What is Electrical shock? How much our body withstand with electricity? How to protect ourself from earth leakage current?

Electric shock and its prevention

We are very often or rarely sense electric shock. Then a question arises technically , What is Electrical shock? How much our body withstand with electricity?
In Practical, when we are in contact with a live electric wire or touching an electrical equipment with leakage current, a current flow in our body, then we sense the shock.

What is the safe limit of this current?
there are 5 conditions, if the current flow persist in our body and the current limits is 
1) if the current is < 2 mA(Milli Ampere), it is insensible, safe
2) if the current is 2 mA to 10 mA, it is sensible, Let go current and Harmless
3) if the current is10mA to 25 mA, Muscular Contraction occur.(Sensing the shock)
4)  if the current is 25 mA to 50 mA, Ventricular Fibrillation occur, Immediate attention is required, within 20 minutes, we have to give defibrillator to active our heart functioning.
5) > 50 mA - fatal.

How to protect ourself from earth leakage current?
1. Earthing is necessary and must for the electrical appliances used in our home.
2. Now a days ELCB ( Earth Leakage Circuit Breaker) is available in the market, which can be installed  in our house wiring along with other Switchgear. It breaks the current if the earth current is >30 mA range.ELCB will be tripped off automatically, whenever the current crosses the safe limit.

ELCB (Illustration purpose only)