Electrical Earthing

Why earthing is provided? Ans-
Earthing is provided-

To ensure that no current carrying conductor Rises to a potential with respect to general mass of Earth then and its design insulation,
To avoid electric shock to the human beingsand

To to avoid risk of Fire due to Earth leakage current through unwantedpath.


Question .......

writedown factors influencing earth resistance 
Ans-.......
the resistance of earth system depends upon the following factors:

1. Conduction of soil 2.Temperature of soil
Moisture content ofsoil.

Sizeandspacingofearthresistance

Death at which the electrode isembedded.

Material ofconductor.

qualityofcoaldustandcharcoalintheearthelectrode.




Question........

Discuss methods of reducing earth resistance of the system---

Ans-

The earth resistance can be considerable considerable reduced by

Diggingaroundtheearthelectrodetoadepthofminimum1.5orto2metres.

CleaningthesurfaceoftheearthplateforpipeofallRustandthenfeelingwithcharcoal soaked in saltsolution.
insummersessionthepouringoffreshsaltwaterthroughpipeoverallthecoalbedwill ireduce the earthresistance.
Increasing of plate area ,increasing of pit death and increasing of number of electrodes in parallel.


Question -What is value of Earth continuity resistance? Ans-Follow the answer sheet......

*Question* -

What do you mean by earth electrode earthing lead ?

*Ans* -

Anywire,pipe,rod,ormetalplateembeddedinearthforthepurposeofmakinganeffective connectionwiththegeneralmassofEarthisknownasEarthelectrode.
So,Anearthelectrodeisaconductingelementburieddirectlyintheground,facilitatingtheflow offaultcurrentstowardstheground.

Earthing lead-The wire which connects overhead earth wire or any other apparatus to be earthed to the earth electrode is known as earthing lead.
In other way, we define it as...

Earthing lead is the final part of the earthing system which is connected to the earth electrode (which is underground) through earth connecting point. There should be minimum joints in earthing lead as well as lower in size and straight in the direction.


*Question* -Discuss various methods of earthing with net sketch.


Ans-thevariousmethodsofearthingare: Strip or wireearthing
Rod earthing Pipe earthing Plate earthing.