in this video we're going to look at the different wires that you find in plugs and cables and also why touching the wrong one can give you an electric shock here in the uk the large majority of our electricity comes from the national grid which distributes power across the country to our homes we call the electricity that this supply's main supply and the two things to know about it are that it's an alternating current of 230 volts and it's at 50 hertz so whenever we plug electrical appliance from our home into a plug socket we're connecting it to the main supply this usually involves a three core cable which means that is a cable with three wires inside of it the live wire the neutral wire and the earth wire each of the wires are made of copper so that they can conduct electricity and they're coated in a layer of insulating plastic for safety the colour of each plastic coating though is specific to the type of wire and this helps us to identify them for the exam it's important that you know which color each of the cables are and what each of them does the live wire is brown and is the one that provides the alternating potential difference of around 230 volts from the main supply meanwhile the neutral wire is blue and acts to complete the circuit by carrying away current so effectively electricity flows into the device through the live wire and flows out through the neutral wire which has a potential difference of zero volts lastly we have the earth wire which is striped green and yellow the earth wire doesn't normally carry a current at all and has a potential difference of zero volts its role is to stop the appliance casing from becoming live which could happen if the live wire came loose and touched the casing this would mean that if we were to touch the casing we'd get a big electric shock to prevent this the earthwire provides an alternative pathway for the current to flow away so that any dangerous electricity will pass through the earth wire rather than passing through us now the reason that the electricity from the live wire is happy to pass through the neutral wire or occasionally the earth wire is that they both have potential differences of zero volts while the live wire is at 230 volts and it's this difference in voltage that causes electricity to pass from one to the other unfortunately humans also have a potential difference of zero volts and so if we touch the live wire it will cause a large current to flow through us in the form of an electric shock this is why it's so important to never touch plug sockets even if they're switched off the live wire still has a potential difference and so any contact could result in a shock anyway that's everything for this video so if you enjoyed it then do give us a like and subscribe and we'll see you soon