Quick Guide to Earthing System
The earthing provides the necessary reference of zero potential & helps in activating the operation of the circuit breaker provided for the safe disconnection of power in the event of an abnormality in the flow of current.
Earthing is an essential part of any electrical installation, essential for the safety from electrical shock, fire & for operation of most of the protective systems. apart from addressing safety from shock & fire, it' s help in limiting the interference between one appliance & the other.
The earthing system particular importance in electrical/electronic gadgets; greater dependence on voice & data communication systems, proper & effective earthing or grounding is very important.
Earthing is also necessary for diverting the effects of lightning strikes from the buildings & it's contents, including from sensitive equipment.
Type Of Earthing System:
TN System: Have one point directly earthed, the exposed-conductive-parts of the installation being connected to that point by protective conductors. There are distinct types of TN Systems in relation to the arrangement of neutral and protective conductors.
o TN-S System: Throughout the system, a separate protective conductor is used.
o TN-C-S system: Neutral & protective functions are combined in a single conductor in a part of the system. o TN-C system: Neutral & protective functions are combined in a single conductor throughout the system.
TT System: Has one point directly earthed, the exposed conductive-parts of the installation being connected to earth electrodes electrically.
IT System: Has all live parts isolated from earth or one point connected to earth through an impedance, the exposed-conductive-parts of the electrical installation being earthed.
Below table shows the numbers of earth pits & earthing requirement as per the equipment selection:
Component Of Earthing System
Earth electrode: It can be one vertical rod/ pipe/ buried plate or an earth mat with several vertical installations or a ring earthing with vertical installations.
Earthing Strip/ conductor / wire: The process of transferring the immediate discharge of the electrical energy directly to the earth by the help of the low resistance wire.
Earth bar: Located on the main switchboard for small installation. Installed in the wall / room in case of large industrial electronic installations for the connection of the main earthing wire, protective earthing wires and / or bonding wires.
Earthing Chamber: Is installed in the ground & over time the gaps between the cover & the chamber are eventually filled with dirt, sand & soils.
Earthing Compound: Is a highly hygroscopic grades of Bentonite Powder. It can be used as backfill material to maintain moisture levels in areas of dry & rocky terrain.