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What Is an AFCI Breaker and How Does It Work?

Matt Marandola
Written by Matt Marandola
Updated March 24, 2022
Mom and daughter eating a snack
Photo: Flamingo Images / Adobe Stock


  • Arc Fault Circuit Interrupters (AFCIs) detect arc faults throughout the circuit system and determine if they are dangerous enough to flip the breaker.

  • AFCI breakers differ from GFCI breakers by focusing on fire prevention rather than electrocution prevention.

  • Combination AFCI breakers are now the standard; pair them with a GFCI breaker for the best safety practices.

  • Check with your local municipality as they may require AFCI breakers in new constructions or circuit breaker replacements.

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Arc Fault Circuit Interrupters (AFCIs) are circuit breakers required for specific circuits throughout the home. They add an extra layer of protection against arcing conditions that could start fires at the electrical panel. Rather than only detecting overloads and short circuits—which simply shut off the breaker—AFCI breakers are always on the hunt for any type of dangerous arc and working to minimize the impact on the electrical system.

How Does an AFCI Breaker Work?

AFCI breakers are actually a very tiny computer monitoring all types of arc faults. Arc faults refer to a current flowing through an unplanned path. Most times, they are invisible to the human eye. Other times, they are bright and large, like when a power line goes down, and the current jumps to a tree or a stop sign.

The monitoring system in the AFCI breaker constantly looks out for any dangerous arcing that may occur. Arc faults may happen if the wiring insulation throughout the home degrades and suddenly has more paths to leave through. When an AFCI breaker detects any of these phenomena, it trips the circuit breaker to prevent any more current towards that area.

How Does an AFCI Breaker Differ from a GFCI Breaker?

AFCI breakers focus on preventing fires caused by arc faults. This makes them great for fire prevention but doesn’t necessarily focus on protecting against electrocution.

Ground Fault Circuit Interrupters (GFCIs) focus on keeping the electrical current from entering and passing through your body. Luckily, you don’t have to choose between the two, as there are options to have an AFCI breaker paired with a GFCI breaker or install a single unit that contains both.

Types of AFCI Circuit Breakers

There are three main types of AFCI breakers, each providing more protection than the other.

Branch AFCI Breaker

Branch AFCI breakers, the original AFCI breakers, only detect arcing faults in line-to-line, line-to-neutral, and line-to-ground applications. There are also options for Branch AFCI breakers to handle areas that share a neutral wire.

Combination AFCI Breaker 

Combination AFCI breakers are now commonplace for new AFCI breaker installation. These AFCI breakers detect various arc faults throughout the electrical system, including arc faults at extremely low amperage (around five amps). A combination AFCI breaker will also detect arcing in power supply cords in addition to branch circuits. 

Dual AFCI/GFCI Breaker

A dual AFCI/GFCI breaker will do what an AFCI and GFCI breaker does, but with one single component instead—allowing for both fire hazard and electrocution protections.

Are AFCI Breakers Required in Homes?

A circuit breaker board
Photo: makistock / Adobe Stock

The majority of local municipalities will require AFCIs in new residential homes or when replacing a circuit breaker box or panel in the home. There’s no direct law or code in which all 50 states need to follow specific rules, but most states and cities have introduced some form of legislation or code in which AFCIs are now the standard. Even if your area doesn’t require them, it’s still not a bad idea to hire a local electrician to come out and install AFCI breakers to increase the safety of your home.

What Happens if an AFCI Breaker Trips?

An AFCI breaker may trip from something mundane such as an incompatible treadmill or something as serious as faulty or damaged wiring. You should troubleshoot and see if anything plugged into the area is causing the breaker to trip or if it’s something related to the electrical throughout the home. 

  1. Unplug and turn off everything connected to the circuit breaker.

  2. Plug-in or turn on devices one at a time to determine if the problem stems from an appliance, light switch, or the outlet itself.

  3. Test a portable device on more than one outlet to determine outliers.

  4. Check your device’s cords and plugs to ensure there’s no damage or points of failure causing the circuit to trip.

  5. Consider putting less strain on the circuits in case it’s related to electrical overload rather than arc faults.

If your efforts come up empty, and you’re ensure how to tackle the problem, hire an electrician near you to inspect and find ways to get things flowing again.

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