# Explain why the earth wire is an important safety feature in a mains appliance that has a metal casing.

> AQA GCSE Physics (8463) — 4.2.3 Domestic uses and safety · Explain · 4 marks

## Mark scheme (4 marks)

1. The live wire may come loose and touch the metal casing, making the casing live / at 230 V
2. Without the earth wire, anyone touching the casing would receive an electric shock as current flows through them to the ground
3. The earth wire is connected to the metal casing and provides a low-resistance path to earth
4. The large current that flows through the earth wire causes the fuse to melt / blow, breaking the circuit and making the appliance safe

## Key terms

- [earth wire](https://www.gradenine.co.uk/glossary/earth-wire)

## Related

- [Revision notes for AQA GCSE Physics (8463)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-why-the-earth-wire-is-1a88127a) · Published by Druglandscape Ltd.