Mains Electricity

The electricity we use in the home and at school is called mains, or current, electricity. Mains electricity reaches your home through a wire. This is connected to a power plant which may be very far away. Mains electricity flows through wires in a similar way to water flowing through a hose. We call this flow an electric current. Current electricity is very easy to use because it can be sent along wires to wherever it is needed. Once the electricity wire reaches your house, a set of smaller wires carries it through the walls, under the floors, and around the ceilings. Some wires carry electricity for the lights. Switches let you turn each light on and off.

Electricity enters your home through a main cable from your local sub-station, which is connected to the electricity grid, the national network of cables that link electricity power stations to local sub-stations. Mains electricity is an alternating current supply. This means that the current passing through any mains appliance repeatedly reverses its direction. The frequency of mains supplies in Britain and most other EU countries is 50 hertz. This means the current changes direction and back again 50 times every second.

Electricity in your Home:

Electricity supplied to your home passes through an electricity meter, a master switch and a distribution board. Separate circuits for heating, lighting, electric cookers and showers branch off from the distribution board. The master switch is used to disconnect the distribution board from the main cable.

Each Circuit includes:

• a live wire which alternates from positive to negative and back every cycle
• a neutral wire which stays at a voltage close to zero because it is earthed (i.e. connected to ground) at the local sub-station.

The live wire alternates between + 325 volts and -325 volts. In terms of electrical power, this is equivalent to a direct voltage of 230 volts.

Questionnaire:

• What is Mains Electricity? Explain.