You can find more information below. Just click on the link!
http://www.ghba.org/pdf/codes/AFCI-Educational-Brochure.pdf
Arc fault breakers are designed to sense an arc in the circuit that they are protecting. We tend to overload those brown and white extension cords and eventually they cause a fire. As seeing this happen it is very devastating to the families involved. The Arc fault breaker is designed to prevent this from happening.
Ever noticed the sparks from motor brushes in tools such as drills and grinders or even some vacuum cleaners? such devices can not be powered thru such over-current devices with arc fault sensitivity. these placed before most non-gfci protected circuits and correct gfci protection on circuits where they are required gets the consumer in a situation as safe possible barring an appliance fault or cooking/heating load malfunction only left err. for these obvious reasons smoke/CO detector alarms installed in multiple strategic locations of structure to alert and protect the public in rare events and power to these devices not be arc fault protected with battery backup accessory included.
Arc Fault circuit breakers are designed to identify the presence of an arcing situation within the circuit they protect. They do this by analyzing the sine wave. An electrical arc changes the sine waves form. The larger the arc,the larger the disruption in the wave. Smaller arcs will not trip the breaker. Those smaller arcs are a normal occurrence in devices that have motors in them. Once the disturbance in the wave form reaches a certain threshold, the breaker is designed to trip.
The purpose of installing arc fault breakers is to try and eliminate fires caused by dangerous electrical arcs. Many fire in homes are started from electrical arcs. Frayed cords, faulty wire connections, and damage in concealed wiring may cause a fire that could be prevented with the use of an arc fault circuit breaker.