"bud--" wrote in message
eb.com...
On 7/17/2013 2:02 PM, Robert Green wrote:
wrote in message
b.com...
On 7/16/2013 2:34 PM, Robert Green wrote:

I am not sure I am going to create a
carbon arc - only because I can't seem to find my stash of carbon rods
at
the moment. I might try to arc some pencil leads but that would have
very
low SAF.

If you use carbon rods or some similar arc I suggest you use something
like the 1500W space heater in series. That limits the current. Else
you
can have a current that is the available fault current at the outlet,
which one of the articles said is 60A or higher (if I remember right).

Thanks. That sounds like an excellent idea. I recall reading that as
well.

Obviously this is a shock and fire hazard.

I'm souring on the carbon-arc testing based on what you've pointed out
and
how far away it is from real-world faults that are likely to set off the
AFCI.

But think of the fun....

(-:

From looking around it seems that cost-wise, GFCI breakers with
AFCI
outlets
in the cheapest way to go.

But that does not necessarily protect the house wiring. The NEC allows
an AFCI receptacle to protect a branch circuit if it is the first
device, and the branch circuit is wired through it, and the wiring to
the panel is something like in metal conduit.

I've only got the NEC updates guide so I am not sure what the codes are.
I
assume the reason the feed to the first AFCI receptacle should be in
conduit
is so that if an arc does form before reaching the protection device,
it's
safely enclosed and not like to spark a fire.

Correct. (It is a little broader than just metal conduit, but I am too
lazy to look it up.)

I'm going to have to content myself with making things marginally safer but
not as safe as they could be. I'd like to have GFCI/AFCI protection on
every circuit but for now only the ones that pose the greatest threat will
get upgraded.

The circuits I want to
protect are all new ones I installed to power devices that I didn't want
to
run through old, cloth covered wiring runs rated (when new) at 15A.
They
are circuits for window ACs, toasters, microwaves, space heaters and the
workbench outlets powering the RAS and other power hungry tools.

The current NEC generally requires AFCI protection in a house for new
circuits that don't have to be GFCI protected. (And gfretwell recently
wrote that the 2014 NEC adds laundry and [another one] that will have to
be AFCI protected.

I can't figure out why the AFCI outlets are
cheaper than the breakers, but that seems to be the case. My best
guess
is
the size factor - they have to "shrink" the AFCI components to get
them
to
fit into a breaker slot.

If you need an AFCI breaker for a SquareD panel it comes from SquareD
and they can charge more. Receptacles can be made by anyone (although I
don't know of anyone but Leviton that make them now).

That sort of makes sense. (-: I am reluctant to use AFCI breakers
because
of the pigtail issues (the circuit box is crowded enough) and with
outlet
AFCIs I can quietly remove them (yes, I know they are fixtures and
that's
technically a no-no) and replace them with standard outlets when I move.

They kinda become non-code compliant.

I think my post in a recent thread got into use of AFCI receptacles.

The NEC now wants AFCI protection on most new house circuits and
extensions of existing circuits where the extension is in an area that
requires AFCI protection.

It makes sense. I just wish a complete upgrade wasn't a job of titanic
proportions.


Here's another question. What does "Spec Grade" mean on the Leviton
AFCI?
Is it just marketing hype?

You can also get regular receptacles and switches that are "spec grade".
It is a higher quality and should last longer. Might be particularly
good in a kitchen.

The other grade is "consumer" or "builder" (and there may be an
intermediate grade).


Do you know how the plug-in GFCI testers with the pushbutton work? Are
they
creating a current mismatch between the two conductors?

The connect a resistor from the hot wire to the ground wire. The
resistor is sized for about 5mA. The current on the hot wire is 5mA
higher than on the neutral. They do not work if there is no ground.

I didn't realize they need a ground to operate correctly. I should have
saved the manual.

GFCI receptacles and breakers have the same resistor but connected from
the downstream hot to the upstream neutral (or vice versa). The current
on the hot and neutral are about 5mA different. The ground wire is not
used and the test will work on a receptacle without a ground.

You answered my next question before I asked it!

A "snap" switch likely has an AC-DC rating. The silent switches are an
AC only rating.

Hmm. Do you know why that is? Is it related to arcing or some other
issue?

When switching AC, the zero-crossings help extinguish the arc of the
opening contacts. DC can arc much farther and you want a fast acting
(snap) switch. If a switch has both AC and DC ratings, the DC voltage
rating should be considerably lower than the AC rating.

AC only switches have a motor rating at something like 80% of the normal
rating. Not likely AC-DC switches do.

I see. I had noticed the disparity in switch ratings before but had no idea
until now why they should be rated differently. Thanks for the edumacashun.

--
Bobby G.