Electricity
Mains Electricity
To explain how UK mains electricity works and how fuses, earth wires and insulation help keep people safe.
What you will learn
What the live, neutral and earth wires do
The colours used for mains wiring in the UK
Why the live wire can be dangerous
How a fuse and earth wire improve safety
Why some appliances use double insulation
Explanation
The UK mains supply is alternating, about 230 V and 50 Hz; a cell supplies direct p.d. Live is brown, neutral blue and earth green/yellow; an earth wire normally carries no current. A fault can make a metal case live; earthing gives a low-resistance fault path so a fuse disconnects the live supply. Double insulation provides an alternative. Example: State the UK mains frequency. 50 Hz. Distinguish the observation from the explanation, and support any judgement with evidence. Justify your answer.