Arc Fault Circuit Interrupters (AFCIs)

A new electrical safety device is now being required in the State of California, and it is called an Arc Fault Circuit Interrupter (AFCI). Since 2003, it has been required to be installed on all bedroom circuits for new construction. This device has the ability to “sense” and detect overheating and shorting of electrical wiring that could start a fire, but would not trip a standard breaker. What’s interesting is that it has taken almost ten years of research and development for this device to be required in residential construction.

In 1992, the Consumer Products Safety Commission initiated the “Home Electrical System Fires Project”, and contracted with Underwriters Laboratories to provide research and evaluations on electrical fires in homes. The research revealed that arcing and overheating of a home’s electrical wiring are associated with more than 40,000 home fires each year, that claim over 350 lives and injure more than 1,4000 individuals.

Arcing occurs when electrical wiring is nicked or damaged, or when there is a loose or poor connection. Nails from installing pictures, wood trim or cable wires can damage electrical wiring. Damage can also occur at power cords caught in doors or under furniture or rugs, plugs in outlets being pushed against by furniture, or cords that are exposed to extensive sunlight or heater vents. Loose joints and poor connections occur outlets or switches or partial breaks in the wiring. All of these conditions can cause arcing, and create high temperatures that can cause fires.

Arcing is dangerous in that it often goes undetected for extended periods of time. It usually begins where it is not easily seen, such as in an extension cord running under the carpeting, at a worn light switch or wall outlet, or at a wiring connection that is no longer tight. In a split second, arcing can create temperatures as high as 5000 degrees Fahrenheit at low current levels. Unfortunately, regular circuit breakers do not respond to signs of early arcing but are rather designed to trip when there are excessive loads and short circuits. They will not trip off when arcing and overheating of electrical wiring produces small differences in the flow of current.

AFCIs are designed to differentiate between normal and unwanted arcing conditions by continuously monitoring current flow. Normal arcing can occur when a switch is opened or a plug is pulled from a receptacle. This is not the type of arcing that usually causes fires or serious electrical concerns. However, unwanted arcing (high heat producing) takes place when conductors touch and separate, resulting in sparks and overheating. When these conditions happen, they are detected the AFCI, and it immediately trips, shutting off the power, and prevents fires from occurring.

The currently adopted edition of the 1999 National Electrical Code in California, requires all electrical outlets in bedrooms of new construction be protected with AFCIs.

Research has shown a large percentage of electrical fires and injuries occur from arcing wiring in bedrooms. Although the electrical outlets in bedrooms represent only a few of the circuits in the house, future editions of the code will require them in other areas and applications.

The good news for the consumer is, this important safety device is relatively inexpensive to install. It can easily be added to most electrical systems in existing homes to provide additional protection for older, and possibly deteriorated wiring.

There are two basic types of AFCI devices currently being used in residential construction. The first type is a circuit breaker that is installed in a main or sub electrical panel of a home. The second is an outlet that is connected directly onto the wiring of a wall outlet. AFCIs can be installed in any 15 or 20 amp branch circuit in the house. Although the installation of either device is relatively straight forward, it is best to consult with an electrical contractor to ensure the devices are properly connected.

It is important not to confuse the ACFI with ground fault circuit interrupters (GFCIs). GFCIs have been required in residential construction since the mid 1970’s. The most common type of GFCI is a circuit breaker or an outlet with the two little push buttons built into the middle of the device. They are usually installed in bathrooms, garages, and kitchens. GFCIs are designed to provide user protection from electrical shock from ground faults.

Electrical shocks from ground faults occur when an unintentional electrical path is created diverting the current to the ground. If this electrical current is allowed to travel through a person’s body, he or she could be severely shocked or electrocuted. GFCIs are not designed to react to hazardous arcing faults that can cause fires, but AFCIs are. Realizing the potential of combining these safety features, manufacturers are already designing devices that have both forms of protection built into one device.

Anyone thinking of updating or adding onto their electrical system, should seriously consider installing this valuable safety device.