According to a 2006 report from the United States Fire Administration, approximately 67,800 fires occur annually due to problems in a home's electrical system, resulting in approximately 485 deaths, more than 2,300 injuries, and more than $868 million in residential property loss.
Conventional circuit breakers only respond to overloads and short circuits; so they do not protect against arcing conditions. The newer Arc Fault Circuit Interrupter (AFCI) is a type of circuit breaker (or electrical outlet) that breaks the circuit when it detects a dangerous electrical arc in order to prevent electrical fires. An AFCI can determine the difference between a harmless arc that occurs incidental to normal operation of switches & motors, and an undesirable arc that can occur. An example of a arc that may start a fire is when the electrical wire supplying a lamp breaks and it arcs between the broken wires or something else.
AFCI breakers have been become common in bedrooms in new homes built since about 2010. The reduction in fires has improved the usage to spread to more outlets all over the home. Once an unwanted arcing condition is detected, the AFCI opens its internal contacts, thus de-energizing the circuit and reducing the potential for a fire to occur.