Ground fault circuit interrupters (GFCIs) are an important electrical safety feature. A GFCI outlet contains a sensor that monitors the amount of power going to an electrical appliance. If there is an interruption in current the GFCI cuts the power, potentially saving a life. These monitors are especially critical in bathrooms, kitchens and anywhere else water is present in the environment.
Because GFCIs can fail without notice, it’s important to check them monthly. Pick a day you will remember, such as the first or last day of the month, so you are sure to maintain a regular schedule.
Follow these instructions to safely test your GFCIs.
Shut off power before you test; to confirm the shutoff:
To test the GFCI outlet:
To reset the outlet:
Once you confirm the GFCI is working properly (that the outlet does not work when tested), press the reset button to restore power to the outlet
Retest for all other sockets in your home
Other options for testing:
You can also buy a GFCI outlet tester with a display and test button
GFCI protection can also be installed on circuit breakers to safeguard an entire circuit. They should be tested monthly by pressing the test button on the breaker. If working properly, the interrupter should shut off power to the circuit.
Source: Safe Electricity