Medium Voltage SWA Armoured Cable: Specifications, Construction and Selection Guide

Medium voltage SWA armoured cable combines insulated power conductors with steel wire armour, providing a protected route for electrical distribution where mechanical risks or direct burial may be considerations. To select the right cable, buyers should confirm the system voltage, conductor size and material, insulation, number of cores, installation conditions, and applicable project standard. The term “medium voltage” varies by market and specification; IEC 60502-2, for example, addresses cables rated from 6 kV to 30 kV. At Zhongdong Cable, we use the project requirements—not the product name alone—as the starting point for a quotation and configuration review.

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Key Takeaways

SWA means steel wire armour, which can provide mechanical protection; it does not replace correct electrical design or suitable installation practices.
Voltage rating, cable construction, conductor size, and installation environment must be reviewed together.
For single-core cables, armour material and design require particular attention because steel is magnetic.
Share a cable schedule, applicable standard, route conditions, and delivery requirements when requesting a quotation.

Who This Guide Is For

This guide is for electrical contractors, project engineers, distributors, and procurement teams sourcing medium voltage power cables. It is also useful for buyers comparing quotations that use different descriptions for voltage class, insulation, or armour. It does not replace project engineering, local electrical regulations, or a review by the responsible design authority. Use it to prepare a clear specification and identify questions to resolve before ordering.

What Is Medium Voltage SWA Armoured Cable?

Medium voltage SWA cable is a power cable designed for medium voltage distribution, with steel wire armour incorporated into its construction. A typical design includes one or more conductors, conductor screens, insulation, insulation screen, metallic screen, bedding or inner sheath, steel wire armour, and an outer sheath. The exact arrangement varies with the cable standard, voltage rating, number of cores, and installation requirements. The armour can help resist certain external mechanical stresses, while the insulation and screens provide essential electrical functions.

Typical Cable Construction

Conductor: Usually copper or aluminium, selected according to current capacity, installation conditions, and project requirements.
Conductor screen: A semiconductive layer used in many medium voltage designs to support a uniform electric field around the conductor.
Insulation: XLPE is a common option; other materials may be specified according to the project standard and service conditions.
Insulation screen and metallic screen: These layers form part of the cable’s electrical stress-control and earthing design. Screen size and bonding arrangements need engineering review.
Bedding, armour, and outer sheath: Bedding supports the armour, while steel wires provide mechanical protection. The outer sheath protects the cable from environmental exposure specified for the installation.

For multicore designs, steel wire armour is commonly considered as part of the mechanical protection system. Single-core designs need careful review: steel is magnetic, so armour choice and construction must be compatible with the cable arrangement and the project’s electrical design. Buyers should not assume that a multicore SWA specification can simply be copied for a single-core cable.

Specifications Buyers Should Confirm

A useful cable specification identifies more than conductor size and voltage. It should state the governing standard and edition, rated voltage, number of cores, conductor material and class, insulation type, screen requirements, armour, sheath, and installation conditions. IEC 60502-2 covers extruded-insulation power cables for rated voltages from 6 kV to 30 kV, with associated equipment requirements; a project may instead specify another national or industry standard. Always confirm that the proposed cable designation and test requirements align with the actual project specification.

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Important Electrical and Installation Details

Voltage rating: Confirm the system voltage and the cable’s rated voltage designation, including the relevant standard notation.
Conductor size: Determine this through load, voltage-drop, fault-level, installation, and derating calculations—not load current alone.
Insulation and temperature: XLPE is often specified for medium voltage applications. Some XLPE cable standards permit a maximum conductor temperature of 90°C under normal operating conditions, but the applicable standard and product design must be checked.
Short-circuit duty: Confirm the required fault current and duration with the design engineer. A commonly referenced XLPE short-circuit conductor limit is 250°C for up to 5 seconds, subject to cable design and the applicable standard.
Route and environment: Identify direct burial, duct, tray, indoor or outdoor use, ambient conditions, moisture exposure, and any chemical or UV requirements.
Screen and earthing: Specify metallic screen construction, cross-section, and bonding requirements according to the system design.

Application Matching

Medium voltage SWA cable may be considered for utility distribution, industrial power networks, infrastructure projects, and installations where mechanical protection is required by the route or project specification. Suitability depends on the full cable design and installation method; “armoured” by itself does not confirm suitability for every buried, wet, corrosive, or high-impact environment. A cable installed in a duct may have different thermal and mechanical requirements from one directly buried in soil. Share the route details with the cable supplier and design team before finalizing the construction.

A Practical Selection Framework

Define the electrical system. Provide system voltage, frequency, load, fault level, and earthing arrangement, along with the required cable rating.
Describe the installation. State whether the route is direct buried, ducted, on tray, or otherwise installed, and include route length and environmental conditions.
Specify conductor and cores. Identify copper or aluminium, conductor class if required, number of cores, and any parallel-run arrangement.
Set insulation, screen, armour, and sheath requirements. Confirm the standard, screen details, armour material, sheath material, and any special requirements such as flame performance.
Check accessories and testing. Confirm compatibility with joints and terminations, drum lengths, marking, documentation, and the inspection or test requirements stated in the purchase specification.
Review the offer technically. Compare each supplier’s construction against the same specification instead of comparing price alone.

Common Selection Mistakes

One common mistake is choosing conductor size from current alone, without considering voltage drop, fault conditions, installation method, or correction factors. Another is treating the word “SWA” as proof that a cable meets a particular project standard or environmental requirement. Buyers can also overlook screen bonding, termination compatibility, single-core armour considerations, and the required drum length. Resolve these details before purchase to reduce the risk of specification gaps, installation delays, or costly changes.

Price, MOQ, and Lead-Time Considerations

There is no reliable universal price for medium voltage SWA cable because the cost depends on conductor metal and size, voltage rating, core configuration, insulation and sheath materials, armour design, order quantity, and required documentation. Minimum order quantities and production schedules also vary by construction, material availability, factory loading, and destination. Rather than relying on a generic price or delivery estimate, request a quotation against a complete technical specification and required delivery date. For budget planning, ask suppliers to state the quotation validity, quantity basis, drum length, packaging, and any inspection requirements.

Supplier Evaluation Checklist

Can the supplier provide a construction and datasheet that match the stated standard and project specification?
Are voltage rating, conductor, insulation, screen, armour, sheath, and marking clearly identified in the offer?
Can the supplier clarify single-core versus multicore armour design and compatibility with the proposed installation?
Are applicable routine tests, documentation, packaging, drum details, and inspection arrangements clearly described?
Can the supplier confirm MOQ, production lead time, shipping assumptions, and quotation validity for the requested configuration?

At Zhongdong Cable, we support B2B enquiries by reviewing the buyer’s required cable construction, project standard, quantity, and delivery destination before confirming a proposed configuration. Provide your cable schedule or specification so our team can identify open technical points and prepare a quotation for review. Final selection should remain subject to the project engineer’s approval and the applicable local requirements.

Conclusion: How to Choose the Right Medium Voltage SWA Cable

The right medium voltage SWA armoured cable is the one that matches the electrical system, installation route, mechanical protection needs, and governing specification—not simply the one with the lowest quoted price. Start by confirming voltage, conductor size and material, cores, insulation, screen, armour, sheath, and required testing. Then compare supplier offers line by line and resolve any gaps before issuing a purchase order. Send Zhongdong Cable your specification, quantity, route conditions, and target delivery date to begin a project-specific technical and commercial discussion.