Arc Fault Circuit Interrupter
Talk with any experienced firefighter and he/she will quickly tell you any number of stories about houses that have burned because of electrical shorts. The report that the fire department files with the National Fire Protection Agency probably lists the fire as electrical in origin, but the actual cause might have been an arc fault or a similar electrical short.
If you are like most people you probably think the regular circuit breakers in your panel protect against short circuits. Well, they do if certain thermal and over current conditions happen. But an arc or a short circuit sometimes resembles an overactive toaster. In other words, there can be trouble and sparking but the regular circuit breaker doesn't sense a problem. The breaker "feels" okay and is happy with the amount of current flowing through it. Not enough current has flowed through to trip it due to heat buildup within the breaker.
Arc fault circuit interrupters are different. They have intelligence. They can sense when an arc or short circuit is about to spark and cause a fire. They quickly shut down. These new breakers are a huge technological breakthrough. They will save thousands of lives of homeowners and lives of firefighters who enter dwellings to try to save people.
Where Do They Go?
Bedroom circuits are probably the first place to consider installing arc fault circuit interrupters (AFCI). The rooms are typically the farthest distance away from the circuit breaker panel and most susceptible to arcs that can't be detected by traditional circuit breakers.
The next places I would consider would be living rooms, family rooms, basement recreation rooms, etc. You want to protect rooms that have appliances, lamps or any other device that might be occasionally or permanently plugged into a wall outlet.
Eventually the cost of the AFCI is going to drop because of improvements in manufacturing technology. When this happens, it will be affordable to install them on every circuit that is feeding a living space.
Where Are They?
These breakers are in just about every city or town now. You find them at places that sell electric panels and load centers. Forget about visiting a home center! I doubt they would even know what you are talking about.
You want to visit businesses that sell to electricians. Electricians buy from electrical supply houses. For example, here in Cincinnati, Ohio the first two places I would visit would be Becker's and then Richards Electric Supply. These businesses cater to electricians. They will usually sell to a homeowner like you, but you probably don't even know they exist. Why? These businesses tend to target trades people and often feel no need to advertise to the masses like you and me. I must tell you, when you visit a store like Becker's or Richards, you might never go back to a home center! Wait till you see the REAL variety of electrical components that you can buy!
When you finally find the electrical supply houses you might be disappointed. The panel in your basement or garage might not yet have AFCI's available. Don't fret. The manufacturers who don't yet have them will have them shortly.
There are four major circuit breaker manufacturers who are making them. I have them listed in the Arc Fault Circuit Interrupter Manufacturers column. Some of these breakers DO fit into other panels and load centers. You might luck out and get a breaker that will fit your panel! Install the breakers according to code. If you can't, hire someone who can.