Earthing Current

http://en.wikipedia.org/wiki/Earthing_systems

Right straight into the ground...where else?

Potential of the ground is taken as a reference (and hence it is zero).

In fact it may better be treated as a huge conducting sphere, with reference to which one measures the voltages.

All the generating equipments (unless it is done by some mistake) somehow or other (directly or indirectly) has one of its connections earthed.

The earth fault current passes from the user (Say you) to the huge conducting media (earth) and lands up in the generator thereby completing the circuit.

Earth,Atmosphere etc are assumed as sink

Back to the source neutral, thro the earth.

It becomes dark energy....

Quote" we assume potential of earth is zero?" What does that mean?

We use earth(dirt) as a zero reference point with regards to all other points that are part of the electrical system. Any voltage measurements are made between any two points with one of the points being earth or any other point electrically connected to earth.