- Technical Blog From My Notebook

Thursday, February 18, 2016

Difference between earthing and grounding




Grounding is the commonly word used for earthing in the North American standards like IEEE, NEC, ANSI and UL etc while, Earthing is used in European, Common wealth countries and Britain standards like IS and IEC etc.
Ground is a source for unwanted currents and also as a return path for main current. While earthing is done not for return path but only for protection of delicate equipments. It is an alternate low resistance path for current. Earth is used for the safety of the human body in fault conditions while Grounding (As neutral earth) is used for the protection of equipments.

Earthing:
·         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.
·             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.
·            Under fault conditions the non-current carrying metal parts of an electrical installation such as frames, enclosures, supports, fencing etc. may attain high potential with respect to ground so that any person or stray animal touching these or approaching these will be subjected to potential difference which may result in the flow of a current through the body of the person or the animal of such a value as may prove fatal.
·            To avoid this non-current carrying metal parts of the electrical system are connected to the general mass of earth by means of an earthing system comprising of earth conductors to conduct the fault currents safely to the ground.
·             Earthing has been accomplished through bonding of a metallic system to earth. It is normally achieved by inserting ground rods or other electrodes deep inside earth.
·          Earthing is to ensure safety or Protection of electrical equipment and Human by discharging the electrical energy to the earth.

Grounding:

·         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.
·         Grounding is done for 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.
·         Grounding refers the current carrying part of the system such as neutral (of the transformer or generator).
·              Because of lightening, line surges or unintentional contact with other high voltage lines, dangerously high voltages can develop in the electrical distribution system wires. Grounding provides a safe, alternate path around the electrical system of your house thus minimizing damage from such occurrences.
·           Generally Black wire is used for this as a nomenclature.

All electrical/electronic circuits (AC & DC) need a reference potential (zero volts) which is called ground in order to make possible the current flow from generator to load. Ground is May or May not be earthed. In Electrical Power distribution it is either earthed at distribution Point or at Consumer end but it is not earthed in Automobile( for instance all vehicles’ electrical circuits have ground connected to the chassis and metallic body that are insulated from earth through tires). There may exist a neutral to ground voltage due to voltage drop in the wiring, thus neutral does not necessarily have to be at ground potential.

In a properly balanced system, the phase currents balance each other, so that the total neutral current is also zero. For individual systems, this is not completely possible, but we strive to come close in aggregate. This balancing allows maximum efficiency of the distribution transformer’s secondary winding


The small difference between earthing and grounding concept is:-


§  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. Even though there is a micro difference between grounding & earthing.


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