In a standard British three pronged plug there are three wires; the live wire, the neutral wire, and the earth wire. The earth wire is coloured green, green and white striped, or green and yellow striped. The live wire is brown, and the neutral wire is blue. In a plug the earth wire should be wired at the top of the plug, the live wire towards the right hand side of the plug (bottom right) and the neutral wire towards the bottom left of the plug (bottom left). This is easy to remember as the first two letters of the word "blue" and b and l, which could stand for "bottom left," and similarly the first two letters of the word "brown" and b and r, which could stand for "bottom right". By the process of elimination the earth wire is placed in the only remaining part of the wire, that is, the top. When wiring a British plug there are a number of safety features which one should remember. First of all, the correct fuse should always be fitted into the plug. Standard fuses are the three amp, five amp, and thirteen amp fuses. The thirteen amp fuses is for larger instruments while the five amp is the fuse for standard lighting and the three amp fuses is usually for light instruments. However this is not always the case and it is recommended that when fitting a fuse to a plug, you check to see which fuse the device attached to the plug recommends. If there is no recommended fuse, find the power rating (in Watts) for the fuse. The fuse used is then the amp just above the Wattage divided by 230 for a plug in Britian, as the mains supply is 230 Volts. Fuses are necessary for plugs because in the case of a short circuit they immediately blow as the high current melts them. This prevents any more current passing through the plug. This is good because if there was a loose connection or short circuit, and electricity was passing through the appliance, it could electricute the person operating the device and kill them. Fuses are therefore a vital safety feature in a plug. However, there are many other things to think about when wiring a plug, all of which cannot be listed here, and it is suggested that you visit this website: www.pat-testing.info/wireaplug.htm to learn how to wire a plug, or get taught the skills needed by an electrician or person with a certificate in plug wiring (which can be got by students in many high schools).
Brown - hot, blue - neutral, green - ground
The blue is "Neutral", the brown is "Hot" or "Live" and the green is "Ground".