Mains Electricity

• • Mains Electricity
  • Mains electricity is the electricity generated by power stations and transported around the country through the National Grid
  • Everyone connects to the mains when plugging in an appliance such as a phone charger or kettle
  • Mains electricity is an alternating current (a.c.) supply
  • In the UK, the domestic electricity supply has a frequency of 50 Hz and a potential difference of about 230 V
  • A frequency of 50 Hz means the direction of the current changes back and forth 50 times every second
• • Mains Electricity
  • Mains electricity, being an alternating current, does not have positive and negative sides to the power source
  • The equivalent to positive and negative are called live and neutral and these form either end of the electrical circuit
• The live and neutral wires deliver the electricity to the device. The Earth wire is purely for safety

  
• Live, Neutral & Earth Wires

  • All electrical appliances are connected to the mains using at least a live wire and a neutral wire
  • In the UK, most electrical appliances are connected to the mains using a three-core cable consisting of
  • A live wire
  • A neutral wire
  • An Earth wire
  • The insulation covering each wire is colour coded for easy identification:
  • Live wire – brown
  • Neutral wire – blue
  • Earth wire – green and yellow stripes
• A diagram showing the three wires going to a mains powered appliance: Live, Neutral and Earth

  • The three wires have distinct purposes

  
• The Live Wire

  • The live wire:Carries the alternating potential difference from the supply to a circuit
  • It is the most dangerous of the three wires
  • If it touches the appliance without the Earth wire, it can cause electrocution

  The Neutral Wire

  • The neutral wire:Forms the opposite end of the circuit to the live wire to complete the circuit
  • Because of its lower voltage, it is much less dangerous than the live wire
• The Earth Wire

  • The earth wire:Acts as a safety wire to stop the appliance from becoming live
  • This prevents electric shocks from occurring if the appliance malfunctions or the live wire breaks off and touches the case of the plug
  • Every country has a slightly different configuration, with many using two-pin plugs and plug sockets such as in the USA and mainland Europe
  • The earth wire is still present in the two-pin plugs, just more hidden