Introduction
Table of contents
Steel Wire Armoured (SWA) cable is one of the most widely used power cables in the UK. This post provides a detailed breakdown of steel wire armoured cable construction, standards, and performance requirements, with references to BS 5467, BS 6724, and BS 7671 (IET Wiring Regulations).
At Electrical4Less, we stock armoured cable from leading UK suppliers Doncaster Cables and UK Cables, ensuring full compliance with British Standards.
How Steel Wire Armoured Cable Is Constructed
SWA cable is designed to withstand mechanical stress while maintaining electrical performance. Its structure typically includes:
- Conductor – Copper (solid or stranded) for current flow.
- Insulation – PVC (BS 5467) or LSZH (BS 6724) depending on fire safety needs.
- Bedding – Separates insulated cores from the armour.
- Steel Wire Armour – Galvanised wires providing mechanical protection and, if sized correctly, serving as a circuit protective conductor (CPC).
- Outer Sheath – PVC or LSZH, giving resistance to moisture, chemicals, and UV.
For different environments, electricians can choose PVC SWA or LSZH SWA:
- PVC SWA – durable, cost-effective, suitable for general use.
- LSZH SWA – low smoke, zero halogen, used in fire-critical areas.
Standards and Compliance
Steel wire armoured cable must meet strict UK and European standards:
- BS 5467 – Armoured cables with PVC insulation and sheath.
- BS 6724 – Armoured cables with LSZH insulation and sheath.
- BS 7671 (IET Wiring Regulations) – Covers installation practices, current-carrying capacities (Appendix 4), and protection requirements.
For example:
- Regulation 522.8.10 – minimum burial depth of 450 mm in domestic applications.
- Table 4E4A (Appendix 4) – current ratings of steel wire armoured cable depending on installation method.
- Table 54.7 – requirements when using armour as a CPC.
By complying with these standards, SWA cable provides safe and reliable performance across domestic, commercial, and industrial installations.
Typical Applications
Steel wire armoured cable is trusted for:
- Underground power supplies (Underground Cables)
- Sub-main distribution circuits
- Outdoor lighting and EV charging feeds
- Industrial machinery supplies
Depending on the application, different core sizes are available:
Accessories for Safe Termination
To comply with BS 7671 Section 526 (connections), SWA cable must be terminated with suitable accessories:
- Armoured Cable Glands – ensure strain relief and safe electrical connection.
- SWA Gland Banjos – provide secure earthing bonds.
- SWA Clips – fix cables securely along walls or structures.
FAQs on Steel Wire Armoured Cable
Can the armour act as the earth?
Yes, provided it meets CPC size requirements in BS 7671 Table 54.7.
What is the maximum temperature rating?
Typically -15°C to +90°C, depending on sheath type.
Which standard applies to LSZH SWA?
BS 6724, which ensures low smoke and halogen-free performance in fire conditions.
What current can SWA carry?
Depends on size and installation method; current ratings are listed in BS 7671 Appendix 4 tables.
Do I need glands for every SWA termination?
Yes, glands ensure compliance with BS 7671 Reg 526.1 on secure connections.
Why Buy Armoured Cable from Electrical4Less
Electrical4Less supplies steel wire armoured cable directly from Doncaster Cables and UK Cables. We offer:
- PVC, LSZH, Low Smoke, and LSF variants
- Sizes from 2 Core to 7 Core in stock
- Essential accessories including armoured cable glands
Fast delivery, competitive pricing, and trade support make us a trusted wholesaler for professional electricians.
Steel Wire Armoured Cable Explained in Detail