AQA GCSE Mains Electricity

Mains Electricity

UK Mains electricity is 230 Volts, 50 Hertz and is Alternating Current (AC).

Alternating means that it will continuously change direction as shown below.

UK Electricity is 50 Hz, this means that the direction changes 50 times per second, so the generator that is producing this electricity, rotates at a rate of 50 times per second!

Different countries will use a slightly different frequency. USA uses 60Hz.

UK Mains Plugs

In the above plug 3 core cable is used, so it contains Live(brown), Neutral(blue) and Earth wire (green-yellow).

Electrical appliances with a metal case need an Earth wire. Appliances with a plastic case are said to be double insulated, they only need two core wire (live and neutral).

Role of the wires

Live wire will carry the alternating potential difference from the mains supply to the appliance. Remember it alternates at 50 times per second in UK. UK Electricity is 50 Hz.

Neutral wire will complete the circuit, it should be earthed at 0V at the local substation. In some cases the potential difference of the neutral wire is almost 0V. Without the neutral wire the circuit is incomplete, so it is needed!

Earth wire is Earthed at 0V, it should not carry a current. It will carry a current if the appliance becomes faulty. If the live wire were to break, make contact with electrical case, charges flow onto the case. So, case becomes live.