Answer / farooq, nafees, hunjra, haral

For residential & small commercial buildings, Earth
resistance(E.R) should below 25 OHms(acceptable).
While, for industrial installations, It should below 1 Ohm
ideally, however, below 5 Ohms are also acceptable.

Answer / mrinmoy boruah

Earth is a large mass and its potential is zero (neither
positive nor negative). When a matter of positive or
negative potential comes in touch with earth it gets
neutralised by supply or absorption of electrons by the
earth. Thus earth is a neutraliser.

An earth conductor connected to a buried earth pipe/plate
acts as carrier of the neutralising electrons. All of this
happens through the soil in contact with the earth pipe/plate.

Similar to current flow through a conductor there is gradual
dissipation of voltage from earthing terminal point(source)
to large mass of earth(Sink) through the soil in contact
with the earthing pipe/plate. There is gradual potential
drop acroos this surrounding soil.

Resistance of this surrounding soil to flow of current is
called as soil resistivity. Lower the resistivity of soil
lower will be the earth resistance and providing better
earthing i.e better drain point of risky high voltage.

Answer / akash

The resistance used for grounding a neutral point to earth
is called earth resistance......

Answer / brd ganesh

The resistive value of earth conductor(or earth
grid) is known as a earth resistence. It can be
mesure by using ohm meter

Answer / maktec66

The Capacity to withstand the overvoltage or capacity upto the
earth withstands its insulation property

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