Earthing System

 In the electrical supply system, the term earthing system refers to the electrical potential of the conductors which is relative to that of the conductive surface of the Earth. The option of earthing system is used for the electromagnetic compatibility and safety of the electricity supply.  Remember that the regulations for the earthing or grounding system differ significantly among several other countries. The PE or protective earth connection guarantees that all the exposed conductive surfaces as well as the electrical potential like the Earth’s surface, in order to prevent from the danger of electric current shock, if a human or animal touches the device wherein an insulation failure has occurred. Earthing system ensures that if there is any short circuit or insulation fault, a very powerful or high voltage current flows that would trigger the overcurrent protection device (circuit breaker, fuse) which automatically disconnects the electric supply.

The functional earth connection ensures the purpose other than offering protection against the electrical shock.  Contrary to the protective earth connection, the functional earth connection might carry current during the normal function of the device.  The functional earth connection might be essential for the devices such as surge suppression filters, electromagnetic interference, some kinds of antennas and several other measurement instruments and devices. Usually the protective earth connection is also used as the functional earth since it needs care in some circumstances of conditions.

International standard IEC 60364 differentiates three types of earthing arrangements by using the two letter codes such as IT, TT and TN.

The first letter of the code signifies the connection between the power-supply equipment and earth.

The second letter of the code signifies the connection between the earth and the device being supplied.

Questionnaire:

• What is earthing system?
• Explain more about the earthing supply system.