An arc fault circuit interrupter, or AFCI, is a breaker or outlet that watches for arcing, a dangerous spark in damaged or loose wiring that can start a fire. A standard breaker may not notice it. AFCIs protect against fire. GFCIs protect people against shock. Many homes built before AFCIs were required have none.
What an arc fault is
An arc is electricity jumping across a gap. In home wiring, that gap can come from a nail through a wire, a cord pinched under furniture, a cracked insulation jacket, or a loose connection at an outlet or switch.
An arc can be very hot and can throw off bits of molten metal. If it happens inside a wall or near carpet, paper or insulation, it can start a fire. According to research published by the CPSC, arcing faults are one of the major causes of electrical wiring fires.
What an AFCI does
A standard breaker trips on overloads and short circuits. It is not designed to notice smaller arcs that can still start a fire. An AFCI uses electronics to watch the pattern of current on a circuit. When it sees the signature of a dangerous arc, it shuts the circuit off.
AFCI protection usually comes as a special breaker in the panel. It can also come as an AFCI outlet at the first outlet on a circuit. Some breakers combine AFCI and GFCI protection in one device.
AFCI vs GFCI
The two names sound alike, but they protect against different things.
An AFCI protects against fire from arcing in wiring and cords
A GFCI protects people from shock when current leaks to ground, such as through water
GFCIs are usually found in kitchens, bathrooms, garages and outdoors
AFCIs are usually found on circuits for living areas and bedrooms
Some devices provide both kinds of protection at once
Does my home have AFCIs?
The National Electrical Code first required AFCIs for bedroom circuits starting in 2002, and later editions added more rooms. Each city or county adopts a code edition on its own schedule. Homes in Sun City and most of the older West Valley were built long before that, so most of their original circuits have no AFCI protection.
You can check by opening only the outer door of your panel. AFCI breakers usually have a test button and are often labeled AFCI or Arc Fault. Do not remove the inner cover.
Why an AFCI trips
When an AFCI trips, it is doing its job, or it is reacting to something that looks like an arc. Common reasons include these.
A damaged cord or plug on a lamp or appliance
A loose connection in an outlet, switch or fixture on that circuit
A nail or screw that has nicked a wire in the wall
Some older motors, vacuums or tools that spark inside as they run
A shared neutral wire in older wiring, which can confuse the breaker
A breaker that has failed, which is less common
What you can safely do
Unplug everything on the circuit. Reset the breaker by pushing it fully off, then on. If it holds, plug things back in one at a time. If one item trips it each time, that item is the likely cause. Stop using it.
If the breaker trips with nothing plugged in, the cause is in the wiring. Leave it off and call an electrician. Do not replace an AFCI with a standard breaker to stop the tripping. That removes the protection without fixing the cause.
Testing your AFCIs
AFCIs have a test button. Follow the maker’s instructions printed on the device. In general, pressing the button should trip the breaker. If it does not, the device should be checked.
Living with AFCIs
Once AFCIs are in place, most homeowners never notice them. If one trips now and then, that is a sign it is watching the circuit. A pattern of tripping on the same circuit is a sign that something on it needs attention.
Keep cords in good shape, avoid running them under rugs or pinching them behind furniture, and replace lamps and appliances with cracked or frayed cords. These habits help prevent the arcs that AFCIs are built to catch.
Combination AFCIs
Newer AFCI breakers are often called combination type. They are designed to sense more than one kind of arc, including arcs between wires and arcs along a single damaged wire. If your home has older AFCIs, our electricians can tell you which type you have and whether an update makes sense.
Adding AFCI protection to an older home
Adding AFCIs to an older home is often possible during a panel replacement or upgrade, or one circuit at a time. Older wiring sometimes needs repairs before an AFCI will hold, and our electricians can find and fix those faults.
Call us at (602) 999-2770 and a real person answers. You will hear the price before anyone drives out, and our work carries a two-year warranty on labor and material.
If a breaker trips and you smell burning or see scorch marks at an outlet or switch, leave it off and call an electrician. If you see smoke or fire, get out and call 911.
Common questions
What is the difference between an AFCI and a GFCI?
An AFCI protects against fire from arcing in wiring. A GFCI protects people against shock. They do different jobs, and some devices do both.
Why does my arc fault breaker keep tripping?
Usually a damaged cord, a loose connection, or a nicked wire. If it trips with nothing plugged in, the problem is in the wiring and needs an electrician.
Do I have to add AFCIs to my older home?
Existing homes are generally not required to add them unless work is being done that triggers current code. Many homeowners add them for the added fire protection.
