Earthing:
Earthing means connecting the dead part,
which does not carries current under normal condition to Earth.
The purpose of Earthing is to minimize risk of receiving an
electric shock if touching metal parts when a fault is present.
Generally GREEN
wire is used for this as a nomenclature.
Grounding:
Grounding means connecting the live part
which carries current under normal condition to the earth for example neutral
of power transformer. It is an an effective return path from the machine to the power
source.
Grounding is nothing but neutral point of a star connected transformer.
Generally BLACK wire is used for this as a nomenclature.
Difference between earthing & Grounding:
There is no major difference between earthing and Grounding,
both means “Connecting an electrical circuit or device to the Earth”. This
serves various purposes like to drain away unwanted currents, to provide a
reference voltage for circuits needing one, to lead lightning away from
delicate equipment.
(1) Difference in Terminology:
In USA term Grounding is used but in UK term Earthing is
used.
(2) Balancing the Load Vs Safety:
Grounding is done to
balance unbalanced load. While earthing is used between the equipment and earth
pit so as to avoid electrical shock and equipment damage.
(3) Equipment Protection Vs Human Safety:
Earthing is to protect the circuit elements whenever high
voltage is passed by thunders or by any other sources while Grounding is the
common point in the circuit to maintain the voltage levels.
(4) System Zero Potential Vs Circuit Zero Potential:
Earthing and Grounding both is refer to zero potential but
the system connected to zero potential is differ than Equipment connected to
zero potential .If a neutral point of a generator or transformer is connected
to zero potential then it is known as grounding. At the same time if the body
of the transformer or generator is connected to zero potential then it is known
as earthing.
