They look alike and both have test buttons, but they guard against different things.
GFCI: protection from shock
A ground-fault circuit interrupter compares the current going out with the current coming back. If a little goes missing, possibly through a person, it shuts off in a fraction of a second. GFCI protection belongs in bathrooms, kitchens, garages, basements, laundry areas and outdoors. See GFCI outlet installation.
AFCI: protection from fire
An arc-fault circuit interrupter recognizes the electrical signature of sparking at a loose connection or a damaged cord. Current code calls for AFCI protection on most living-area circuits. It is normally provided by a breaker. See circuit breaker replacement.
Where they matter in a renovation
A kitchen upgrade, bathroom remodel or finished basement will need both under current code. Dual-function breakers provide the two protections in one device.
Older homes
You are not generally required to retrofit an existing house, but adding GFCI protection near water is one of the cheapest safety upgrades available. For ungrounded two-prong outlets, a GFCI is an accepted way to fit three-prong receptacles. Our outlet installation page covers that.
GFCI Outlet Installation near you
We offer GFCI outlet installation in every town we serve, including Toms River, Woodbridge, Newark, Hoboken, Jersey City and Clifton. See all locations.
Quick answers
Why does my GFCI trip when it rains?
Water is reaching an outdoor box or fixture on that circuit. It needs sealing or replacing.
Should I test them?
Yes, monthly, using the test button.