"Tomsic" wrote in message ...

stuff snipped

Frankly, I expected more nuisance trips based upon what I had been hearing
and reading when the installation was new since, at that time, I was
working
with one of the NEC code panels and there was a lot of discussion about
it.

I agree that the "scuttlebutt" was not favorable regarding nuisance trips.
I was thinking about installing them, too, a while back but after all the
bad luck I had with the first CFL's to hit the market, I decided to wait out
being a pioneer for arc fault technology.

As I understand it, AFCIs react to an electrical arc by sensing the radio
frequencies that the arc generates.

That's fascinating. I just learned that the local water authority monitors
the rebar in their 60"+ concrete water mains acoustically. When one of the
reinforcing bars snaps, it sends out a unique sound that is monitored by a
series of microphones throughout the system and they then replace the pipe
section.

The only problem is that the most recent break occurred where there was no
rebar in one of the large joints. Who would have thunk of monitoring the RF
emissions of an arc or the sound of snapping rebar? As for the AFCI, it
makes sense because the wire leading to the arc must act as a fairly
efficient antenna. I always wondered how an AFCI could differentiate
between normal current draw and the creation of a dangerous arc. Does that
mean you can't use an arc welder on an AFCI protected circuit?

But opening/closing a switch can
generate such an arc (usually very small) and the same thing can happen
when
an incandescent lamp filament fails or electric motors with brushes or
inertia switches power up.

I can live with a breaker popping when a light bulb pops. I've had normal
breakers do that. I assume that like GFCIs (Clare used the term CFCI - is
there a difference?) as they get more feedback from users, they tweak the
design to handle those false triggers better. My first GFCI used to trip
like crazy for no reason. The most recently bought ones hardly ever trip.
I got so suspicious I even bought a GFCI plug-in tester to make sure they
were working. (They were.)

Somewhere out there there's information about nuisance trips and whether
they were over-hyped to begin with or whether the earlier units just
couldn't detect them as well as the newer units do. Our resident sparkies
should know.

As for AFCI's, my understanding (from way back when) is that they were
recommended for bedrooms and bathrooms where a high current device like a
space heater or a hair dryer could create an arc big enough to start a fire
very quickly. I can attest that a space heater plugged in only partially
can create enough heat to melt plastic. DAMHIKT. (-:

I once took apart a six-outlet extender that was getting warm to discover
the copper cross bars were press-fit and had become loose and were starting
to blacken at the place they were joined. I also noticed that these old
press-fit six way outlet extenders had two copper bladed plugs and were
electrically cross-connected. The one I bought to replace the burned-up one
had only one live plug. The other was plastic and just acted as a
stabilizer. I suppose that's to prevent someone from plugging the extender
into an extension cord and not an outlet. That would make the second plug
electrically live and exposed.

There's really no need I can see to cross-connect the two plugs to the six
outlets. It could be set up so that each plug feeds only three of the six
outlets and then you could plug it into an extension cord without creating
an electrocution hazard. Maybe it was an economy thing. After all, not
putting a second copper plugs has to be cheaper if you're making 10,000 of
these things. The best design would be to use two isolated plugs because
that way something like a remotely switched lamp outlet would still work as
it should.

--
Bobby G.