Let’s answer that question in reverse order. You have them because they might save your life.
Faulty electrical appliances can conduct electricity, and if you touch that appliance you’re suddenly part of the circuit. The current flashes through your body to the ground and, well… that’s that. Naturally the danger is compounded when you add water.
But if the circuit is protect by a GFI, so are you.
Ground fault interrupters (GFI) are special breakers that shut off power to a circuit or outlet as soon as they detect a very small leakage of electrical current.
In less time than it takes you to blink — and before you have a chance to feel more than a minor shock, the power’s gone, and you’re still standing.
The Code requires GFI outlets in rooms like the bathroom, but for peace of mind, you may want to install them in places where kids play, too. You can get GFI units which plug into existing receptacles, you can install individual GFI receptacles, or you can install a GFI breaker switch in your service panel, which protects all the outlets on that circuit.
This last option is rather expensive and inconvenient, and it’s usually not necessary. Individual receptacles are economical and easy to install. (Detailed instructions come with the GFI, but if you have any doubts about the wiring, please call an electrician.)
Once it’s installed, use it like any other outlet. If the circuit breaker does trip, you simply press the reset button to restore power to the outlet. But if a particular appliance keeps tripping the switch, have the appliance checked out or replace it.
Test the breaker regularly. Plug in an appliance and press the “test” button. If the power stops, everything’s working fine.