Here are a few items of information that I hope will help balance the discussion with regard to the effectiveness of the AFCI. Some of you are already aware of this information, but there may be some who are not.
It has been stated that AFCIs do not protect against series arcing. This is not 100% true. There is protection against arcing faults that begin as series arcs and progress into line-to-ground or line-to-line (parallel) arcing faults.
Quote from General Electric Advertisement-
"GE AFCI breakers deliver 5 kinds of protection
1. Parallel Protection– direct contact of two wires with opposite polarity
(example: damaged extension cords)
2. Ground Protection – arc between a single conductor and ground
(example: improperly installed wall receptacles)
3. Series Protection – arc across the break in a single conductor, that
progresses to a ground or parallel arc (example: cable pierced by a nail
from a wall hanger)
4. Overload Protection
5. Short Circuit Protection"
It has also been stated that AFCIs do not protect against any arcing faults of less than 75 amps. This is not 100% true either. Some of the “carbonized path” arcing situations were tested with simulated load currents.(5 amps, 10 amps, and 150% of load)
The two Tables below are from a UL document titled “Arc Fault Testing and Arc Fault Scenarios - January 28, 2002” http://www.ul.com/regulators/afci/AFCI_scenarios020502.pdf
Table 1 shows some details of the tests conducted. (X indicates which test was conducted)
(Combination AFCI – This is the (common breaker type) AFCI which complies with the requirements for both branch/feeder and outlet circuit AFCIs. It is intended to protect downstream branch circuit wiring, cord sets and power-supply cords.)
Table 2 shows which type of device provides protection under various conditions. Here again, “Series Arcing Protection” is assumed to mean - protection against arcing across a break in a single conductor, which progresses to a ground or parallel arcing scenario.