AFCI ?! It's about time !
I've related this before but it is timely again, concerning
safety in the home.
One afternoon my wife who was sitting on the edge of the
bed at the time, called me over, saying, "Listen to this."
There was a distinct "zzhht", "zzhht" sound coming from
somewhere behind the night stand. The sound got louder,
and became constant, until flames erupted up along the wall
about six inches from the curtains.
I pulled cords out of the outlet by their cords, which
stopped it all, except for some "stinky" smoke.
Upon investigation I found that the UL approved outlet and
UL approved cord plugged into the outlet [not supplying
power to anything at the time, simply plugged in] had
sustained an arc between the blades. An arc that
carbonized the plastic, sustaining the arc more. Not
enough current to take out the 20A breaker, but enough
current to BURN the plastics, ignite the plastics, and set
up a potentially devastating fire.
I was livid that UL approved items that would deteriorate
in this manner. Upon checking with the local Fire
Department, I found that this scenario was almost the
number one cause of fires in homes - damage *and* loss of
life.
If we had not even been in the room, this could have gotten
out of hand very quickly.
So the AFCI function you describe is really worth it.
PS. Since this experience I have embarked on an annual
inspection/maintenance program for all electricals. Just
didn't know how necessary it was before.
- Robert -
On Mon, 29 May 2006 13:21:13 -0500
[email protected] wrote:
> I would also like to mention a new type of device that is
> now required for
> certain installations in the United States. There is a
> device called an
> Arc Fault Circuit Interrupter, AFCI. An AFCI is only
> require in a few
> locations, including circuits for bed rooms. The purpose
> of the AFCI is to
> detect faults in wiring that are resulting in arcing. It
> is intended to
> detect arcing both phase to neutral and phase to ground.
> The AFCI devices
> incorporate a microprocessor that is looking at the
> current on the phase to
> detect sudden changes that could be arcing. However, the
> current measured
> from arcing can look a lot like the current resulting
> from dimmer switches
> and switch-mode power supplies. Most AFCI manufacturers
> have proprietary
> firmware and will not give information on the precise
> algorithm for their
> devices. However, it is clear that switch-mode power
> supplies are very
> likely to trip AFCI devices. Unlike a GFCI, the AFCI
> will trip when
> detecting very short current transients.
>
> Ted Eckert
> American Power Conversion Corporation
>
-
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