Details of earthing system in building construction
In electricity supply systems, an earthing system or grounding system is circuitry that attaches the segments of the electric circuit with the ground and determines the electric potential of the conductors corresponding to the earth’s conductive surface.
Earthing System: Regulations for earthing system differ significantly between several segments of electric systems. Most low voltage systems attach one supply conductor to the earth (ground).
An earthing system is primarily applied for the following applications :-
1. To safeguard a structure from lighting strike, operating the lighting via the earthing system and into the ground rod in spite of moving through the structure.
2. It is a vital part of the safety system of mains electricity that resolves issues related to floating ground and sky voltage.
3. The most general ground plane for large monopole antenna and some other types of radio antenna.
Usages of earthing:
1. Safeguard human from lighting and earth fault situation.
2. Safeguard the premises from lighting and earth fault situation.
3. Offer low resistance and safe path for lighting and fault current.
4. All metallic enclosure and extraneous conductive parts remain at equipotential.
5. LV system earth
Functions of earthing:
1. Equipment earth – Path for fault current, reduce touch voltage, safeguard from electric shock.
2. Lighting earth – Low resistance path to disparate the current under lighting attack.
3. Telecom earth – Signal earth, minimize noise and interference, stable DC supply voltage and resist electric shock.
4. Computer earth – Minimize interference, retain supply voltage.
Two Classes Of Protection:
Class I protection – Application of barrier/insulation and connection of defending conductor to equipment metallic enclosure to give protection from electric shock.
Class II protection – Apart from basic insulation, supplementary layer of insulation should be provided to the enclosure. So, no irrelevant conductive part exists. The supplementary layer is not dependent on the basic insulation in order that under failing of basic insulation, it provides extra protection.
The following types of earthing are commonly found :-
a. Supply System – Neutral Earth
b. System Earth
c. Electrical Safety Earth
d. Lightning Earth
e. Generator Earth
f. Protection Earth (i.e. surge arrestor)
g. Telecom/computer earth
h. Shielding earth
i. Integrated earthing system (advocated)
j. Electrostatic earth (clean room/hospital)