Used to protect against ground faults, which occur when a person comes into contact with a live electrical wire. This may be caused by worn insulation on a wire or by operating a faulty appliance or power tool.
The GFCI interrupts power quickly enough to help prevent a lethal dose of electricity.
To turn the GFCI back on after it trips, push the reset button located in the middle of the switch.
They can be installed as a receptacle or at the main power panel.