4 Core Armoured Cable: SWA/STA Sizes, Specifications & Factory Direct Price

Q: How deep should 4 core armoured cable be buried?

Standard burial depths per BS 7671 and IEC 60364: - Under roads/driveways: 600mm minimum - In gardens/fields: 500mm minimum - Under building foundations: Not recommended without ducting - Lay cable on 50mm of fine sand, cover with 50mm sand, then place cable marker tape 150mm above The cable's steel armour provides mechanical protection, but depth provides additional safety margin against spade/excavator damage.

Q: What is the maximum operating temperature?

XLPE insulated (standard): 90°C continuous, 250°C short-circuit (5 seconds) - PVC insulated: 70°C continuous, 160°C short-circuit XLPE allows approximately 20% higher current rating than PVC for the same conductor size due to the higher operating temperature limit.

Key Takeaway

Complete 4 core armoured cable specifications table (1.5mm² to 800mm²), current ratings, SWA vs STA comparison, IEC 60502-1 & BS 5467 compliance. Get factory direct pricing from China Cable Factory.

Looking for 4 core armoured cable with verified specifications and competitive factory pricing? This guide covers everything procurement engineers and project managers need: full size charts from 1.5mm² to 800mm², current carrying capacities for every installation method, the key differences between SWA and STA armouring, and what to look for when sourcing from a Chinese manufacturer.

We produce 4 core armoured cables at our Henan factory — certified to IEC 60502-1, BS 5467, and GB/T 12706. Our annual output exceeds 15,000 km of armoured cable across all voltage classes. Below is what we know from manufacturing and exporting to projects across Africa, the Middle East, and Southeast Asia.

What Is 4 Core Armoured Cable?

A 4 core armoured cable is a power cable containing four insulated copper or aluminium conductors, protected by a metallic armour layer (steel wire or steel tape) beneath an outer PVC or LSZH sheath. The "4 core" configuration is specifically designed for three-phase power distribution with a neutral conductor.

Construction layers (outside to inside):

Outer sheath — PVC (standard) or LSZH (low smoke environments) — provides UV, moisture, and chemical protection
Steel armour — galvanised steel wires (SWA) or steel tape (STA) — delivers mechanical protection against impact, compression, and rodent damage
Bedding — PVC layer between armour and insulation cores — prevents armour from damaging insulation
Insulation — XLPE (cross-linked polyethylene) — rated for 90°C continuous conductor temperature
Conductors — 4× stranded copper (Class 2 per BS EN 60228) or solid aluminium (Class 1)

4 core armoured cable cross section showing copper conductors, XLPE insulation, steel wire armour and PVC sheath — Cross section of a 4 core XLPE/SWA/PVC armoured cable — four copper conductors with XLPE insulation, PVC bedding, galvanised steel wire armour, and black PVC outer sheath

4 core SWA cable structure showing aluminium conductors with color coded insulation — 4 core steel wire armoured cable with colour-coded conductor insulation for three-phase identification

Why 4 cores?

In a three-phase electrical system, you need three phase conductors (L1, L2, L3) plus a neutral (N). A 4 core cable carries all four in one run — eliminating the need for separate neutral cables and reducing installation labour and cost. For installations requiring an earth conductor, a 5 core cable (3 phases + neutral + earth) or the steel armour itself (used as CPC in BS 7671 installations) provides the earth path.

Core identification colours (per BS 7671 / IEC 60446):

Brown (L1), Black (L2), Grey (L3), Blue (Neutral)

4 Core Armoured Cable Specifications & Size Chart

The following table provides complete specifications for 4 core copper conductor XLPE/SWA/PVC armoured cables manufactured to IEC 60502-1. All values are based on standard production parameters.

Physical Dimensions & Weight

Conductor Size (mm²)	Insulation Thickness (mm)	Armour Wire Ø (mm)	Overall Cable Ø (mm)	Weight (kg/km)
1.5	0.7	0.9	15.0	415
2.5	0.7	0.9	16.0	490
4	0.7	0.9	17.0	600
6	0.7	0.9	19.0	815
10	0.7	1.25	22.0	1,070
16	0.7	1.6	25.0	1,540
25	0.9	1.6	26.5	1,985
35	0.9	1.6	29.0	2,475
50	1.0	1.6	32.5	3,100
70	1.1	2.0	38.0	4,480
95	1.1	2.0	42.5	5,750
120	1.2	2.5	48.0	7,460
150	1.4	2.5	52.5	8,810
185	1.6	2.5	58.5	10,780
240	1.7	2.5	67.0	13,930
300	1.8	2.5	72.0	16,850
400	2.0	3.15	83.0	22,230
500	2.2	3.15	91.0	27,500
630	2.4	3.15	101.0	34,100
800	2.6	3.15	113.0	43,200

Data per IEC 60502-1 Design 1, copper conductor, XLPE insulated, PVC sheathed. Actual values may vary ±5% depending on conductor class and manufacturing tolerances.

Current Carrying Capacity (Ampacity)

Current ratings below are for 4 core cables operating at three-phase AC, with a maximum conductor temperature of 90°C (XLPE insulation).

Conductor Size (mm²)	Clipped Direct (A)	In Free Air (A)	Direct Buried (A)
1.5	23	25	21
2.5	31	33	28
4	42	44	36
6	53	56	44
10	73	78	58
16	94	99	75
25	124	131	96
35	154	162	115
50	187	197	135
70	238	251	167
95	289	304	197
120	335	353	223
150	386	406	251
185	441	463	281
240	520	546	324
300	599	628	365
400	673	728	—
500	770	833	—
630	878	950	—
800	990	1070	—

Reference conditions:

Ambient air temperature: 30°C
Ground temperature: 20°C
Burial depth: 0.5m
Soil thermal resistivity: 1.2 K·m/W
Single circuit, no grouping

If installing multiple cables in the same trench or ambient temperatures differ, apply derating factors per IEC 60364-5-52 or BS 7671 Appendix 4.

Voltage Drop (mV/A/m) — Three-Phase

Conductor Size (mm²)	Voltage Drop (mV/A/m)
1.5	27
2.5	16
4	10
6	6.8
10	4.0
16	2.5
25	1.65
35	1.15
50	0.87
70	0.60
95	0.45
120	0.37
150	0.30
185	0.26
240	0.21
300	0.185
400	0.170
500	0.140
630	0.115
800	0.095

Data based on BS 7671 Table 4E4B / IEC 60364 reference method D (direct buried) and C (clipped direct). For exact project calculations, request our technical data sheets with conductor resistance and reactance values.

Conductor Resistance at 20°C

Conductor Size (mm²)	Max. DC Resistance (Ω/km) — Copper	Max. DC Resistance (Ω/km) — Aluminium
1.5	12.1	—
2.5	7.41	—
4	4.61	—
6	3.08	—
10	1.83	3.08
16	1.15	1.91
25	0.727	1.20
35	0.524	0.868
50	0.387	0.641
70	0.268	0.443
95	0.193	0.320
120	0.153	0.253
150	0.124	0.206
185	0.0991	0.164
240	0.0754	0.125
300	0.0601	0.100
400	0.0470	0.0778
500	0.0366	0.0605
630	0.0283	0.0469
800	0.0221	0.0367

Values per BS EN 60228, Class 2 stranded copper conductors and Class 1 solid/Class 2 stranded aluminium conductors.

Types of 4 Core Armoured Cable

4 core armoured cables are classified by armour type, insulation material, voltage rating, and conductor material. Here is how they break down:

By Armour Type

Type	Full Name	Construction	Best For
SWA	Steel Wire Armoured	Helically applied galvanised steel round wires	Underground burial, areas with high mechanical risk
STA	Steel Tape Armoured	Two layers of galvanised steel tape, helically wound	Indoor/duct installations, lighter mechanical protection
AWA	Aluminium Wire Armoured	Aluminium round wires	Single-core cables (non-magnetic requirement)

By Insulation

Insulation	Max. Conductor Temp.	Short Circuit Temp.	Standard
XLPE	90°C	250°C	IEC 60502-1, BS 5467
PVC	70°C	160°C	IEC 60502-1, BS 6346
LSZH	90°C	250°C	BS 6724, IEC 60332

XLPE is the industry standard for new installations. It offers higher current capacity (90°C vs 70°C), better short-circuit performance, and lower dielectric losses compared to PVC. We manufacture PVC-insulated cables for replacement/maintenance projects but recommend XLPE for all new builds.

By Voltage Rating

Voltage Class	Designation	Typical Application
0.6/1kV	Low voltage	Building services, distribution boards, industrial
1.9/3.3kV	Medium voltage	Industrial plant feeders, motor connections
3.8/6.6kV	Medium voltage	Primary distribution, substation interconnects
6.35/11kV	Medium voltage	Utility distribution networks

This article focuses on 0.6/1kV cables — the most commonly procured type for construction and industrial projects. For medium voltage 4 core cables, see our XLPE power cable guide.

By Conductor Material

Material	Conductivity	Weight	Cost	Best For
Copper (Cu)	100% IACS	Heavier	Higher	Most applications, especially where space is limited
Aluminium (Al)	61% IACS	~50% lighter	~40% less	Long runs where weight/cost matters, utility distribution

Practical guidance: For conductor sizes ≤16mm², copper is standard. For ≥25mm², aluminium becomes economically viable — but you need one size larger to match copper's current capacity (e.g., 95mm² Al ≈ 70mm² Cu in ampacity).

Applications of 4 Core Armoured Cable

4 core SWA cable is the default choice for three-phase power distribution in construction and infrastructure. Here are the primary applications:

Underground Power Distribution

Direct burial in trenches at 500mm depth (domestic) or 600mm+ (commercial). The steel armour provides protection against spade strikes, ground movement, and rodent attack. No additional conduit is required for most installations.

Industrial Plant Wiring

Feeding motors, panels, and machinery in factories, warehouses, and processing plants. The armour protects against forklift impact, vibration, and accidental damage in high-traffic areas.

Building Services

Main incoming supply from transformer to distribution board. Sub-main distribution from main board to floor/zone distribution boards in commercial buildings, hospitals, and data centres.

Infrastructure Projects

Road lighting circuits
Water pumping stations
Sewage treatment plants
Telecommunications tower power feeds
Solar farm DC collection (with appropriate voltage rating)
Mining and quarry installations

External Above-Ground Installations

Clipped to cable trays, ladders, or structures in outdoor environments. The PVC sheath provides UV resistance and the armour prevents mechanical damage from wind-borne debris or accidental impact.

Size selection guide by application:

Application	Typical Size Range	Notes
Domestic sub-main	16–25mm²	Short runs, less than 100A demand
Small commercial incoming	35–70mm²	100–250A TPN supply
Industrial motor feed	10–95mm²	Match motor FLC + starting current
Large commercial/industrial main	120–300mm²	High-demand buildings, multiple floors
Utility distribution	185–800mm²	Primary substations, bulk supply

How to Choose the Right 4 Core Armoured Cable

Selecting the correct cable involves five key decisions:

1. Determine Required Current Capacity

Calculate the maximum design current (Ib) for the circuit. Include diversity factors where applicable. Then select a cable whose current rating (Iz) exceeds Ib after applying all derating factors:

Iz ≥ Ib / (Ca × Cg × Ci × Cc)

Where:

Ca = ambient temperature correction factor
Cg = grouping factor (multiple cables in same trench)
Ci = thermal insulation factor
Cc = burial depth correction factor

2. Check Voltage Drop

Verify the voltage drop does not exceed permitted limits:

BS 7671: 5% from origin to final circuit (3% for lighting)
IEC 60364: typically 4% distribution + 4% final circuit

Formula: Vd = (mV/A/m) × Ib × L / 1000

If voltage drop exceeds limits, go up one cable size.

3. Verify Short-Circuit Rating

The cable must withstand fault current for the duration of protective device clearance time. Use the adiabatic equation:

S ≥ √(I²t) / k

Where k = 143 for copper/XLPE, and I²t is the let-through energy of the protective device.

4. Select Armour Type (SWA vs STA)

Choose SWA for underground burial, outdoor, or any location with significant mechanical risk
Choose STA for indoor ducts, cable trays, or where lighter weight is preferred

(See detailed comparison below)

5. Choose Conductor Material

Copper — default for sizes ≤16mm², premium performance, smaller diameter
Aluminium — cost-effective for ≥50mm², lighter, larger diameter requires bigger glands

SWA vs STA: Detailed Comparison

This is one of the most common questions we receive from procurement teams. Here is the definitive comparison:

Parameter	SWA (Steel Wire Armoured)	STA (Steel Tape Armoured)
Armour construction	Round galvanised steel wires, helically applied	Two layers of steel tape, helically wound with gap
Mechanical strength	Superior — withstands direct impact, crushing	Moderate — protects against light mechanical damage
Tensile strength	High — can support cable's own weight in vertical runs	Lower — not suitable for vertical suspension
Flexibility	Less flexible, larger bend radius	More flexible, smaller bend radius
Weight	Heavier	~10-15% lighter
Diameter	Larger (due to round wire profile)	Slightly smaller
Earth fault capacity	Higher — wire armour has greater cross-section	Lower — tape has limited earth fault current capacity
Best applications	Underground, outdoor, industrial, high-risk	Indoor, ducts, cable trays, risers
Cost	Slightly higher	Slightly lower
Cable designation	e.g., XLPE/PVC/SWA/PVC	e.g., XLPE/PVC/STA/PVC

When to Use SWA

Direct burial underground (no conduit)
Outdoor installation exposed to mechanical risk
Industrial environments (factories, mines, quarries)
Where armour is used as circuit protective conductor (CPC)
Vertical cable runs (cable must support own weight)

When to Use STA

Cable ducts and enclosed trenches
Indoor cable tray/ladder installations
Where lower weight and tighter bending radius matter
Applications requiring only basic mechanical protection
Multi-core cables (3+ cores) where SWA would be excessively stiff

Our recommendation: If you are unsure, specify SWA. It costs marginally more but covers virtually all installation scenarios. STA is appropriate only when you are certain the cable will not face significant mechanical stress.

Standards & Certifications

Our 4 core armoured cables are manufactured and tested to the following international standards:

Standard	Scope	Market
IEC 60502-1	Power cables 1kV–3kV, construction and testing	International
BS 5467	XLPE insulated armoured cables 0.6/1kV and 1.9/3.3kV	UK, Commonwealth, Middle East
BS 6346	PVC insulated armoured cables 0.6/1kV	UK (legacy installations)
GB/T 12706	XLPE insulated power cables 1kV–35kV	China
NFC 33-226	Power cables for underground installation	France, North/West Africa
SANS 1507	Low voltage power cables	South Africa
AS/NZS 5000.1	Power cables for underground use	Australia, New Zealand

Our factory certifications:

ISO 9001:2015 Quality Management
ISO 14001:2015 Environmental Management
CCC (China Compulsory Certification)
CE Marking
SGS and BV third-party test reports available

All cables are subjected to routine testing including:

Conductor resistance measurement
High voltage withstand test (3.5kV for 5 minutes)
Insulation resistance test (≥100 MΩ·km)
Spark test on insulation and sheath
Dimensional verification

Type test reports to IEC 60502-1 Clause 18 are available upon request.

Why Buy 4 Core Armoured Cable from China Cable Factory?

Factory Direct Pricing

You buy directly from our manufacturing facility — no trading companies, no middlemen. This typically means 20-35% lower cost compared to sourcing through distributors or trading houses. We control every step from copper rod drawing to final cable packaging.

Production Capacity

Our factory operates 12 production lines dedicated to low-voltage armoured cables. Monthly output capacity for 4 core armoured cable alone exceeds 2,000 km. This means:

Standard sizes (4mm²–95mm²) ship from stock
Non-standard configurations manufactured within 15-20 working days
Large project orders (100+ km) handled without capacity constraints

Quality Control

Every production drum undergoes:

100% spark testing during insulation and sheath extrusion
Conductor resistance verification per drum
Sample high-voltage testing per production batch
Third-party inspection welcome (SGS, BV, TÜV)

Export Experience

We have shipped armoured cables to 45+ countries. We understand:

Documentation requirements (commercial invoice, packing list, certificate of origin, test reports)
Shipping logistics (standard wooden drums, container loading plans, weight distribution)
Local standard compliance (BS, IEC, NFC, SANS — we produce to whatever standard your project requires)

Technical Support

Our engineering team assists with:

Cable sizing calculations for your specific project
Custom cable designs (non-standard conductor sizes, special sheath colours, LSZH requirements)
Installation guidance and bending radius calculations
Test report interpretation and compliance documentation

Frequently Asked Questions

What is the difference between 4 core and 3+1 core armoured cable?

A true 4 core cable has four conductors of equal cross-sectional area. A 3+1 core cable (also called 3.5 core) has three full-size phase conductors plus a reduced neutral conductor (typically 50% of phase conductor area). The 3+1 configuration is used when neutral current is expected to be low — for example, balanced three-phase motor loads. For general distribution where neutral current may be significant (single-phase loads connected between phases and neutral), use full 4 core.

Can I use the SWA armour as an earth conductor?

Yes, in many jurisdictions (including under BS 7671 in the UK), the steel wire armour can serve as the circuit protective conductor (CPC) provided its cross-sectional area is adequate for the expected earth fault current. The armour must be properly terminated using brass cable glands at both ends to maintain earth continuity. For STA cables, the tape armour generally has insufficient cross-section to serve as sole CPC — a separate earth conductor is recommended.

What is the minimum bending radius for 4 core SWA cable?

Per IEC 60502-1 and BS 5467, the minimum bending radius for multicore armoured cables is 6× the overall cable diameter during installation (8× for single-core armoured). For example, a 4×95mm² cable with 42.5mm overall diameter has a minimum bend radius of 255mm (approximately 510mm diameter). During fixed installation (no further movement), 4× diameter is acceptable.

How deep should 4 core armoured cable be buried?

Standard burial depths per BS 7671 and IEC 60364:

Under roads/driveways: 600mm minimum
In gardens/fields: 500mm minimum
Under building foundations: Not recommended without ducting
Lay cable on 50mm of fine sand, cover with 50mm sand, then place cable marker tape 150mm above

The cable's steel armour provides mechanical protection, but depth provides additional safety margin against spade/excavator damage.

What size 4 core armoured cable do I need for 100A three-phase supply?

For a 100A three-phase supply, you need a cable with current rating ≥100A after applying derating factors. Looking at the current rating table:

Direct buried: 35mm² (115A) is marginal — go to 50mm² (135A) for adequate margin
Clipped in air: 25mm² (124A) works but has minimal headroom — 35mm² (154A) is safer
Always apply grouping and ambient temperature factors to confirm

What is the maximum operating temperature?

XLPE insulated (standard): 90°C continuous, 250°C short-circuit (5 seconds)
PVC insulated: 70°C continuous, 160°C short-circuit

XLPE allows approximately 20% higher current rating than PVC for the same conductor size due to the higher operating temperature limit.

How do I calculate cable weight for shipping?

Use our weight table above and multiply by the length in km. Add approximately 8-12% for the wooden cable drum weight. For example:

1,000m of 4×95mm² SWA = 5,750 kg cable + ~600 kg drum ≈ 6,350 kg total
Standard 20ft container capacity: approximately 20-22 tonnes
Standard 40ft container capacity: approximately 25-27 tonnes (volume limited for smaller sizes)

Do you supply aluminium conductor 4 core armoured cable?

Yes. We manufacture aluminium conductor armoured cables from 10mm² upward. Aluminium 4 core cables are popular for utility distribution and long-run industrial feeders where weight and cost savings are priorities. Available in both SWA and STA configurations, manufactured to the same IEC 60502-1 / BS 5467 standards as our copper range.

Request a Quote

Need pricing for your project? Provide the following details and our team will respond within 24 hours with a competitive FOB quotation:

Conductor size(s) and material (copper/aluminium)
Number of cores
Voltage rating
Required standard (IEC/BS/NFC/other)
Quantity (metres or km)
Delivery destination

We supply 4 core armoured cable in all standard sizes from 1.5mm² to 800mm², in both SWA and STA configurations, with copper or aluminium conductors. Custom requirements — including special sheath colours, LSZH variants, and non-standard conductor sizes — are available on request.

Contact us for factory direct pricing →