Earthing

Go with the first sentence.

first sentence is related to below ground level...

second sentence is related to above ground level...

Now tell me where is the conflict...!!!

so what ?

both are added to calculate ground resistance

Quote "As i know earthing aim is to reduce the resistance of earth to provide a path for the fault current"

Please don't say that.

There is confusion when you use the term earth. Are you referring to earth(dirt) or are your referring the the neutral of the system. An earth(dirt) fault has a high resistance and current flow is a low value. A Phase to neutral(sometimes called ground) fault will have a low impedance and the current flow is a high value. Regarding distance, the fault will flow back to the source. Earth(dirt) is not a "sink hole" and does not absorb the fault current.

Earthing , per the OP seems to mean a connection to mother earth(dirt). Earthing a piece of equipment will not provide safety in the event of a fault. The resistance of the earth is too high to allow enough current flow to trip a breaker. Bonding or grounding the equipment is the method used in the US to cause the breaker to trip. An Equipment Grounding Conductor EGC is installed with the power conductor and connected to the equipment. The EGC is bonded to the metal frame at one end and to the Main Switch and grounding electrode at the other end. This provides a path for the fault current to flow.

In a substation

earthing pits are made which have an electrode which is buried deep into the ground . there can be many earth pits .

in a 66kv substation where i worked during its construction there were three separate earth pits for Surge arrestors .

and two separate earth pits for earthing the neutral of the secondary side of the delta star step down transformer

also Galvanised Iron strip was layed across the ares of switchyard .this net was connected to some more earth pits . In the end the switchyard was cover with big balck gravel .