The reason for this leakage is, improper earthing of housewiring in your home. Earthing or grounding should be done strongly.
Normally, earth wire coming from the service line is connected to a metal pole which is dig into the earth. Make sure that this connectivity is fine there. Poor connectivity also leads to this problem. If the metal pole should be deeply inserted into earth.
To rectify poor connection, switch off mains, remove metal pole from earth and make deep hole then insert the same and check again for any leakage. If still problem persists, call an experienced electrician to overcome this problem.
Hope this will help!