GFCI and AFCI protection explained

GFCIs and AFCIs are two kinds of protection built into outlets and breakers. They look ordinary, but each one watches for a specific danger and shuts off power in a fraction of a second.

GFCI: protection from shock

A ground-fault circuit interrupter (GFCI) cuts power when electricity starts leaking out of its normal path, for example through water or a person. That’s why GFCI protection is required in places where electricity and water can meet. Under the National Electrical Code, those typically include bathrooms, kitchen countertops, garages, outdoors, laundry areas, and unfinished basements and crawl spaces.

AFCI: protection from electrical fires

An arc-fault circuit interrupter (AFCI) detects dangerous arcing, the kind of sparking that can happen with damaged cords, loose connections or a nail through a wire, and shuts the circuit off before a fire can start. ESFI notes that the National Electrical Code requires AFCIs in bedrooms and living areas of newly constructed homes.

Code requirements vary by location

Each state and city decides which edition of the electrical code it adopts, so exact requirements differ from place to place. Older homes were built to older codes and may not have GFCI or AFCI protection everywhere a new home would. A licensed electrician can tell you what makes sense to add in your home.

How to test them

• Press the TEST button. Power to the outlet or circuit should shut off. Press RESET to restore it.
• ESFI recommends testing GFCIs and AFCIs monthly.
• If a device doesn’t shut off when tested, or won’t reset, have an electrician replace it.

When they trip

• A trip means the device did its job and saw something it didn’t like. Unplug what was running on that circuit, then reset.
• If it trips again right away, or keeps tripping with nothing unusual plugged in, there may be a wiring problem or a failing appliance. Call a licensed electrician rather than resetting it over and over.
• One GFCI outlet can protect other outlets "downstream" on the same circuit. If an outlet in a bathroom or garage is dead, look for a tripped GFCI nearby.