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.
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.
First thing is to swap wires at the breakers to make sure the new one is not faulty.
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 E-F-G-H-I portion.
[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 at G.
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 just E-F-G!)
The alternative approach is to isolate 'I'. If now tests OK, then I was the problem. Otherwise, isolate H, then G, then F, etc.
Cut out the feed that runs up the wall behind the plaster and replace it with new cable Bypassing that old chunk of wire eliminates it as a cause. If it still trips, remove EVERY device fastened to that circuit. Pull every switch, receptacle,and fixture. If it still trips rewire more untill you have it fixed. (you DID try disconnecting the circuit from the AFCI in the panel to be sure it's not a defective AFCI - right???)
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.
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 trip.
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?
I tried to get Superman to help me with his X-ray eyes but he's busy fighting Batman at the moment. 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".
I suggested swapping breakers but by that time my buddy wanted to get home and so we'll do it next time. Right now it's back on the old, plain breaker that doesn't trip while I shunt the current loads on that circuit over to other, nearby outlets. I suppose if I move the loads to one of the new AFCI enabled circuits and that one trips, I've found the culprit.
I guess this is a good thing (revealing an arc fault that was unknown until now) but it sure seems like it is going to become a major pain in the ass.
In the meantime, since we had to rearrange a number of breakers to accommodate the old, short ragwire connections, I need to check each circuit one at a time to correctly ID it in the panel. We did the best we could to preserve the old numbering but it is time to double check things.
I guess now I will be marking outlets with a circuit number and a letter to indicate which one preceeds another. That isn't going to be easy nor accomplished without disturbing an awful lot of existing wiring -- and the plaster covering it, too. Sheesh. Goes to show that no good deed goes unpunished. Never expected to hit this sort of problem.
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!
Get yerself a "fox and hound" tester. Turn off the breaker and plug the fox into one of the outlets and set the hound loose - tracing the wires from that outlet both ways - back to the panel and on to the end if you didn't manage to find the last outlet in the string. If you have metal lathe in your plaster it will make things more difficult, but not necessarily impossible.
Have you checked to see if it could be a defective table lamp, light fixture or appliance. Some items that you may think that would never cause a problem are doorbell circuits or a clock radio. An engineer friend who worked for the power company communications division would often track down RFI caused by doorbell transformers which were sizzling/arcing but not drawing enough current to burn up or trip a standard breaker. You may have a light left on in an attic or basement/crawlspace that has a burned center contact or rivet at the bottom of the socket shell that is arcing. I've seen all sorts of weird crap cause problems in electrical and electronic circuits and only discovered them by eliminating every possible cause. ^_^
[8~{} Uncle Arc Monster
You have all laid out some serious detective work ahead. Nice to know that there are lots more things to look for. I think I have a pretty good idea where to start looking.
Someone on a electrical website suggested taking the AFCI breaker and mounting it on a cord so I can plug it into outlets on the circuit and see if it trips -- at least that way I can keep the circuit live on the old breaker while testing for the location of the arc fault. Someone else said the breaker wouldn't trip if it wasn't under load, even plugged into a circuit with an arc fault.
We did replace one outlet -- I pulled it from the wall while live (don't tell on me!) and I saw sparks coming from the internals of the outlet. Replaced it, but that didn't solve the problem. I guess like I said elsewhere it is time for "grunten and cranken." Cripes. I am sorely tempted just to leave the old breaker in place and remove all the heavy loads from the old circuit. Running two new grounded outlets, a real bitch in old houses like this, doesn't seem nearly as much work as has been described in locating the fault.
What I really need is some way to remotely switch back and forth between the old breaker and the new AFCI one so I can see the effects of removing loads one at a time. I guess the reverse of that is to disconnect all loads, power up the circuit and if it holds, add back the loads one at a time until I find the mutha frakker that is doing this. If the breaker even holds, that is. If it doesn't that means doing what has already been described by Don and others. Digging the wires out of the wall. Not gonna happen. If I am going to tear up plaster, it is going to be to install new grounded romex.
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.
Start by unlugging EVERYTHING. If that fixes it, you are lucky - it's likely not IN the wall. Then plug things in untill it trips. If unplugging everything doesn't fix it, start disconnecting outlets.
Remember the arc can be either a series arc or a parallel arc. A series arc is an intermittent open in nature - a parallel ark is an intermittent high impedence "short". Those can burn the house down without a load attached and are the difficult ones to trace. Sometimes an old am transistor radio can detect the crackle - (couls even work for series arc - I'd give it a try anyway!!
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!
Got one today based on a suggestion from a web forum. So far all I know is the wire from the troubled circuit leaves the box and heads right into a bundle of other wires heading into the attic. I wasn't able to trace to anything I didn't already know by inspection when the breaker's off. Crap!
More importantly, this is one of the old "ragwires" and I don't know how much more connecting and disconnecting from the breaker it is going to stand. I may have to pigtail a wire from each of the two different types of breaker and switch between them using heavy duty insulated alligator clips on a jumper wire. I don't want to add a broken wire to my other troubles.
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 hurry.
That is generally what I am doing but I need to run extension cords from other outlets to keep the router and other essential items running while I test. What a cluster frak.
What is this? There is more than one type of arc monster to deal with? Say it isn't so!
They all seem to be difficult to trace. I assume a partially inserted plug causes a series fault while a nail through the wire causes a parallel one. More reading to do.
I wish this stinker just worked when we turned the panel back on. He charged me $750 for the panel replacement (20 breakers in all) and it took 6 hours. That seems to be a pretty good price for panel replacement and he did a very neat job. This AFCI thing was just circumstances beyond anyone's control. As pissed off as I am by all the extra work that is involved, I suppose I should be thankful that the AFCI discovered the arc fault, and not the firemen.
Now I feel like a Marconi operator listening for the Titanic sinking!
FWIW, I took the old main breaker out and it was certainly heat and corrosion damaged. Very interesting how they put those things together. I think it would have lasted another 20 years, though, because none of the contact areas were very corroded. The problem was the broken set screw and though we patched around it, the only way to repair it was to replace it.
Still, I am happy we replaced it even though my wallet is not.
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?" "Yes." "Lucky *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!!)
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