4.2.3 Domestic uses and safety

What type of supply is mains electricity?

Alternating current

What is the domestic electricity supply in the UK?

50Hz, 230V

Where does AC come from and how does it vary?

The mains and it varies from positive to negative as charge changes direction

What is direct current (DC)?

The movement of charge in one direction only

What supplies direct current?

Cells and batteries

What are the three wires in a plug?

Live, neutral, earth

What colour is the live wire?

Brown

What does the live wire do?

It carries the alternating potential difference from the supply

Why might the live wire be dangerous even if the mains circuit is off?

Current may still be flowing through it

What colour is the neutral wire?

Blue

What does the neutral wire do?

It completes the circuit

What colour is the earth wire?

Green and yellow

When does the earth wire carry a current?

If there’s a fault

What happens if the live wire touches the metal casing of an appliance?

It will become live and you will get an electric shock if you touch it as current flows through you to the ground