-THE AFCI
The “AFCI” is an arc fault circuit interrupter. AFCIs are newly-developed electrical devices designed to protect against fires caused by arcing faults in the home electrical wiring.
-THE FIRE PROBLEM
Annually, over 40,000 fires are attributed to home electrical wiring. These fires result in over 350 deaths and over 1,400 injuries each year. Arcing faults are one of the major causes of these fires. When unwanted arcing occurs, it generates high temperatures that can ignite nearby combustibles such as wood, paper, and carpets. Arc faults may occur for many reasons such as worn electrical insulation or damaged wire, misapplied or damaged appliance cords and equipment, loose electrical connections, receptacle leakage, neutral leads pinched to grounded metal box, wet connections or conduit, shorted wires, wires or cords in contact with vibrating metal, overheated or stressed electrical cords and wires, or driving a nail into a wall and having it inadvertently hit a wire. Arcing faults often occur in damaged or deteriorated wires and cords. Some causes of damaged and deteriorated wiring include puncturing of wire insulation from picture hanging or cable staples, poorly installed outlets or switches, cords caught in doors or under furniture, furniture pushed against plugs in an outlet, natural aging, and cord exposure to heat vents and sunlight. The possibility of arcing grows as a home ages since age and time will contribute to the possibility of these conditions occurring.
Conventional circuit breakers only respond to overloads and short circuits; so they do not protect against arcing conditions that produce erratic current flow. An AFCI is selective so that normal arcs do not cause it to trip.
2. Series arcing (a loose, broken, or otherwise high resistance segment in a single line)
3. Ground arcing (from line, or neutral, to ground)
4. Overload protection (for resistance loads such as heaters. inductive loads such as motors may require additional overload protection)
5. Short circuit protection
The 1999 edition of the National Electrical Code, the model code for electrical wiring
adopted by many local jurisdictions, requires AFCIs for receptacle outlets in bedrooms,
effective January 1, 2002. Although the requirement is limited to only certain circuits in
new residential construction, AFCIs should be considered for added protection in other
circuits and for existing homes as well. Older homes with aging and deteriorating wiring systems can especially benefit from the added protection of AFCIs. AFCIs should also be considered whenever adding or upgrading a panel box while using existing branch circuit conductors.
-INSTALLING AFCIs
AFCI circuit breakers should be installed by a qualified electrician. The installer should
follow the instructions accompanying the device and the panel box. In homes equipped with conventional circuit breakers rather than fuses, an AFCI circuit breaker may be installed in the panel box in place of the conventional circuit breaker to add arc protection to a branch circuit. Homes with fuses are limited to receptacle or portable-type AFCIs, which are expected to be available in the near future, or AFCI circuit breakers can be added in separate panel boxes next to the fuse panel box.
