On 07/05/2013 07:37 PM, bud-- wrote:
On 7/4/2013 8:13 PM, gregz wrote:
An arc fault breaker is not also a ground fault is it. Are there some ?
AFCIs include ground fault protection. I believe it is required at 50mA
or less and is provided at 30mA. The cpsc.gov link I posted has
information on ground fault protection and why it is included.
GFCIs will trip with a ground fault of 5mA, so AFCIs don't replace
GFCIs. Another difference is that GFCIs have a couple additional
components that will trip the GFCI whenever there is a downstream N-G
connection, load or no-load. AFCIs will trip with a N-G downstream
connection (as gfretwell wrote) but there has to be a load to produce a
voltage drop on the neutral wire.
I don't think the NEC requires both GFCI and AFCI protection at the same
location. GFCI wire-through receptacles can be used downstream from AFCIs.
OK, I see that the question was already answered... sorry...
I actually had a situation where I was required to use AFCIs and GFCIs
together. In my last house while I was in the process of rewiring the
upstairs, I had half of the floor properly grounded and half still using
the original cloth covered ungrounded NM cable. Unfortunately the PO of
the place had installed grounding type receptacles anyway throughout
even though there was only originally one box with a proper ground.
Strictly reading the code at that point I could not install ungrounded
receps (I did order some but never installed them - my eventual goal was
to rewire the rest of the floor including the original wiring that was
still reasonably acceptable, but we sold the place first) alternately I
could provide GFCI protection. So that is what I did, I installed a
GFCI recep at the first box on the circuit and an AFCI breaker in the
panel (since it was a floor with three bedrooms.)
It seemed like a Mickey Mouse setup, but I never had any trouble with it.
One concern I did have though was what if someone were living in a house
that needed some kind of life support equipment? Could not a nuisance
trim be potentially fatal? I'm guessing people more knowledgeable than
I have already run the numbers on this and have determined that AFCIs
are less of a net risk than not having them.
nate
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