Designed to shut down if an arc is detected, aka a short between hot
and neutral caused by wire damage. They will trip if you do something
as simple as plugging a small fluorescent light when it is already
turned on. Their main purpose is to drive up the cost of new
construction; additional safety is just a side benefit.
On 22 Oct 2004 17:16:00 GMT, email@example.com (Greg) wrote:
Depends. What is your chance of being involved in such a fire? I
like the idea, but just because it improves safety does not mean it
should be mandated. Why not just ban outlets in bedrooms? That'd
improve safety too.
according to FEMA,
A bit under 14 fire-related deaths per year
per million people,
(not counting military and terrorist activity)
80% of which occur in residences,
a bit under 14% of which occur in bedrooms...
so: .14 x .80 x 14 / 1000000
Thus, your chances of getting killed by a bedroom
fire in any given year are about 0.0001568%,
Of course, it doesn't say how many of those
are electrical fires, but it DOES say the the
three biggest sources of residential fire deaths
are smoking, arson, and problems with your
heating system problems. If we assume that
elecrical arc-fires are number four, then
they can't be more than 25% of that total,
which means that AFCI protection is designed
to save you from a hazard that has a less than
1 in 2.5 million chance of killing you in any given
year. Of course, if you otherwise plan to live
for an even hundred years, your chances of
eventually getting killed by a fire that AFCI could
have prevented go up to around 1 in 25 thousand....
[original post is likely clipped to save bandwidth]
It also doesn't subtract the added deaths due to sleepy persons stumbling
down stairs to reset a false trip.
"There are three kinds of lies: lies, damned lies and statistics."
- Autobiography of Mark Twain
Personal home page - http://gogood.com
gerry misspelled in my email address to confuse robots
The danger is statistically worse than the chance of a kid being killed in a
handgun accident and we know how bad everyone's panties are in a wad over that.
I don't necessarily agree with enhancing the nanny state I am only expressing
the "justification" that is presented.
BTW I haven't felt the compelling need to run out and buy some to retrofit my
I guess your thinking is we should depend more on "battery operated devices"
in the bedroom...hmmmm....I'm getting a thought here...yes...let me run this
by my girlfriend and I'll get back to the group.
Chris Hill is misinformed!
The "arc fault" function of these breakers do NOT respond to the high
current that results when "...a short between hot
respond to excessive current.
An arc fault interrupter (breaker) is designed to sense the condition that
occurs when a intermittent connection produces an arc and therefore,
possibly heat. For example, a wire loosely connected to a wall switch or
lamp fixture might arc and therefore produce undesirable heat, but would not
cause the current to increase.
Likewise, this fault would not result in a current imbalance between the
supply wire (black) and the return wire (white) and, therefore, would not be
detected by a traditional GFCI.
The National Electrical Code (NEC) recently added a requirement that all
bedroom outlets be protected with an arc fault interrupter device. Note -
generally this only refers to new or rehab. work, not to existing homes.
Also remember that the NEC is a set of recommended rules but your community
code is what applies to your property.
[Not to contradict Joe, just to clarify]
An AFI doesn't detect arcs per-se.
An AFI detects extremely rapid fluctuation in current flow (especially down
near to zero), too rapid to be normal demand variations, almost always
indicative of a poor connection and arcing.
As a FYI, AFIs _do_ contain GFI functionality, but at 15ma imbalance trigger
point rather than the usual 3-5ma of dedicated GFIs.
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
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