In 1999, the National Electric Code (NEC) required the use of Arc Fault Circuit Interrupters (AFCIs) in bedrooms, effective adoption in January 2002. These are most frequently seen as breakers with funny green, blue or yellow buttons on them in your sub panel often located in the garage. Many years ago, a CPSC study identified arc fault detection as a promising new technology. Since then, CPSC electrical engineers have tested the new AFCIs on the market and found these products to be not perfect but very effective. AFCIs use unique current sensing circuitry to discriminate between normal electrical arcs and unwanted arcing conditions then de-energize the circuit like the GFCI breakers do. Their intended function is to prevent fires. In older homes with aging and deteriorated wiring and unprotected circuits, the use of GFCI and AFCI devices can be very beneficial.
Problems in home wiring like arcing and sparking, are associated with more than 40,000 home fires each year! An insurance company study determined that over 33% of fires in nearly 700 cases were from arcing faults. Arc faults most often occur in damaged or deteriorated wiring and cords creating very high temperatures which can ignite nearby combustible stuff. Sometimes the damage comes from home decorators hanging pictures when nails penetrate unseen wiring. Cords through doors and windows are not bright idea either.
Typical household fuses and circuit breakers do not respond to early arcing and sparking conditions in home wiring. By the time a fuse or circuit breaker opens a circuit to defuse these conditions, a fire may already have begun. The AFCI’s circuitry continually monitors current and can discriminate between normal arcs (when a switch is opened or a plug is pulled from a receptacle) and bad arcs. The sensing circuitry de-energizes the circuit super quick thus drastically reducing the potential for fires. An unwanted arc occurs when conductors touch themselves or another grounded metal surface.
If you live in a house built after 2002, look in your breaker panels. You should see breakers that have that old familiar look of a GFCI breaker but the AFCIs are usually different colors and will be labeled “AFCI” and/or “Arc Fault Circuit Interrupter”. They offer the traditional overcurrent protection plus the arc fault protection. They are tested manually with these buttons just like the GFCIs too.
Requiring AFCIs
AFCIs are already recognized for their effectiveness in preventing fires and were originally required for bedroom circuits in residential construction, but should also be considered for protection in older wiring systems. The older homes can especially benefit since wiring and insulation deteriorate with time and exposure. Newer standards since about 2011 require AFCI protection on pretty much every circuit.
While both AFCIs and GFCIs are important safety devices, they have different functions. AFCIs are intended to address fire hazards; GFCIs address shock hazards. Combination devices that include both AFCI and GFCI protection are also available.
