On 7/5/2013 5:56 AM, Robert Green wrote:
wrote in message
news:51d42b22$0$1355$c3e8da3

Looking at the current in the wire, a "spike" is made up of frequencies
that are much higher than 60 Hz. My guess is AFCIs look at the low end
of RF and what is in the audio frequencies. I would also guess AFCIs
pick up the current signal with a current transformer on the hot wire.
(GFCIs use a current transformer around both the hot and neutral.)

It's interesting that in all my research I've yet to come across a circuit
diagram or anything technically detailed about how AFCIs actually work. I'm
going to bite the bullet and order an AFCI outlet to run some tests with.
They ain't cheap!

I dug into my archive of downloads. Of particular interest is
http://www.cpsc.gov/volstd/afci/AFCIFireTechnology.pdf
why have AFCIs
available fault current on a branch circuit
AFCI detection - block diagram
"bad" arcs and normal arcs
30mA ground fault detection
It might answer some of your questions.
Details of detection, as gfretwell wrote, are probably proprietary.

Likely of less interest is:
http://web.archive.org/web/200805160...gregmanche.htm
includes info on 5A trip
Note that "branch/feeder AFCIs" were the original ones that did not
detect series arcs and are no longer available.

Prices likely will decline like GFCI prices did. But AFCIs are more
complicated.


http://www.amazon.com/Leviton-AFTR2-.../dp/B009ZZCKG8

runs $33 from Amazon. If anyone knows of a cheaper vendor, please advise.
Also, how would one go about creating a deliberate arc for testing purposes?
I've got some carbon rods lying around somewhere that I used to create a
carbon-arc light with. I suppose that should work . . .


You can also use mechanical pencil leads wired in series with a load
that runs at higher than 5A. Pencil leads give a pretty smooth arc. Is
it a "bad" arc or a "normal" arc?
Check the cpsc.gov link for some info on good and normal arcs.

I would just assume that if the test button works the AFCI is OK.
There is a page at UL that says about what TimR got from inspectapedia.
I do not find it surprising that testers are not available.