An arc fault circuit Interrupter (AFCI) is different from a Ground Fault Circuit Interrupter (GCFI) in a couple ways.  AFCIs monitor arching in branch wiring in a home while GFCIs monitor the current flow in electrical wiring.  Arching is when the pattern in the electrical current changes which can cause electrical currents to jump from one place to another.  The best example of arcing is the spark you see while plugging in or unplugging something from an outlet. An AFCI detects these arcs and are meant to respond to arcing that is excessive and dangerous at the point of the arc.   A GFCI is intended to detect a ground fault.  A ground fault is when a current leaks from an ungrounded conductor to a grounded object (possibly a person) due to a short circuit.  A GFCI will trip the circuit before a shock happens thus preventing personal injury or death.




AFCIs are intended to prevent fires and property damage.  Electrical currents flow in a consistent wave of peaks and valleys.  If this pattern deviates at all an AFCI monitor will catch it and immediately shut down the current so that a dangerous arc doesn’t occur and cause a fire. Arcs are usually the result of damaged wiring insulation or improper installation of wiring. If a wire is pinched between to timbers as a result of a house settling for example, the current could arc to the wood frame and cause a fire.  Some other causes of arching are:

  • The over-extension of appliance cords
  • Electrical appliances or outlets that come into contact with a liquid
  • Connections that are or become loose in an outlet, light fixture, or switch
  • Damaged electrical cords


Millions of dollars, thousands of homes and hundreds of lives are lost each year as a result of fires caused by the types of arcs that AFCIs prevent.  Traditional breakers do not detect or react to dangerous arcing.  All new construction should have AFCIs installed in the bedrooms according to NEC (National Electrical Code).  It is further recommended that all 120-volt, single phase, 15 and 20-amp branch circuits in a home have AFCIs in them.


When you have AFCIs in a house it is possible for them to trip unnecessarily.  To avoid this nuisance there are a couple things you can do.

  1. Check that all wires are connected properly and tightly
  2. Make sure that no neutral connections on a circuit are shared
  3. Use an AFCI testing device to be sure the AFCI is working properly and to find a source of nuisance tripping if one exists


AFCIs Available


Outlet AFCIs, Branch AFCIs, Combination Outlet/Branch AFCIs, and Cord devices are all widely available at home improvement and electrical supply stores.  Each serves its own purpose and you should discuss your needs with a professional to decide which is best for you.