Why Use AFCI
An AFCI outlet may reduce the risk of fire in your home caused by arcing. Arcing faults caused by wiring in older homes or wiring that has not been installed correctly can cause a fire. Many home fires may be attributed to faulty wiring. Severe arcing can ignite surrounding wood structural members or insulation.
What Causes Arcing
Arcing can be caused by older electrical wiring in the home that may have insulation that has deteriorated. An electrical wire that has been pierced by a nail during construction or renovation may also cause arcing. Arcing may also be caused by an appliance or light cord that has been kinked or crushed by a piece of furniture or a door.
How It Works
AFCI circuitry has sensors that detect arcing and automatically turn off the outlet when necessary. With the circuit tripped, the current running through the wires has been shut off and the risk of fire caused by arcing eliminated. The AFCI outlet should not trip during normal arcing conditions, such as a minor spark when an electrical cord is removed from the outlet.
AFCI circuit breakers should be installed by a licensed electrician and take the place of a normal circuit breaker in the main electrical box. This gives the entire circuit AFCI protection. Individual AFCI outlets can be installed in homes that have an older main electrical box that contains fuses instead of circuit breakers. Some localities require AFCI protect on electrical circuits in bedrooms in new construction.
AFCI devices -- whether circuit breakers or individual outlets -- should have a test button, in much the same fashion as a GFCI device. The AFCI device should trip, or shut off, once the button is depressed. The device should be checked by a licensed electrician if the test button does not work.