheath + pliable galvanised steel wire armour (PWA) + heavy-duty black PCP outer sheath with blue stripe

Resistance

Crush & impact protection: Pliable galvanised steel wire armour over PCP inner sheath resists rockfall and quarry vehicle run-over
Flame, oil & water: Heavy-duty flame-retardant polychloroprene (PCP) outer sheath resists oil, mine water and abrasion

Reference standards

Construction standard: BS 6708:1998 (Flexible cables for use at mines and quarries)
Conductor & insulation: IEC 60228 Class 5 tinned annealed copper · mining-grade EPR (MEPR) insulation
Routine electrical test: 6.5 kV AC routine dielectric test · min. 600–1,250 MΩ·km insulation resistance at 20 °C

Identification

Phase core identification: Red, Yellow and Brown phase cores + insulated earth core
Outer sheath marking: Black heavy-duty PCP outer sheath with longitudinal blue identification stripe

Sizes

12 standard sizes across BS 6708 Type 331 (Screened) & Type 321 (Unscreened) (1,900/3,300 V)

Switch between dimensional/mechanical data and electrical parameters (25 °C ambient).

Dimensions & mechanical
Designation BS 6708 Type	Phase mm²	Earth mm²	Phase insul. Ø mm	Phase screen Ø mm	Earth insul. Ø mm	Inner min Ø mm	Inner max Ø mm	Min. OD mm	Max. OD mm	Min. bend mm	Max. pull kgf	Mass ≈ kg/km
Type 331 · 3×25 + 16E (Scr)	25	16	13.50	15.50	15.50	42.20	44.70	57.80	61.60	620	540	6,400
Type 331 · 3×35 + 25E (Scr)	35	25	15.10	17.10	17.10	48.20	50.70	64.60	68.40	690	780	7,800
Type 331 · 3×50 + 35E (Scr)	50	35	16.20	18.20	18.20	52.60	55.60	69.80	73.80	740	1,110	9,100
Type 331 · 3×70 + 50E (Scr)	70	50	18.15	20.15	20.15	60.00	63.00	80.30	84.60	850	1,560	12,400
Type 331 · 3×95 + 70E (Scr)	95	70	19.60	21.60	21.60	65.10	68.90	86.40	90.70	910	2,000	14,600
Type 331 · 3×120 + 70E (Scr)	120	70	21.95	23.95	23.95	68.80	72.60	90.90	95.20	960	2,000	16,300
Type 331 · 3×150 + 70E (Scr)	150	70	23.10	25.40	25.40	71.50	74.00	93.80	98.10	980	2,000	18,200
Type 321 · 3×35 + 35E (Unscr)	35	35	15.10	Unscreened	15.10	44.30	46.80	60.30	64.10	640	840	4,900
Type 321 · 3×50 + 50E (Unscr)	50	50	16.20	Unscreened	16.20	51.30	54.30	68.30	72.30	720	1,200	6,400
Type 321 · 3×70 + 70E (Unscr)	70	70	18.15	Unscreened	18.15	56.40	59.40	74.40	78.40	790	1,680	7,700
Type 321 · 3×95 + 95E (Unscr)	95	95	19.60	Unscreened	19.60	63.80	66.80	84.90	89.20	890	2,000	10,800
Type 321 · 3×120 + 120E (Unscr)	120	120	21.95	Unscreened	21.95	67.50	71.30	89.40	93.70	940	2,000	12,300

Typical values for this cable type; dimensions and weights for your order are confirmed in the quotation.
In Type 331, the unscreened earth core insulation is built up to match the diameter over the screened phase cores (15.50–25.40 mm) so all four cores form a symmetrical assembly.
In Type 321, all four unscreened cores (3 phase + 1 earth) have identical copper cross-sections and insulated diameters (15.10–21.95 mm).

Electrical parameters (25 °C)
Designation BS 6708 Type	Cont. current A (25 °C)	Phase DC 20 °C Ω/km	Earth DC 20 °C Ω/km	3 screens par. Ω/km	Armour DC 20 °C Ω/km	Reactance 50 Hz Ω/km	Reactance 60 Hz Ω/km	Min. IR 20 °C MΩ·km	3-ph V-drop mV/A/m
Type 331 · 3×25 + 16E (Scr)	110	0.795	1.240	1.350	0.965	0.125	0.150	1,250	1.69
Type 331 · 3×35 + 25E (Scr)	135	0.565	0.795	0.800	0.844	0.117	0.140	1,100	1.21
Type 331 · 3×50 + 35E (Scr)	170	0.393	0.565	0.700	0.715	0.113	0.136	950	0.85
Type 331 · 3×70 + 50E (Scr)	205	0.277	0.393	0.690	0.488	0.108	0.129	820	0.61
Type 331 · 3×95 + 70E (Scr)	250	0.210	0.277	0.840	0.382	0.105	0.126	720	0.48
Type 331 · 3×120 + 70E (Scr)	295	0.164	0.277	0.550	0.299	0.101	0.121	660	0.39
Type 331 · 3×150 + 70E (Scr)	320	0.132	0.277	0.550	0.240	0.098	0.118	600	0.32
Type 321 · 3×35 + 35E (Unscr)	135	0.565	0.565	—	0.990	0.117	0.140	1,100	1.21
Type 321 · 3×50 + 50E (Unscr)	170	0.393	0.393	—	0.760	0.113	0.136	950	0.85
Type 321 · 3×70 + 70E (Unscr)	205	0.277	0.277	—	0.530	0.108	0.129	820	0.61
Type 321 · 3×95 + 95E (Unscr)	250	0.210	0.210	—	0.400	0.105	0.126	720	0.48
Type 321 · 3×120 + 120E (Unscr)	295	0.164	0.164	—	0.320	0.101	0.121	660	0.39

Armour DC resistance at 20 °C (0.240–0.990 Ω/km) works in parallel with the insulated earth core (and the 3 phase screens on Type 331) to provide high earth-fault conductivity.

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 1,692 mm

Minimum bending radius: 846 mm
Min. drum core diameter: ≈ 1,692 mm
Cable weight on drum: 1,240.0 kg
Outer diameter: 84.6 mm

Indicative only: based on the datasheet outer diameter and 10 × 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
6.5 kV AC dielectric withstand test	6.5 kV AC routine voltage test on 1,900/3,300 V MEPR-insulated cores per BS 6708:1998	Every shipping drum
Phase, earth, screen & armour DC resistance	Verified on all phase conductors, earth core, 3 parallel screens (Type 331) and pliable steel wire armour per BS 6708:1998	Every shipping drum
Sample tests
PCP sheath flame, oil & mechanical testing	Heavy-duty flame-retardant black PCP outer sheath with blue stripe tested to BS 6708:1998	Production batch

Inspection certificate

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

Product approvals

BS 6708:1998 Type 321 / 331CE · LVDRoHS · REACH

Company certificates

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

Marking & supply

Ordering & delivery

Sheath marking

TEBAOFLEX · BS 6708:1998 · TYPE 321 / TYPE 331 · 1900/3300V (BLUE STRIPE)

Delivery form: Export seaworthy fumigated wooden drums matched to 10 × OD bend radius
Lengths: Standard drum lengths or custom cut lengths with gland termination allowance
Certificate: EN 10204 3.1 factory routine test certificate with every drum
Quote response: Engineering specification and quote within 2 business hours

Technical documents

Downloads

PDFBS 6708 Type 321 & 331 Armoured Trailing Cable (1.9/3.3 kV) – technical datasheet12 sizes · construction, technical data, approvals XLSXBS 6708 Type 321 & Type 331 (1.9/3.3 kV) spec data (Excel)All 12 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 321 and Type 331?

Both are 1,900/3,300 V 4-core pliable galvanised steel wire armoured trailing cables under BS 6708:1998. Type 331 (25–150 mm²) adds individual composite tinned-copper/nylon braided screens over the three MEPR phase cores plus an unscreened insulated earth core (16–70 mm²). Type 321 (35–120 mm²) has unscreened phase cores and a full-size unscreened earth core equal in cross-section to the phase conductors.

Why does the earth core in Type 331 have the same insulated diameter as the screened phase cores?

Although the earth conductor in Type 331 has a reduced copper cross-section (e.g. 50 mm² earth with 70 mm² phases), its MEPR insulation is extruded to the exact outer diameter of the screened phase cores (20.15 mm) so all four cores lay up symmetrically around the elastomeric centre.

Why is the black PCP outer sheath marked with a blue longitudinal stripe?

Under BS 6708:1998, a longitudinal blue stripe on the black polychloroprene (PCP) outer sheath identifies a 1,900/3,300 V pliable-armoured mining cable in underground roadways and surface quarries.

What is the minimum bending radius for Type 321 and Type 331 cables?

The minimum bending radius is approximately 10 × Maximum Overall Diameter (620 to 980 mm on Type 331; 640 to 940 mm on Type 321).

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BS 6708 Type 321 & Type 331 Armoured Trailing Cable

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Reel & motion:
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Datasheet Request a quote

BS 6708 Type 321 & 331 Armoured Trailing Cable (1.9/3.3 kV)1,900/3,300 V pliable galvanised steel wire armoured 4-core trailing cable (25–150 mm²)

Mine roadway & tunnel wall hangers

Trailing & towing

Fixed installation

Longwall shearer & Bretby handler

Motorised monospiral reel

BS 6708 Type 331 (25–150 mm² · Screened)

BS 6708 Type 321 (35–120 mm² · Unscreened)

Electrical

Thermal

Mechanical

Resistance

Reference standards

Identification

Check results

Inspection certificate

Product approvals

Company certificates

01Selected sizes

02Reel & motion

03Message for our engineers

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