---
title: "Cable and wire — which one for which job"
description: "7 answers on choosing the right cable and wire for the material, with the reason behind each and what fails."
url: https://atoneplace.net/which/wire/
site: "At One Place"
---

# Cable and wire

7 materials and what works on each.

| For | Use | First alternative |
| --- | --- | --- |
| Extension leads | One with a conductor rated for the full load, and always fully unwound — a coiled cable reel can be derated to a fraction of its rating. | Heavy-duty lead with a large conductor |
| A socket circuit | Typically 2.5 mm² for a UK ring final on a 32 A device, or 12 AWG on a US 20 A branch circuit — subject to the code and the installation method. | 4.0 mm² radial (UK) |
| 12 V DC and automotive | Size it for voltage drop, not current — at 12 V a small drop is a large percentage, so the cable is far thicker than the amps suggest. | Crimped terminals |
| A lighting circuit | Typically 1.0 or 1.5 mm² twin and earth in the UK, or 14 AWG on a 15 A circuit in the US — but the code and the installation method decide. | 1.5 mm² twin and earth (UK) |
| Outdoor and buried runs | Steel wire armoured cable, or a direct-burial type, at the required depth with RCD or GFCI protection — never ordinary indoor cable. | Direct-burial cable (UF in North America) |
| An electric shower | Commonly 6 or 10 mm² depending on the shower rating, the run length and the installation method — and it is notifiable work in most jurisdictions. | 10.0 mm² twin and earth |
| Speakers | 16 AWG for short runs and 14 AWG beyond about 15 metres or into low-impedance speakers — and make sure it is copper, not copper-clad aluminium. | 14 AWG (2.5 mm²) copper |

- [Which extension lead should I use for a heavy load?](https://atoneplace.net/which/wire-extension-lead/) — One with a conductor rated for the full load, and always fully unwound — a coiled cable reel can be derated to a fraction of its rating.
- [Which cable size is used for socket circuits?](https://atoneplace.net/which/wire-socket-circuit/) — Typically 2.5 mm² for a UK ring final on a 32 A device, or 12 AWG on a US 20 A branch circuit — subject to the code and the installation method.
- [Which wire size should I use for a 12 V circuit?](https://atoneplace.net/which/wire-12v-dc/) — Size it for voltage drop, not current — at 12 V a small drop is a large percentage, so the cable is far thicker than the amps suggest.
- [Which cable size is used for a lighting circuit?](https://atoneplace.net/which/wire-lighting-circuit/) — Typically 1.0 or 1.5 mm² twin and earth in the UK, or 14 AWG on a 15 A circuit in the US — but the code and the installation method decide.
- [Which cable should I use outdoors or underground?](https://atoneplace.net/which/wire-outdoor/) — Steel wire armoured cable, or a direct-burial type, at the required depth with RCD or GFCI protection — never ordinary indoor cable.
- [Which cable size does an electric shower need?](https://atoneplace.net/which/wire-electric-shower/) — Commonly 6 or 10 mm² depending on the shower rating, the run length and the installation method — and it is notifiable work in most jurisdictions.
- [Which speaker cable should I use?](https://atoneplace.net/which/wire-speaker/) — 16 AWG for short runs and 14 AWG beyond about 15 metres or into low-impedance speakers — and make sure it is copper, not copper-clad aluminium.