In AC systems the two wires of a circuit alternate polarity many times per second. So positive and negative switch, half of the time a wire is positive the other it is negative.
So why is it important to connect plug sockets to the correct coloured wire? What is the difference between the live and neutral wires?
To all future readers of this question: please be aware that the assumptions and statements made by @Martin Lowe in the question are substantially wrong, and believing them could lead to considerable safety risks for you or for any others who may interact with your residential electricity.
So why are people still being told that they need to connect plug sockets to the correct coloured wire? There IS no live and neutral wire as the live and neutral switches many times per second!
This is completely false. In a correctly wired residential circuit the live and neutral wires do not switch many times per second. The neutral wire is a current carrying wire that is maintained at ground potential at all times. The ground wire is also maintained at the same potential, but normally it only carries current in the event of a fault. The live or hot wire has a voltage which alternates above and below the fixed neutral wire, the frequency and voltage varies from country to country. The roles of the neutral and the live wire are not interchangeable.
Your blue and brown wires can be connected however you want in a socket as this is NOT DC, in DC is DOES matter but in AC why the fuss?
The fuss is because we usually want to avoid injuring people or setting property on fire. Incorrect residential wiring is hazardous and connecting the wires contrary to local codes could injure you, people who touch appliances connected to your wiring, or future electricians working on the residence. Connecting the wires wrong could result in the chassis of an appliance becoming live. Do not attempt to wire any circuit inappropriately.
