Industrial, Mining & Control Cables /Steel Wire Armoured

Steel Wire Armoured Cable (SWA) — IEC 60502-1 Galvanized Steel Wire Armoured XLPE/PVC Insulated 0.6/1 kV Power Cable with Maximum Tensile Strength, Rodent Protection, and Direct Burial Capability for Underground, Industrial, Outdoor, and Heavy-Duty Power Distribution Applications

Name: Steel Wire Armoured Cable (SWA) — IEC 60502-1 Galvanized Steel Wire Armoured XLPE/PVC Insulated 0.6/1 kV Power Cable with Maximum Tensile Strength, Rodent Protection, and Direct Burial Capability for Underground, Industrial, Outdoor, and Heavy-Duty Power Distribution Applications
Brand: Yichi Cable
SKU: steel-wire-armoured-cable-swa

Steel wire armoured cable SWA: IEC 60502-1, galvanized steel wire armour, XLPE or PVC insulated, 0.6/1 kV. Copper or aluminum 1.5–630 mm², 1–5 cores. Maximum tensile strength, rodent-proof, direct burial rated. PE or PVC sheath. For underground power, industrial, outdoor distribution. CE, RoHS.

Key Features

Galvanized steel wire armour (SWA) per IEC 60502-1 — the definitive mechanical protection for power cables; round or shaped galvanized steel wires applied helically over the cable bedding layer, providing maximum tensile strength, crush resistance, and the most effective rodent protection of any cable armour type

Maximum tensile strength of any LV cable armour type — SWA's individual steel wires (1.25–5.0 mm diameter depending on cable size) carry the tensile load from ground settlement, cable pulling during installation, and the weight of the cable in vertical riser installations; the copper conductors carry zero tension — all tensile load is transferred to the armour

Rodent-proof — rodents (rats, mice, squirrels, gophers, moles) cannot gnaw through SWA: the steel wires present a circular cross-section that rotates under the rodent's teeth, preventing purchase, and the wire diameter (≥1.25 mm) exceeds the tooth penetration capability of any rodent species found in cable-damaging environments

Superior earth fault current path — the large galvanized steel cross-section of the SWA (typically 15–60 mm² steel equivalent depending on cable size) provides a low-resistance earth continuity path; the armour serves as the circuit protective conductor (CPC) in most standard armoured cable installations, eliminating the need for a separate copper earth core

Direct burial rated — SWA cable can be laid directly in a cable trench with sand bedding, without conduit; the steel wire armour protects against the mechanical hazards of direct burial: stones and rock fragments in the backfill, ground settlement and movement, and accidental excavation by hand tools (a spade will strike the steel wires before reaching the conductors)

Crush and impact resistant — the helical steel wires distribute a crush or impact load across multiple wire contact points; the wire diameter and lay angle are specified by IEC 60502-1 to provide the crush resistance for the cable to survive the weight of backfill soil, vehicle traffic above a buried cable route, and accidental impact from construction and industrial activity

XLPE (90°C) or PVC (70°C) core insulation — XLPE for the higher current-carrying capacity and superior water treeing resistance required for buried installations with groundwater exposure; PVC for cost-sensitive indoor and ducted installations

Flexibility in large sizes — SWA retains more flexibility than STA (steel tape armour) at larger cable diameters because the individual steel wires can slide relative to each other during bending, whereas the continuous steel tapes of STA would wrinkle and kink at the inside of the bend

Applications

Direct burial underground power distribution — SWA cable laid directly in a cable trench with sand bedding, cable protection tiles, and warning tape; the primary cable for underground LV power distribution between buildings, to street lighting, to external plant equipment, and for campus-wide buried power networksUnderground duct and conduit pulling — SWA cable pulled through buried ducts and conduits; the SWA provides the tensile strength to pull the cable through the duct, and the smooth helical wires slide more easily through the duct than the continuous tape surface of STAOutdoor cable tray and ladder rack — SWA cable for outdoor above-ground cable management in industrial plants, water and wastewater treatment works, and power stations where the cable is exposed to weather, UV, and the risk of mechanical impact from plant operations and maintenance activitiesIndustrial plant power distribution — SWA cable for factory and process plant LV distribution where the cable is clipped to building steelwork, run in cable tray, or buried in the plant floor; the SWA protects against the mechanical hazards of the industrial environment: forklift impact, dropped tools, vibration from machinery, and contact with plant equipmentVertical riser installation — SWA cable for building vertical riser shafts from the basement substation to upper-floor distribution boards; the SWA's tensile strength supports the cable's own weight in the vertical run, and the steel wires provide intermediate support at each cable cleatAgricultural and rural power supply — SWA cable for buried power to farm buildings, irrigation pumps, grain dryers, and rural workshops; the buried cable crosses fields subject to ploughing, livestock trampling, and agricultural vehicle traffic — the SWA provides the mechanical protection that enables the cable to survive in this environmentTemporary construction site power — SWA cable for temporary site power distribution where the cable is laid on the ground, in shallow trenches, or across site roadways; the SWA protects against construction vehicle traffic, site plant, and the general mechanical abuse of the construction environment

Technical Specifications

Standard — Cable	IEC 60502-1 (Power cables with extruded insulation for rated voltages 0.6/1 kV — including SWA construction); BS 5467 (UK standard for armoured power cables — SWA with XLPE insulation, PVC sheath); BS 6346 (PVC insulated SWA); the standards define the armour wire diameter, lay length, bedding and sheath thickness, and test requirements
Rated Voltage (U₀/U)	0.6/1 kV (Um = 1.2 kV)
Conductor Material — Copper	Bare copper; IEC 60228 Class 2 stranded (circular or compacted); 1.5–630 mm²
Conductor Material — Aluminum	Aluminum (99.5%); IEC 60228 Class 2; 16–630 mm²
Core Configuration	Single-core; 2-core; 3-core; 3.5-core; 4-core; 5-core
Core Insulation — XLPE (Standard)	Cross-linked polyethylene; 90°C continuous; 250°C short-circuit; preferred for buried and outdoor SWA because of water treeing resistance and higher current capacity per cross-section
Core Insulation — PVC (Alternative)	PVC type A; 70°C continuous; 160°C short-circuit; for cost-sensitive indoor and ducted installations
Core Identification — Multi-Core	Per HD 308 S2: brown (L1), black (L2), grey (L3), blue (N), green-yellow (PE, if included as a separate core)
Core Assembly	Concentric stranding of insulated cores with non-hygroscopic PP filler elements to produce a circular cross-section for the bedding and armour layers; the filler ensures the inner covering (bedding) is applied to a smooth cylindrical surface, which in turn ensures the armour wires are laid at a constant helix angle and tension
Binder Tape	Polyester or PP tape wrap over the core assembly; secures the cores and fillers in position during the bedding extrusion
Inner Covering (Bedding) — PVC ST2	Extruded PVC type ST2; the bedding is a continuous cylindrical layer that the armour wires are laid onto; the bedding thickness is calculated per IEC 60502-1 to allow approximately 10–15% of the armour wire diameter to embed into the bedding under tension, which locks the wires in position and prevents them from shifting during cable bending
Armour — SWA (Steel Wire Armour)	Galvanized steel wires applied helically; wire diameter per IEC 60502-1 Table 5: 1.25 mm (smallest cables) to 5.0 mm (largest cables); the wire diameter increases with cable diameter to maintain a consistent ratio of armour wire to cable OD for uniform mechanical protection across the cross-section range
Armour Wire — Galvanizing	Zinc coating per BS EN 10244-2 (class A or class B); the zinc coating provides corrosion protection for the steel wires in buried and outdoor service; typical zinc coating weight 200–300 g/m² depending on wire diameter — the coating thickness is designed for 30+ year buried service life
Armour — Lay Length	Typically 10–14× the diameter over the bedding; the lay length is a compromise between flexibility (shorter lay = more flexible) and armour coverage (longer lay = fewer gaps between wires); the standard lay length provides a balance of flexibility and mechanical protection
Armour — Single-Core SWA AC Consideration	Single-core SWA cables carrying AC current MUST be installed with non-magnetic cable glands (brass, aluminum, or non-magnetic stainless steel) and the gland mounting plate must also be non-magnetic. The alternating magnetic field around the single conductor induces eddy currents in the magnetic steel armour and gland, causing heating that can damage the cable sheath at the gland entry. For single-core AC circuits, aluminum wire armour (AWA) is electrically preferred over SWA because aluminum is non-magnetic
Armour — Earth Continuity	The SWA serves as the circuit protective conductor (CPC). The armour DC resistance (Ω/km) is published in the cable data sheet. The designer must calculate the earth fault loop impedance Z_s and verify that the armour cross-section meets the adiabatic requirement: A_steel ≥ √(I²t) / K where K = 46 for steel at 200°C final temperature. If the armour CSA is insufficient, a separate copper earth core must be included
Outer Sheath — PVC ST2	Extruded PVC type ST2; black RAL 9005; UV-stabilized; standard for general purpose SWA cable
Outer Sheath — PE ST7	Extruded PE type ST7; black; enhanced moisture resistance and UV stability; recommended for direct burial SWA cable — PE is a better moisture barrier than PVC over the 30+ year buried service life
Maximum DC Conductor Resistance at 20°C — Copper	Per IEC 60228 Class 2; 12.1 Ω/km (1.5 mm²) to 0.0283 Ω/km (630 mm²)
Maximum DC Conductor Resistance at 20°C — Aluminum	1.91 Ω/km (16 mm²) to 0.0469 Ω/km (630 mm²)
Insulation Resistance at 20°C — XLPE	≥1 000 MΩ·km; PVC: ≥36.8 MΩ·km
Test Voltage (AC — Routine)	3 500 V AC / 5 min (core-to-core, core-to-armour)
Temperature — Continuous (XLPE)	90°C conductor; PVC sheath surface: 70°C; PE sheath surface: 80°C
Temperature — Installation (PVC Sheath)	0°C minimum without pre-heating
Temperature — Installation (PE Sheath)	-20°C minimum
Minimum Bending Radius — Multi-Core SWA	15× cable OD (the SWA limits the bend radius because the armour wires on the inside of the bend must compress and those on the outside must extend; the 15× OD radius ensures the wires do not buckle or separate at the bend)
Maximum Pulling Tension	50 N/mm² total copper conductor cross-section; 30 N/mm² aluminum; pull by conductor using a pulling stocking over the outer sheath — pulling by the armour alone can stretch the armour wires, permanently increasing the armour lay length and reducing its mechanical protection
Current Rating (Typical, Copper/XLPE/SWA/PVC, 4-Core, Buried Direct, 20°C Soil)	16 mm² = 88 A; 35 mm² = 135 A; 70 mm² = 200 A; 120 mm² = 272 A; 240 mm² = 408 A; de-rate for soil thermal resistivity (typical 1.2–2.5 K·m/W), burial depth, and cable grouping
Short-Circuit Temperature — XLPE	250°C (max 5 s); PVC: 160°C (max 5 s)
Flame Retardant — PVC Sheath	IEC 60332-1-2
Certifications	CE; RoHS; BASEC (UK, BS 5467) on request; KEMA KEUR on request; VDE on request; ISO 9001 manufactured

Detailed Description

What Is Steel Wire Armoured (SWA) Cable?

Steel Wire Armoured (SWA) cable is a power cable with a helical layer of galvanized steel wires applied over the insulated core assembly, providing the maximum mechanical protection available in a low voltage cable construction. SWA is the cable that goes underground — the cable that an electrician buries in a trench to supply a detached garage, a garden office, a street lighting column, or a factory sub-distribution board. It is the most widely used armoured cable in the world, defined by IEC 60502-1 and specified wherever a power cable leaves the protected indoor environment and enters the world of soil, water, vehicles, rodents, and accidental damage.

The steel wire armour is not simply "added protection" — it defines the cable and how it must be installed, terminated, and integrated into the electrical system. The armour serves as the circuit's earth continuity path. The armour must be terminated with armoured cable glands that grip the steel wires and provide the earth connection to the metal enclosure. And the armour must be sized — by the cable designer, per the adiabatic equation — to carry the prospective earth fault current for the time required for the protective device to clear the fault.

SWA vs No Armour — When Armouring Is Mandatory

Installation Condition	Unarmoured Cable	SWA Cable
Indoor cable tray, no mechanical risk	Suitable	Acceptable (over-specified but safe)
Indoor surface-mounted, risk of impact	Not suitable	Required
Outdoor clipped to wall	Not suitable (UV degrades PVC sheath, no mechanical protection)	Required
Buried directly in soil	Not permitted (no crush or rodent protection)	Required — with PE sheath recommended
Buried in duct	Acceptable for plastic ducts in sand bedding	Required for duct pulling (tensile strength) and for ducts under roadways (crush protection)
Cable crossing under roadway	Not permitted	Required — minimum 1 000 mm burial depth
Industrial plant floor	Not suitable (forklift, dropped tools, vibration)	Required
Agricultural land	Not suitable (ploughing, livestock, rodent damage)	Required
Building riser shaft (vertical)	Requires separate catenary wire support	SWA carries its own weight — tensile armour used as catenary

The rule of thumb for cable specification: if the cable is indoors, in a cable tray, in a clean and protected environment, and the installation method provides all necessary mechanical protection — unarmoured cable may be acceptable. For any other installation condition — outdoors, underground, industrial, agricultural, or any location with risk of mechanical damage — SWA is the minimum specification.

Why Choose Yichi SWA Cables

IEC 60502-1 / BS 5467 compliant — the definitive SWA standard: The armour wire diameter per IEC 60502-1 Table 5, the bedding and sheath thickness, the galvanizing class per BS EN 10244-2, and the complete cable construction per the standard. SWA is manufactured to the standard — not to a reduced specification for cost saving
Galvanized steel armour — verified zinc coating weight: The zinc coating on the armour wires is the corrosion protection for buried service. The coating weight is specified, measured, and verified on every armour wire batch. Underspecified zinc coating leads to armour corrosion, loss of earth continuity, and cable failure in buried service after 10–15 years — the SWA cable's design life is 30–50 years, and the armour corrosion protection must support that
PE sheath recommended for direct burial — a better moisture barrier than PVC: PE ST7 is less permeable to water vapor than PVC ST2 and does not contain plasticizers that migrate out over time. For SWA cable that will be buried in soil for 30+ years, PE sheath is the recommended specification. PVC sheath is acceptable for indoor, surface-mounted, and ducted SWA installations
Single-core SWA guidance — non-magnetic glands and AWA alternative: Our technical documentation includes clear guidance on the single-core SWA eddy current heating issue and the requirement for non-magnetic glands and gland plates. For single-core AC circuits, we offer aluminum wire armour (AWA) as the electrically preferred alternative to steel SWA
Armour earth continuity verified — resistance data published: The armour DC resistance (Ω/km) is published for every SWA cable size and core configuration. Use this data to calculate the earth fault loop impedance and verify the armour's suitability as the CPC. If the armour cannot meet the adiabatic requirement, we recommend the appropriate additional copper earth core

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Product: Steel Wire Armoured Cable (SWA) — IEC 60502-1 Galvanized Steel Wire Armoured XLPE/PVC Insulated 0.6/1 kV Power Cable with Maximum Tensile Strength, Rodent Protection, and Direct Burial Capability for Underground, Industrial, Outdoor, and Heavy-Duty Power Distribution Applications

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