GFCI stands for Ground Fault Circuit Interrupter.  It can also be referred to as an RCD – Residual Current Device. It is an inexpensive, but potentially life saving device that shuts off an electrical power circuit when it detects that the current is flowing along an unintended path, such as through water or a person, instead of just through an appliance.  From that description you can see that a GCFI is a pretty important mechanism that reduces the chance of you getting an unwanted and shocking surprise!


When you look at a typical 120 volt outlet in the USA, there are two vertical slots and a round hole underneath. The left slot, which is slightly larger, is neutral, the one on the right is live or hot, and the hole is ground.

The circuitry inside the outlet monitors the current flowing in the live wire and in the neutral wire. They should be the same. If there is even a small difference between them, it means that some of the current is leaking and going somewhere it shouldn’t. The GCFI senses this imbalance and immediately trips the circuit.


On a GFCI there is a reset button, which may be red or white with the word RESET written on it and a test button underneath that is usually black or white with the word TEST on it.  When you press the TEST button, the RED or RESET button should pop out and cut off the power.

Once the problem that caused the GFCI to shut off has been fixed, you have to manually reset the device by pressing the RED or RESET button. If the button won’t reset then there is still a problem.


You should put GFCIs anywhere in your home where water or moisture will be present, such as kitchens, bathrooms, laundry rooms, utility rooms, wet sink areas, garages, crawl spaces and all outdoor outlets.  They are inexpensive so don’t stint on them.


Just because you have GFCIs doesn’t mean they work. Test them about once a month and before you use an appliance in them. In some appliances, like hairdryers, you may find a mini GFCI attached to the cord of the appliance. Given that most of us use our hairdryers in the bathroom, it doesn’t hurt to be covered twice.