Household Electricity (UK)

Quick revise

Fuses and Safety

Live wire alternates between +ve and –ve voltage

Neutral wire is always at 0V

Earth wire and fuses are there for safety

In the case of a fault (earth wire):

  • 1. live wire touches the metal case
  • 2. big current flows through earth wire
  • 3. … and into the earth

In the case of a fault (fuse):

  • 1. surge in current melts the fuses (a thin wire)
  • 2. the circuit breaks > the supply is broken

Wiring a Plug


Cost of Electricity

Electricity bills show how many units of electricity you used

1 unit = 1 kilowatt-hour (an amount of energy)

1 kilowatt-hour = amount of electrical energy used by a 1kW appliance left on for 1 hour

Cost = Power (KW) x Time (hrs) x Cost of 1kWh

Note: 1kW = 1000W, 1hr = 3600secs