Arc Fault Circuit Interrupters (AFCI) Reduce Fire Hazards

Daniel Snyder : Facility Manager at Community Association Underwriters, Inc.
Yardley, PA

An Arc Fault Circuit Interrupter, AFCI for short, is an electrical device that shuts off power to a circuit when arcing conditions are first detected. Normal circuit breakers open in the presence of a short and may not trip before a fire has begun due to arcing. Up to 40,000 home fires can be associated with arcing and sparking. More than 350 people die and over 1,400 are injured each year in these fires. Property losses are well over $500 million dollars a year.
In an effort to reduce fires and save lives, the National Electric Code, NEC, has made the requirements for AFCI use more stringent. In the 2002 NEC version, only bedrooms were required to be protected by these devices. The 2008 NEC now requires the technology in additional areas of the home such as dining rooms, living rooms, and other living areas. AFCIs are not limited to just receptacles, any branch circuit in the areas listed in the code are required to have arc fault protection, including lights, fans, and alarm and smoke detector electrical wiring. Most builders and electricians have endorsed their use in saving lives and property, and the Consumer Product Safety Commission, CPSC, has tested the devices and found that they are effective in detecting arcs and preventing fires from starting.
AFCIs should not be confused with Ground Fault Circuit Interrupters, GFCIs; a GFCI is a device that provides protection against electric shock. AFCIs address fire hazards while GFCIs address shock hazards. In the future, combination units will be able to provide protection from both hazards. Although an AFCI can be found as an outlet or portable device, they are commonly installed as a breaker in the main panelboard of a home.
Existing homes with standard circuit breakers may benefit from the added protection against the arcing faults that can occur in aging wiring systems as the possibility of arcing does increase the age of the wiring. Other causes for arcs are worn electrical insulation, damaged wire, neutral leads pinched or in contact with a grounded box, wet connections, loose electrical connections, damaged appliance cords or equipment. Even a misplaced nail that damages a wire can lead to arcing.

If considering installing AFCIs in your panelboard, have a qualified electrician install the devices. Even though they can be purchased at most home centers, the way in which your home is wired can cause nuisance tripping. Shared neutrals are one common cause.
The benefits of installing Arc Fault Circuit Interrupters well outweigh the costs. It may only require a few hundred dollars to replace all the necessary breakers in your home with this level of protection, compared to the number of deaths and injuries that occur each year. Another incentive to replace standard breakers with Arc Fault breakers would be lower insurance premiums. Insurance companies will require that the work is either completed by a licensed electrician in many cases, or may require that the work be inspected by the local building inspector. Even without the added incentive of saving on insurance, the knowledge that your home’s electrical system is up-to-date is worth the cost of installation.

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. The possibility of arcing grows the older the home becomes since age and degradation of materials will contribute to the possibility of these conditions occurring.
Nuisance Tripping of AFCIs
Nuisance tripping refers to a circuit breaker or an AFCI that trips off, turning off electrical power when there was no apparent reason to do so. Some "nuisance tripping" of AFCI’s actually occurs due to wiring practices of some electricians more than for any other reason. Such as the following:
• Reversed hot and neutral wires - reversed polarity - which is an unsafe condition
• Shared neutral wiring on single pole circuit breaker circuits: this is already an existing problem with GFCI’s on multi-wire branch circuits.
• Incorrect or accidental connections between the ground and neutral wire: this is also an unsafe condition which can permit live current to flow on a ground wire that should normally never carry current.
A common source of accidental ground-neutral connections occurs when an electrician over-tightens the clamp connector on BX, armored cable, where it connects to a steel junction box. Over-tightening the connector pinched the edges of the BX cable. If the BX cable edge cuts into the hot wire the breaker would trip immediately when power is restored to the circuit. If the cable edge cuts into the neutral wire, the problem would go unnoticed until a GFCI or an AFCI is installed on the circuit, or until someone touches a supposedly safe armored cable wire exterior and gets a shock.
For more information about AFCIs, contact an electrical supply store, an electrician, or the manufacturer of the circuit breakers already installed in your home. Sometimes these components can be replaced with AFCIs in the existing electrical panel box.
Be sure to have a qualified electrician install AFCIs; do not attempt this work yourself if you are not qualified. The installation involves working within electrical panel boxes that are usually electrically live, even with the main circuit breakers turned off.

Safety Warning:
Do not attempt to work on your electrical wiring, switches, or outlets unless you are properly trained and equipped to do so. Electrical components in a building can easily cause an electrical shock, burn, or even death.