Understanding Earthing & Grounding.

What is earthing, and how it differs from grounding..

Earthing is a preventive measure while Grounding is just a return path.

Earth is used for the safety of the human body in fault conditions while Grounding

(As neutral earth) is used for the protection of equipment

Ground or earth in a mains electrical wiring system is a conductor that provides
a low impedance path to the earth to prevent hazardous voltages from
appearing on equipment. Earthing is more commonly used in Britain,
European and most of the commonwealth countries standards (IEC IS),
while Grounding is the word used in North American standards (NEC, IEEE, ANSI, UL)...
Grounding means connecting the live part (it means the part which carries
current under normal condition) to the earth for example neutral of power transformer.
Earthing means connecting the dead part (it means the part which does not
carries current under normal condition) to the earth for example electrical iron etc.
One of the most misunderstood concepts is earthing and grounding.
We all understand that it is necessary; we need to understand that there are really
two separate things we are doing that we call grounding.

Grounding (System Earthing) Refers to Voltage Source ( Ex.Transformer)

Grounding transformers are typically used to -

• Provide a relatively low-impedance path to ground,
• thereby maintaining the system neutral at or near ground potential.
• Limit the magnitude of transient overvoltage when pre-striking ground faults occur. 
• Provide a source of ground fault current during line-to-ground faults. 
• Permit the connection of phase-to-neutral loads when desired.

Earthing (Equipment Earthing) Refers to

Electrical Loads / Equipment (Ex. Motor)

Earthing is a connection done through a metal link between the bodies of
any electrical appliance, as the case may be, to the deeper ground soil.
The metal link is normally of MS flat, CI flat, GI wire which should be
penetrated to the ground earth grid.

• Equipment earthing is based on IS: 3043-1987 Standards.
• Classification of electrical equipment IS: 9409-1980
• Important rules for safety and earthing practice is based on IE rules 1956
• Guide on effects of current passing through human body – IS:8437-1997
• Protection of buildings and structures from lightning – IS:2309-1969

Earthing and Grounding are two different simple concepts which 

people often get confused. Let me explain both of these things in simpler manner.

EARTHING:	GROUNDING:
Earthing means connecting the dead part (it means the part which does not carries current under normal condition) to the earth for example electrical equipment’s frames, enclosures, supports etc.	While grounding means connecting the live part (it means the part which carries current under normal condition) to the earth. For example neutral of power transformer.
The purpose of earthing is to minimize risk of receiving an electric shock if touching metal parts when a fault is present.	While the purpose of grounding is the protections of power system equipment and to provide an effective return path from the machine to the power source. For example grounding of neutral point of a star connected transformer
So earthing is to ensure safety or protection of electrical equipment and living being by discharging electrical energy to earth (ground).	During lightening dangerous high voltage can develop in the electrical distribution system wires. Grounding provides a safe return path around the electrical system of your house thus minimizing damage from such occurrences

In next blog we are going to discuss how electrical shock effect on human body in detail,
also importance of earthing for vibrant health.

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