🧰 About this Calculator

This SWA Cable Calculator helps electricians, engineers, and contractors quickly select the minimum compliant size of steel wire armoured (SWA) cable for low-voltage installations.

• Checks your input load, run length, installation method, and grouping factor

• Suggests the smallest compliant SWA size based on typical UK wiring regulations (BS 7671)

• Uses reference values for 3-core copper SWA cables

• Considers installation methods: Clipped Direct / On Tray, Buried in Duct, Direct in Ground

• Factors in grouping (derating) and voltage drop for the actual installation route

• Shows whether the recommended cable passes both current-carrying and voltage drop requirements

• For guidance and educational purposes only

⚠️ Disclaimer

This calculator is for guidance only and is not a substitute for professional design or the IET Wiring Regulations (BS 7671).

• Results are based on standard data and typical assumptions

• Always verify final cable choices with the latest Wiring Regulations, cable manufacturer’s data, and the specific requirements of your project

• Values may vary depending on site conditions and manufacturer specifications

• For critical or high-risk installations, consult a qualified electrical designer

• The author(s) accept no liability for any loss, damage, or injury arising from use of this tool