An arc-fault circuit interrupter (AFCI) detects arcing in the electrical system and turns off the power. Electrical arcing happens when an electric current flows through the air between two conductors (i.e. between two wires). Arcing may occur from gaps or breaks in the wires insulation, overloaded plug outlets, or frayed and exposed wires. Arcing can lead to an electrical fire. An arc-fault circuit interrupter senses any arcing and turns off the power to that circuit to prevent a possible fire.
AFCI vs GFCI
An arc-fault circuit interrupter is very different than Ground fault circuit interrupter that turns off the power if it detects a fault in the ground, which is usually the result of coming into contact with water.
In basic terms
Ground fault circuit interrupter helps prevent people from getting electrocuted
Arc fault circuit interrupter helps prevent electrical fires.
Where you find AFCI
AFCI is most often found as AFCI breakers in the electrical panel box. AFCI outlets do exist but are rare.
Starting in 1999, the National Electric code began to require AFCI protection to outlets in bedrooms. Over the years, the requirement has added more and more rooms, until eventually, they are now required in every room that is not already covered by ground fault protection.
However, local jurisdictions in southern California has been slow to adopt AFCI requirements, AFCI is now required on all new construction outlets, be it an entire new house, a new room addition, or a new outlet in an existing room.
AFCI and Older Homes
The questions becomes, what about older homes built before 1999? I often see home inspection reports where they note the lack of AFCI and recommend an upgrade. However, this is a disservice to the buyer and seller.
The county of Los Angeles is clear that older homes do NOT have to be upgraded to AFCI protection unless the service conductors (i.e. the service wires) are moved more than 6 feet from where they were.
Converting a home that was built before AFCI requirements is not simple, and may involve rewiring the circuits. I believe the main reason there are no official requirements, mandates or codes to upgrade older homes to AFCI is it is simply cost-prohibitive. For these reasons, we do not specifically comment on AFCI on older homes.
That said, if money is not an object, or you plan on extensive remodeling, then absolutely you should upgrade the home’s electrical system to have AFCI protection..