An Arc-Fault Circuit Interrupter, AFCI for short, is an electrical device designed to help prevent house fires. The way it does this is by “tripping” or opening the circuit if it detects an unintentional arc. You may have seen an arc at some point when you turned a light switch on or off. This is caused by the tendency of electricity to discharge high voltage across a small gap. You have likely felt electrical arcing, especially during the wintertime when the air in you home is more dry, after walking across a carpeted floor and touching a door knob, another piece of metal, or another person. The static electricity that you feel is actually the heat being generated when the voltage that has built up in your body (tens of thousands of volts) discharges across the gap as you hand reaches for that doorknob.
As you know, there is electrical wiring running throughout the walls, attic and possibly the crawlspace in your home. If any of this wiring is damaged, or if there is a loose connection somewhere, then it is possible for arcing to occur. Wires can be damaged in several ways including by rodents chewing on them or by a nail driven into a wall to hang a picture. Electrical arcing can also occur if you plug something with a damaged cord into an electrical receptacle. Due to the heat generated by arcing (several thousand degrees for a very short time), it is possible for this arcing to ignite flammable material nearby and cause a housefire. Arcing is an instantaneous event, but when there is a damaged wire in a wall, this event will occur over and over, essentially continuously, and will generate a lot of heat in the wall. This heat can cause wood, insulation or other flammable material nearby to ignite. AFCIs help to protect against house fires by continuously monitoring the electrical current in a circuit and shutting off the circuit when unintended arcing occurs.
Where are Arc-Fault Circuit Interrupters Required for AFCI?
Electrical standards and requirements are changed and updated frequently, so you may want to ask a licensed electrician in your locality for the latest requirements. However, as of the 2017 National Electrical Code (NEC), Arc-Fault Circuit Interrupters are required on all 15-amp and 20-amp, 120-volt branch circuit locations in all dwelling units. In other words, they are required on almost all 120-volt circuits in your home. A 120-volt circuit includes the standards outlets throughout your home that you plug most things into. 240-volt circuits are not included in this requirement. 240-volt circuits are the circuits for heavier electrical loads such as an electric furnace, a clothes dryer, an electric oven, water heater, etc.
How Can You Add Arc-Fault Protection to Your Home?
Contact a licensed electrical contractor and have them evaluate your home, and give you a bid to do this for you. It is normally as simple as replacing several breakers in the breaker panel, so it is not a real expensive thing to achieve, and it will definitely make your home and family safer.
There are actually three ways to achieve arc-fault protection for your home;
- Install Arc-Fault breakers (AFCI breakers) in the breaker panel:
- Replace all of the appropriate electrical receptacles with AFCI receptacles; or
- Replace only the upstream receptacle in each circuit and allow that AFCI-protected receptacles to protect all of the wiring and receptacles that are downstream of the it.
In my opinion, the simplest of these methods is the first method (installing breakers on the necessary circuits).
What is the Difference Between AFCIs and GFCIs
This is a common question. I have also been asked the question, “I have GFCIs in my home already. Do I still need AFCIs?” While AFCIs and GFCIs look similar and both shut off the power to the outlet or to the entire circuit if they detect a fault, they are protecting you from two totally different types of problems or faults. GFCIs protect people from getting electrocuted if a ground fault occurs. AFCIs protect against house fires due to electrical arcing in the wiring.