Gentlemen and women:
I am not sure if you all remember, but I had the circuit breaker panel with
the bad aluminum feeder cable that was shooting sparks.
We finally put the new panel in yesterday -- by *we* I mean *I* stood around
while my electrician buddy did the work. We used 6 AFCI's in the panel for
the bedroom and kitchen circuits. When it came time to power the panel back
up, AFCI breaker number 6 refused to latch.
Here is the big question: How do you locate the arc fault that's tripping
the breaker? In this old house the wire is buried deep in plaster walls and
routed from the basement up to the attic and back down again, FWIW, it's not
K&T, just old cloth-covered wiring from the 40's. My buddy had a word for
it I had never heard before -- ragwire.
On Monday, February 22, 2016 at 1:15:58 PM UTC-5, Texas Kingsnake wrote:
You could disconnect it in segments, one at a time, where you have
access, then see if it holds. First I'd pull out all the switches
and receptacles and see what's doing there. Any hard wired loads, eg
attic fan on it? I'd disconnect them. There probably is some
exotic tester that can do TDR or similar to find the fault, but
I don't think it's standard electrician issued stuff.
My electrician buddy didn't have a tester that could detect arc faults.
We've left it so that I have a week to figure out where the problem is and
that means, as you have noted, pulling everything I can from the circuit
until it stops tripping. It's a real nuisance because living room and
bedroom outlets with a lot of important devices are affected.
We reconnected the old plain breaker that wasn't affected by the arc fault
for now and I will disconnect everything I can (and temporarily move things
like the router to other circuits. Then we will reconnect the AFCI and see
if that cleared it. Then I will add back things to the re-enabled AFCI
circuit until the arc fault appears.
My buddy says that in his experience it turns out to be either a power strip
with a partially inserted plug or a back-stabbed outlet that's failing.
Disconnecting all the loads should tell us whether or not it's bad wiring in
the walls or outlets. What fun. I suspected there was going to an issue
replacing the panel. Just didn't expect this!
My electrician friend said that if it's a defect in the in-wall wiring that
it would probably be best to kill that circuit and run a new one with new
wiring and outlets. I tend to agree since this old circuit is cloth-covered
"ragwire" that has no ground. Perhaps it's time to decommission it.
Thanks for your help.
On Monday, February 22, 2016 at 9:50:10 PM UTC-5, Texas Kingsnake wrote:
If it turns out to be one of the things you listed, I don't see it
as much of a problem. It's just unplugging loads, then pulling
receptacles and/or switches out. If the fault is somewhere other
than an accessible, known outlet, junction box, etc, then it's a
That's probably true, but then we can't see what shape the wiring is
really in either.
It seems to be a different story. There is a LOT of stuff blocking places I
need to get to. A huge antique sideboard that takes 4 men to lift is
blocking one outlet and the other is behind an equally bulky dresser.
The old wiring is ungrounded and well over 50 years old. It is run from the
basement into an uninsulated wall cavity, then up to the attic (loaded with
boxes of the cardboard type) and then down through the wall to the boxes.
Both outlets on the problem circuit are on the outside wall where they are
exposed to temperature variants and condensation. Moving what's in front of
them won't be easy for me. I don't think I could do it even with my friend
helping. That's why this is such a bitch.
As I said before, running new, 20A grounded circuits is actually easier
because there are areas where I can use my HF oscillating tool to excavate
some plaster for a new outlet and drill through the floor a lot faster than
moving heavy stuff around in an attempt to preserve an old, 15A ungrounded
cable run. Old plumbing and wiring do NOT like to be bothered much.
I've also read that the arcing can be caused by bad wire nuts and they are
in metal boxes which would limit ignition possibilities. So I am going to
just plod along, map out the circuit as best I can. If removing all loads
doesn't clear the problem, I will kill the problem circuit and run two new
ones. I didn't know until this happened that the bedroom and living room
outlets (actually just half of them) share a breaker. I would rather have
both served by separate grounded outlets and breakers.
If it's easy to run new circuits, I say go for it. I tried to trace a fault
in the outside porch lighting with a fox and hound and even a powered line
tracer. Spent hours pulling boxes, taking meter readings and generally
driving myself crazy. Turns out it was a cable staple that had sawed
through the insulation over the decades just because of general vibrations,
at least AFAICT. Although I couldn't replace all the old wiring with new
runs, I moved a lot of higher amperage loads to new wiring.
When I was trying to find my arc fault I got an AFCI outlet with a pass
through and installed it in the outlet boxes that I had opened. Found a
backstabbed outlet downstream that way. It was arcing, but nothing you
could hear or see.
First thing is to swap wires at the breakers to make sure the new one is not
Then find all the outlets that the breaker goes to. Take them loose one at
a time. Not really the outlets, but the wires going from that outlet to the
next outlet. This will isolate how far the 'good' wireing is.
Make sure you know EVERY place the branch circuit goes!
If you think you can visualize how the wires have been run
(i.e., from panel to this box, then that box, then the next box, etc.)
then you can theoretically reduce the number of "guesses"
by "cutting the unknown portion in half" with each guess.
E.g., if you think the circuit runs:
Box A B C D E F G H I ...
then make your first cut at E (or thereabouts).
This will tell you if the problem lies in the
Box-A-B-C-D portion of the branch circuit or the
[Note that there may be more than one problem!]
If the problem persists in the Box-A-B-C-D portion,
then cut this at B. Now you can narrow it down to
Box-A-B or C-D.
As you will probably be using the (proven non-defective!)
AFCI as a "tester", if the portion of the branch circuit that
you've isolated appears to have the problem (i.e., problem
goes away when you cut the circuit at E -- suggesting problem
lies in E-F-G-H-I), then you will have to reconnect that
portion (verify that the problem REAPPEARS as your tinkering
with it could have "fixed" the problem!) and now find
a spot in the "suspect" E-F-G-H-I segment to cut -- like
This then isolates the problem to H-I or Box-A-B-C-D-E-F-G
(but you already know Box-A-B-C-D-E is good so it's really
The alternative approach is to isolate 'I'. If now tests
OK, then I was the problem. Otherwise, isolate H, then
G, then F, etc.
I tried to get Superman to help me with his X-ray eyes but he's busy
fighting Batman at the moment. <smile> How DO you figure out where all the
branches of a circuit are? I was surprised that one breaker controlled both
living room and bedroom outlets. It seems that each room's outlets are
served by different breakers so that the LR has two different breakers for
outlets on different walls, etc.
Sounds like Newton's method of approximation.
Sweet Jesus. You are making a very strong case for just running another
circuit. The problem is that two overhead lights also run off the bad
circuit and that makes things more complicated than installing two more
grounded outlets (these are ungrounded and probably SHOULD be replaced).
No truer words were ever spoken.
You have just confirmed that running this down is going to be as difficult
as I thought when the problem first appeared.
I suppose I could take everything off the circuit except the overheads, run
two new grounded outlets and hope that fixes things. With the new LED
lights, they probably don't draw enough current to make an arc fault very
dangerous. As I understand it is the big loads that cause the problems with
arcs, but I could be mistaken and often am.
I've heard this method referred to as "grunt and crank".
Some of it is common sense -- knowing how homes TEND to be wired
(though there are caveats). I.e., its unlikely that rooms at opposite
ends of the house will be on the same circuit -- wire costs money
so why run a long length to tie two areas together that could be
better served with different circuits?
You can buy devices to trace wires. Or, just turn on all the lights in
the house and see which ones go OFF when you trip the breaker. Ditto
for outlets (carrying a test lamp around with you).
In your case, that circuit is dead. So, you'll instead be looking
for outlets and lights that DON'T work.
When your list is complete, look at it. Are all of the outlets
in one room listed on the circuit -- except for one? Hmmm... does
that make sense? Maybe double-check it. It *may*, in fact,
be on a different circuit (e.g., may have been added to handle
a new window mount air conditioner, etc.).
The hardest part (esp for older homes) is tracking down things
that might not be obvious. E.g., older homes tended to have
"clock outlets" -- recessed high in the wall for a clock.
If you fail to count all the loads, you may wonder why you've
disconnected EVERY load (receptacle/light) and STILL have a problem!
Ans: you've missed something! :>
Hint: save this list as it now tells you what that ONE breaker
services. You can repeat the exercise for the other breakers
(since they are working, now, you just turn off one breaker at
a time and see what goes off)
I'll wager LR and BR are adjacent? Maybe share a wall?
It's nice if you can feed a room from two different circuits;
splits the load up. I'll suspect one set of outlets service that
half of the room plus an adjacent bedroom; and the other set
are shared with yet another room.
In reality, there are usually not very many loads on a given circuit.
E.g., here I think one of our lighting circuits may have a dozen
loads/fixtures (lamps) on it.
Just treat them as any other "load".
Note that your problem may also NOT be in a junction box/fixture.
There could be a nail driven through a wire *in* the wall, etc.
But, regardless, you'll be able to trace the fault to some
stretch of wire. You can then isolate and/or repair the length
instead of having to rewire the whole branch circuit.
No, it really isn't. You don't have to open any holes into walls, etc.
You're just having to visit each of the LIKELY places that a fault
can develop (junction boxes/fixtures) and see which one is the problem.
If you have a dozen such places, then, worst case, you have to visit
all 12 of them!
Gawd! Every message I have read today just adds to the list of monsters
that might be hiding under the walls. I hope when all the possible loads
are removed, the arc fault disappears and I can add things back one at a
time until it pops. Not sure what I will do if the AFCI still trips with no
detectable loads. I suppose that when I get the clamp ammeter out to see if
there is a load I missed.
It;s really not that bad! And, it's not really *hard* work. It's
FRUSTRATING because you can't see what you are doing... can't tell
if this is likely to be the problem, etc.
But, I'll wager you didn't hesitate the first time you tried to
unhook a bra strap "without seeing"! :>
First make sure the AFCI doesn't trip with NO WIRE attached to it!
Funny you should say that. I just pull the shoulder straps down
simultaneously and keep pulling until it's down around the waist. The
change in diameter from shoulders to waist often unhooks the bra all by
itself. Either way, what needs to be accessed is accessible, if you know
what I mean!
Yep, that's on the list. I've decided to wire a SPDT switch between the two
breakers (now that I have so many open slots) and the circuit wire --
temporarily. That way I can power the circuit through either breaker at the
flip of a switch.
The fox and hound tester might be useful elsewhere, but it wasn't very
useful in this situation. If the break is in the walls, a whole new circuit
will be pulled. Great Caesar's ghost this got complicated in a big freaking
Ah, well I seem to recall sort of being "graded" on "technique".
So, the one-hand approach got the best appraisal!
Of course, back then, it was much easier to impress.
OTOH, I drove SWMBO for some labwork the other day and apparently
managed to "impress" the technician:
"Is that young man with you?"
[I've learned that the only safe answer in these situations is
to SAY NOTHING!! :> ]
I'm not sure why you are adding a second breaker and then wanting to switch
between them. Note that switches come in different contact configurations.
Be sure yours is "break before make" else you can end up shorting one
"side" of the switch (i.e., one of the "DT"s) to the other as the
armature travels from one position to the other. The short will persist
for one or two ohnoseconds... long enough for a profound "Ooops!"
Time for a nap. A 6:00AM day, tomorrow (whoever invented AM should be taken
out, beaten until bloody, then shot -- repeatedly!!)
It's all relative - one young lady exclaimed it was like have her "bodice
ripped" just like the potboiler paperbacks! Back when I went through
puberty girls weren't even wearing bras (wimmen's libbers)! Solved the
problem directly. Ah, the golden age of the Free Love seventies when a
woman was just as likely to undress YOU first. I don't recall ever having
to go through all the bases back then. Women on the street (not just on TV)
actually wore microskirts and see-through-blouses. Then came AIDS and
pantyhose and the party was over. But I "digest."
EVERYTHING was easier back then, or so it seems to my aching back.
Last weeks "Life in Pieces" (about the only good new sitcom I've found, 70
year old James Brolin gets his grey hair dyed jet black and restyled 70's
style. His wife is fine with it until they go shopping and the clerk says
something that ends in "your son." Then she says, "dye it back!"
Well, because I have other things to do and not having light or power on
those circuits is problematic. I've shunted all the loads I can without
stringing the house with 50' extension cords -- a technique that has
remarklably low SWMBO approval ratings. I might rethink that as I get down
to real testing. Somehow, with the old breaker connected things seem far
less urgent than with that circuit dead. I was lying in bed (you apparently
don't sleep much, Buckaroo!) thinking -- got a new panel, got 5 working
AFCI's out of 6, got a new main breaker (part of the new panel) and
legitimate room for expansion -- so why beat myself up about one farking
AFCI breaker that might even be bad? We even down-graded a 15A circuit back
to a 15A breaker instead of the 20A that someone had put in. So things are
While it does bother me that there's something sizzling away in the walls or
somewhere it doesn't bother me so much that I was unable to fall asleep.
How DOES the AFCI figure out there's a bad connection out there?
Got a huge, ancient porcelain-based knife switch that HAS to be break before
make. But there's a lot of exposed copper which makes it probably more
dangerous than an enclosed switch. How do you tell if it's make before
break? Why would anyone ever want to make before break unless the circuit
can not tolerate being unloaded?
This situation has a built in nag factor. My buddy said he would come back
when I had traced the arc fault down so I probably have to show a good faith
effort. He was unhappy about leaving the breaker hanging and the cover off
but I told him I was just going to uncover it anyway and leaving it hanging
would make swapping it out faster.
AFTER he installs the box he tells me that new AFCI panels have an extra
neutral rail -- no more farking pigtails. I asked why we didn't use that
and he said so we could reuse the old (actually quite new) breakers. So I
It would have been nice to get one of those smart panels but you would never
recapture that expense upon resale and I am not sure knowing how much juice
every circuit is using would be useful. At least I think that's what a
smart panel does -- now that I think about it, I am not sure.
On Wed, 24 Feb 2016 00:27:37 -0500, "Texas Kingsnake"
Actually it IS the way it is done today, in MANY cases. Lights in one
room and outlets in another on one circuit - opposite on another
circuit - so if you kick a braker on an outlet, the lights don't go
out in the same room.
If You have a big enough panel, and can afford the copper, each room
having a separate lignting and load circuit would be ideal - with
every room having at least 2 breakers, and each breaker searving only
one location(room). That is, however, not practical..
I am not sure that was done and you have got me thinking - one of the AFCI's
was different than the others - had a little green piece of plastic. I
wonder if a defective AFCI didn't get mixed into the bunch? I will have
him test it next time. The AFCI that popped has been pulled (still hanging
in the box because the pigtail neutral is buried on the first of the tiered
neutral bar connections) and replaced with the old breaker that doesn't
It's a real nuisance to go back and forth between the two - might have to
set up some jumpers so that I can easily change from AFCI to normal breaker
easily. Not sure how I would do that - a pigtail coming off the two
breakers that I can wire nut to the circuit hot wire?
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.