Creepage protection plug is also called "Residual Current Protection Plug". When the electrical appliance leaks electricity, in the electric return circuit there must be some electric current not to flow back to the voltage transformer from the line by the Neutral, but flowed into the earth by "conductive body", such as the ground or the human body and form a tributary beyond main circuit. The electric apparatus in the work has this tributary, but what we said at ordinary times "leak electricity".

When the insulation in electrical appliance is not fine, the electrical appliance will leak electricity. But when this part of electric current flows into the earth through the human body, it will cause people to get an electric shock. Before electric current has not injured the human body yet, creepage protection plug can cut off the power automatically and have protected the personal security.