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Wire Math

Guide

SWG vs AWG vs Metric in UK Projects

A clear comparison of legacy SWG, imported AWG, and modern metric mm² for UK drawings, buying, and communication.

Overview

Use SWG and AWG to interpret source information, but normalise to mm² for UK technical decisions. This keeps selection and communication aligned across design, install, and procurement.

Three Systems, Different Purposes

SWG appears in legacy UK documentation and restoration work. AWG appears on imported parts and international product sheets. Metric mm² is the standard base for modern UK cable sizing.

The scales are not interchangeable by label. A gauge number from one system does not imply the same conductor area in another.

How to Avoid Costly Mix-Ups

Confirm the source standard first: SWG and AWG can look similar at a glance, especially on old notes, hand labels, and supplier descriptions.

Convert to mm² early in the process so the final decision, quote, and handover all use one consistent unit set.

Typical UK Site Scenario

On retrofit or maintenance visits, legacy SWG references may still appear in older records. Keep SWG for identification, then convert and document in mm² before ordering replacement cable.

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References