2.3 domestic uses and safety

a.c stands for

alternating current

d.c stands for

direct current

what type of current is mains electricity

a.c

alternating current is

a current that is continuously changing direction at a specific frequency

direct current is

one directional current flow

what is the frequency of UK mains electricity supply

50Hz

what is the voltage of UK mains electricity supply

230V

what are the wires that usually connect appliances to the mains

live wire, neutral wire, earth wire

the insulation colour on the earth wire is

green and yellow stripes

the insulation colour on the live wire is

brown

insulation colour on the neutral wire is

blue

the earth wire doesn’t carry a current because

under normal circumstances there will be not current in the wire, so in case of a fault in an appliance (such as a surge or casing becoming live) current will flow to the ground

the neutral wire has a potential of

0V

the voltage between live and earth wires is

230V

the purpose of the neutral wire is

to complete the circuit by connecting the appliance back to the mains supply

in metal appliances, the earth wire is connected to

the metal casing of the appliance so if the live wire becomes loose and touches the casing the current will flow through the earth wire preventing electrocution