The year 1980 marked a terrifying statistic. It was the peak of home structure fires according to the National Fire Protection Association. 75,000 homes were destroyed in the United States, the largest number in the world. Not only were the structures damaged but many people were injured or lost their lives because of these fires.
After much research, it was determined that many of these fires occurred in homes with branch circuit wiring. This spurred the invention of the Arc-Fault Circuit Interrupters (AFCIs) and the National Electrical Code requirement. 25 years have passed since their invention with much work still to do.
The AFCI is intended to stop an unintentional arcing condition in a circuit. The temperatures of these arcs can reach as high as 10,000 degrees Fahrenheit. This results in burning particles that can ignite wood or insulation very easily.
The AFCI uses electronic technology that monitors normal versus dangerous arcing conditions. Different electronics in the home create natural arcs. These normal arcs are created by vacuum cleaners or even a light switch. The AFCI is able to determine the difference been natural and normal arcs and dangerous arcs that could cause a fire. These dangerous arcs can be caused by damaged equipment, equipment failure, corrosion, improper maintenance, faulty installation and more.
AFCIs should be installed in all 120-vault, single-phase, 12- and 2-ampere branch circuits supplying outlets or devices installed in dwelling units. They are not required in all US states, but can be installed regardless for safety purposes.
There are different types of AFCIs. The Branch Feeder AFCI is installed at the origin of a branch circuit or feeder like a panelboard. This is for detection of faults that occur line-to-line, line-to-neutral and line-to-ground. In older homes, to accommodate a three-wire circuit arrangement, it is possible to use a two-pole AFCI. A Combination AFCI includes the Branch Feeder AFCI and provides for series arc detection down to 5 amperes. This helps to detect lower-level arcing in branch circuits and power supply cords. AFCIs can be used in conjunction with Ground Fault Circuit Interrupters (GFCI). It is common to use an AFCI circuit breaker with GFCI receptacles. This creates greater protection for the homeowner.
All AFCIs on the market must be evaluated by a nationally recognized testing lab to ensure they meet the national standard – UL 1699. The requirements are set in NEC 210.12.
Although great strides have been made with more stringent regulations and better knowledge for both professionals and homeowners, there is still progress to be made. Homeowners can take extra precautions to keep themselves safe. Check all cords to ensure they are not damaged, double check extension cords to make sure they are being used properly, update the circuit breakers in the home, check appliances and finally hire a professional.