The cable from the appliance usually consist of three wires. The wires are made of copper surrounded by a plastic sheath. The sheath is made of plastic and is coloured:
The live wire is brown
The neutral wire is blue
The earth wire is green and yellow
The live and neutral wires carry the current around the circuit. Mains current is A.C. (alternating current); this means that it is going backward and forwards in cycles (clockwise and anticlockwise around the circuit). The frequency of the cycle is 50 hertz (50 times per second). This cycling of current is achieved by varying the voltage on the live wire from about +325V to -325V and back again. The effective value of the voltage - also known the RMS value - is about 230V. The voltage on the neutral wire does not vary. It stays close to zero (hence the term neutral). In contrast the voltage of a battery does not cycle. It stays constant. This is known as D.C. (Direct Current.). Live wires have a brown insulation, and neutral wires have a blue insulation/covering.