# A kettle has a metal casing and is connected to the mains electricity supply using a three-core cable containing a live wire, a neutral wire, and an earth wire. A fault develops inside the kettle so that the live wire comes into contact with the metal casing. Explain how the earth wire and fuse work together to protect the user from electric shock.

> Pearson Edexcel International GCSE Physics (4PH1) — 2.1 Mains electricity · Explain · 4 marks

## Mark scheme (4 marks)

1. The earth wire provides a low resistance path for current to flow from the metal casing to earth
2. A large / surge of current flows through the earth wire
3. The large current causes the fuse wire to overheat and melt / blow
4. The circuit is broken / disconnected, so the casing is no longer live and the user cannot receive an electric shock

## Key terms

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

## Related

- [Revision notes for Pearson Edexcel International GCSE Physics (4PH1)](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/a-kettle-has-a-metal-casing-be942b80) · Published by Druglandscape Ltd.