The planet Earth’s top layer surface is covered with soil and rocks. This layer is usually associated with agricultural use or excavations for construction
foundations. Nonetheless it has an important electrical property, called conductivity (or low resistance) that forms an integral part of many modern day installations in industrial plants and utilities for a variety of reasons.

The Earth is a relatively poor conductor of electricity compared to conductors like copper or aluminum cables. However considering that the Earth’s mass is huge, it provides a large area for the flow of current, and thus resistance to current can be quite low with the result that the earth can be considered a good conductor.

In fact, the whole of the planet may thus be considered as an infinite conductor which is at reference (zero) potential. In Europe it is referred to ‘earth’ whilst in the USA it is called ‘ground’.

People are usually constantly in contact with earth, thus if they touch a charged object whose potential is different from earth, the resulting potential difference across the person will result in an electric shock.

The process of earthing consists of connecting together all objects that may
potentially become charged to the general mass of earth, so as to provide a path for fault currents and to create an equipotential on all objects as close as possible to the earth potential.

In short, an earthing system will

• prevent a potential difference between earth and earthed parts, hence eliminating the risk of shock and
• provide a low path resistance to fault currents thus ensuring that circuit protective systems (e.g. fuse, circuit breaker, residual circuit breaker) can operate.
  Earthing/Grounding is thus an indispensable part of an electrical system to ensure it’s safety and integrity.