Introduction of the three main electrical conductors

Three main electrical conductors enter a domestic property and are distributed throughout it. 

These conductors are referred to as live, neutral, and earth.

The live and neutral conductors should be considered as the 'power supply to the premises. 

The voltage between live and neutral will generally be about 230 V AC. In all normal circumstances, the current that enters the premises on the live conductor leave it neutral, and vice-versa. 

The earth conductor carries negligible current except in fault situations.

Although the live and neutral conductors both carry current, only the live conductor is at a voltage that could be harmful. 

The neutral conductor will normally be at the same voltage as the earth conductor. 

In fact, at some point, the neutral and the earth will be connected together. This situation is shown in the figure.

The figure grossly oversimplifies the real situation, of course; we don't each have an electrical power station in the garden, delivering electricity at 230 volts. 

In reality, the supplier's distribution system will be a complex mixture of power cables, transformers, and switchgear, but this need not concern us. 

In practice, we can assume that the electricity supply takes the form shown in figure 6.

Note that the supplier's equipment is connected to earth on one side, and this is what distinguishes 'life' from 'neutral'. The 'neutral' side is connected to the earth at the supplier's side. 

Your premises will also have a separate earth connection, either brought in by the electricity supplier's cable or attached to a stake driven into the ground (which is the arrangement shown in the figure above). 

The different methods of supplying earth are sometimes important, particularly when calculating whether we need more electrical shock protection than earthing alone can provide.

From the main cable entering the premises, live, neutral and earth conductors will be distributed to every electrical appliance using a variety of different cable types and sizes.