Intermittent tripping breaker

Have you tried meggering the circuit? Checking the insulation of the wiring. You will need to unplug everything to do this.

What do you mean "meggering"? Do you mean:

1. Unplug everything from the circuit (including taking all bulbs out of the fixtures.

1. Disconnect the hot wire at the panel

1. See what the resistance is from hot to neutral and from hot to ground.

Is that the idea? And make sure that the resistance is really really high, right?

--- M.

Soundz to me like you have a Ghost taunting you }:-)

Questions: What gage is the wire that is attached to the circuit breaker ?

What gage is the wire throughout the defective 20A circuit?

• Is there a trough or splice box where several circuits converge past the panel & before the branch circuits ?

Reads like you were thorough enough, but You've missed something, for sure.

That sort of problem occurs alot when a)you have an overload, or, b) a (Ghostly) bad neutral connection somewhere.Maybe the owner just likes having you around opening boxes & testing wires }:-) Ask her if itz okay if you bring in an Exorcist to look into it ?

Roy Q.T. ~ E.E.Technician

You have the basic idea. However, the resistances involved are normally so high (tens of megohms) that your garden-variety meter, powered by a

1.5 V or 9 V battery, can't measure them. A meter called a "megger" is designed to measure high resistances by applying a voltage of 500 to 1000 V or so. Some of them generate this from a normal battery and some have a hand crank you can turn.

Also, I would disconnect all three wires (hot, neutral, ground) at the panel, and try all three pairs (hot-neutral, hot-ground, neutral-ground), before trying to measure resistance this way. If you do this, it won't hurt anything to try it with a normal meter, but don't be surprised if the meter reads "infinity" on all three readings.

Some other ideas... when you replaced the breaker, it was with a brand new breaker, right? Something else you might try, if you have another breaker of the same rating in that panel, is to swap the circuits between the two breakers. If the same breaker blows, it's the breaker; if the other breaker blows, it's the circuit.

Does it seem to be correlated with walking in a certain part of the house, or closing a certain door, etc? Movement of the house structure might be causing wires with marginal insulation to contact each other.

Failing that, since it seems like you can follow the circuit pretty well, you might work along the chain, disconnecting parts of the circuit, like you did at the first junction box. After a while you can probably isolate it to a certain run of cable. At that point you can either yank that section of cable out to satisfy your curiousity, or you can disconnect the bad section and wire around it with fresh cable.

Matt Roberds

Check for corrosion or oxidation in the circuit breaker panel where the circuit breaker snaps onto the buss bar. You should turn off all power to tbe panel before doing this. A high resistance connection will heat the breaker and cause tripping.

Bill Kaszeta Photovoltaic Resources Int'l Tempe Arizona USA snipped-for-privacy@pvri-removethis.biz

Say Max it just occured to me: if you haven't check out any motorized appliance Plate current waterpump, washer, fridge etc. the Overcurrent Protection on their branch circuit Circuit Breaker to which it is connected must be rated 115 -125% the branch circuits total load so you must take that into condieration when estimating your current values versus your circuit breaker/conductor ampacity.

I think someone had mentioned it, when any motorized appliance or machine kicks on more than the running current is drawn and that may be a factor in your troubled circuit.The Ghost in The Machine];-) =3D> Not all that connected to it (apparently under current values) but a Temporary Intermitent Overload created by an appliances Random kick off taking it past the circuit parameters.

=AEoy

The wire is #12, and it's a 20-amp breaker, so that's correct. As for any trough or splice box, no. The wire goes up out of the panel, into a crawlspace (which I've been in, and I can see all the wires coming up out of the panel). From there it goes down a wall, and into the basement, where I can see it. About 3 feet later, it goes to the first junction box with the pullchain fixture on it, and from there, it goes everywhere else in the basement that this circuit feeds (2 lights, and 2 outlets, one of which has the oven plugged into it).

So, except for the 8 feet or so of wire going down that one wall, I can see every inch of the wire.

As for an overload... even with this circuit fully loaded, there could only be about 4 amps of current on it (just a few lights and the oven control valve.

I also plugged a big toaster oven into one of the basement outlets to see if anything "exciting" would happen when the circuit was under heavy load. Nothing happened (except the toaster oven came on and the elements heated up).

Just today, I did note that the ground wire from the main service cable inside the panel wasn't quite tight (where the big cable goes into the big screw on the bus bar). I tightened this. About 10 years ago, we had a problem where the main breaker tripped a couple of times over a few days, and I noted then that the mains screws weren't quite tight (&@#@%^$ aluminum main wire!). No, there is no other aluminum in the house. Just the drop from the street pole.

Anyway, after I tightened it, the breaker didn't trip all day today until just about an hour ago. I really thought I had found it. Although I did wonder why the loose ground would affect THAT particular breaker.

--- Max

Roy Q.T. wrote:

Yeah, I looked up "megger" on the web. But I have a good-quality meter that can measure up to

10 megohms. Besides, if the resistance is a full megohm, I doubt I have an insulation problem.

About the breakers... First, I swapped the wire over to another 20 amp breaker that was unused in the panel. It still tripped. However, wondering why there would be an unused breaker in the middle of a panel, I worried that maybe that one was no good (that's why it's unused) and they left it in there because they didn't have a blank and didn't want to leave a hole. So, I replaced the breaker in the original spot. And it still trips. The replacement was NOT new, though. Bulldog Pushmatics aren't easy to come by --- although I have since found a few places that have them for about $25 a piece.

I think you're right. If I swap it with one of the existing 20-amp breakers that isn't tripping, that will eliminate the breaker from the equation once and for all.

I haven't been able to correlate it with ANYTHING. It trips at all times of day or night. It doesn't seem to matter whether the house is warm or cold (furnace running during the day, or running less overnight). It doesn't seem to be affected by any activity (like being upstairs, downstairs, etc).

Seeing as how it tripped with the lighting branch disconnected, or the oven receptacle branch disconnected, but not with BOTH disconnected, it certainly seems like it has to be the main wire from the panel, or something really weird in the house that's feeding voltage back onto this one circuit.

I should have mentioned that although the house was rewired in the 1970s (no, it's no aluminum wire), it is over 100 years old, and there are still some unseen sections of knob and tube wiring in it, not to mention some insane wiring maneuvers that I probably haven't found yet (i.e. I've caught a few potential disasters over the years and fixed them, like 3-wire outlets with no connected ground, or a 20-amp circuit that went IN to a junction box but came OUT on a branch without the ground being connected, and my personal favorite, an extension cord in a cabinet that went into the floor, only to be wire-nutted onto the romex under the floor (no box, no NOTHING).

However, and this is key, this particular circuit is nice clean new NM rubber-jacketed wire over its whole length. It does not have any potential for this other type of junk being in it.

Thanks, Max

snipped-for-privacy@worldnet.att.net wrote:

Yup. Been inside every box. Nothing was loose, and nothing was touching anything. I even ran the circuit with every box pulled open (the porcelain pullchain fixtures pulled down out of their octagon boxes, and the receptacles and switches pulled out). Still tripped.

I wondered about the clamps, or maybe even the steel staples that anchor the cable to the overhead joists in the basement. I'll have another look at those.

Of course, this would be a lot easier if the damn thing would just short out altogether. Then I could disconnect things and find it. But it will run for 8-10 or more hours without a hiccup.

Thanks, M.

Phil Munro wrote:

Not a bad idea. But since I've already swapped out the breaker, I was looking for that. Although this panel is old (from the 1970s) the inside is clean as a whistle. There isn't a blemish or spot of rust anywhere. The busses are clean and bright.

thanks, Max

Bill Kaszeta / Photovoltaic Resources wrote:

I have puzzled and puzzled about this. There is nothing motorized on this circuit. However, could a motor on ANOTHER circuit cause this? I keep wondering if the circulating pump for the hot water heating system could cause this (although that thing turns on and off a hundred times a day, and I've never caught the breaker tripping right when the pump goes on or off). I keep wondering if that motor could send a spike back to ground when it kicks off. But even if it did, I don't see how that would hit this circuit. The wiring isn't anywhere near each other (even though it's in the same room in the basement), and the spike would go back to the panel and to ground. I'd also expect it to affect other circuits as well.

Remember, no other circuit in the whole house is misbehaving.

-- M.

Roy Q.T. wrote:

As someone has already said your good quality meter will NOT do what a MEGGER will do. A Megger will put 500 or 1000 volts between the test points and find breakdowns that the 1.5 or 3 volts in your good meter will never find. Do not forget to remove all the power before testing.

Aside from all that you do seem to have a strange problem which after acutally changing the breaker will only be solved by breaking off every separate wire in that furher junction box till one of them proves to be the culprit.

pardon me: it doesn't seem like a motor Kick (On) overrload };-{) it does sound puzzling like you say. I came across a tuff pony like that once i'm not sure but I may have just rewired the affected zone.

(*) There could be a Break in one of the New Conductor (sometimes handled too Roughly) that when energized is drawn together at the fracture, and when the circuit conductors relax (they do expand & contract) the fracture again disengages Causeing it to Trip ... you'd have to take a chance and rewire the affecting or affected length....test: disengage everything you know is good and put a temporary hookup to it (for the tenants convenience) from a circuit breaker in known good service spot and see if it will trip again (& from what configuration).[you probably have it narrowed down already] but, narrow down your branches until you isolate the affected conductor cable eliminate it, and redirect New cabling to the splice box remove the tempt hookup and VVuala ..... i hope :-)

just in case that test fails: recheck all your Buss lugz in every panel, the power company should attend to their meter you can say it's suspect & have it opened & check it with them.

Electrical Circuits & Equipment are known to stop messing around when I enter a dwelling };-) with practice & determination (which you don't lack) they'll soon respect you too.

=AEoy

ps: don't tell me ? it's stranded & can't fracture like that.....

Only guys I know have Meggers are Utility Linemen/Workers (if all fails call em) & Cable TV Trackers. If that was the only solution my goose would be cooked a long time ago. =AEoy

max wrote in news:6sM%d.6586$uw6.1896@trnddc06:

Since you have disconnected the feed from the first junction and it did not trip the breaker, the problem has to be further down the line. Get a suitable length of 12/2 w/g romex for a test wire, unhook the feed at the first junction box, hook it into your new piece of wire. Go to your second box on the run, unhook the feed from the junction box coming into that box, hook your new wire in there temporarily. Wait for a trip. Keep jumping out one isolated leg (run) of the circuit at a time with your test wire. You will find your problem. There is an obvious problem (short) somewhere, and waiting until it becomes evident by itself may leave you homeless :/

First, me say a big THANK YOU to all of you who have contributed your advice on this ugly breaker-tripping problem. I very much appreciate it.

Here's where it stands.

Recall, the breaker has been swapped with another one that happened to be unused in the panel, and with another one I had, which was not new. This didn't help.

The feed from the panel goes to a junction box which feed only two branches that are plainly visible in basement ceiling. The breaker has tripped when EITHER branch is connected by itself. The only time I have seen it not trip is when the main feed wire was just capped off with wire nuts at the first junction box.

I have tightened and checked everything in the main panel, including a slightly-loose screw on the main ground from the service cable.

Now:

1. All branches disconnected at the first junction box, which I did before, and which many people have suggested. But a pigtail is spliced onto the feed wire there. I had tested it before by disconnecting everything and just capping off the feed wires, but that doesn't put any load on the circuit. It could be that the wire from the panel is bad after all, but only shows trouble if there's some load on it. So now I've got a light bulb on it all the time.

1. I swapped the circuit in the panel with another breaker that is known to be working (had never tripped in its life that I know of. This eliminates the possibility that the spare breaker I tried in the panel was bad AND the replacement breaker I put in was also bad (it wasn't new).

There's one more tidbit that might mean something to one of you out there. Let's call the problem breaker #6. Recall that the panel feed goes to a junction box, and then 2 branches go out of there --- one for some lights, and one for an outlet. I noticed today that on the lighting branch, I can read 3 volts between the hot wire and ground even though this branch is completely disconnected. I went down the panel, turning each breaker off/on in turn, and found that the 3 volts disappears when ANOTHER breaker is off (#12, just for conversation's sake).

Cable for circuit #12 does go through the basement, and in a few places it is pushed right through the same hole in the floor joists with the cabling for circuit #6 (very bad practice, I know... wasn't my handywork). In fact, the two cables were jammed really right through the same hole in 2 spots. It's also true that if I put even the slightest load on this branch cable, (like an analog VOM), the voltage disappears. It looks to me like it's an induced voltage caused by the cables for the two circuits being so close together.

As I plug things in or otherwise change the load on circuit #12, the induced voltage goes up or down (but never more than 3 volts).

I drilled some new holes and rerouted the #6 cable so they are separated. After each place I did this, the "mystery" voltage dropped, until now it's down to about 200 millivolts. And no, I didn't find even the slightest nick or distress on the cables where I separated them.

The breaker was tripping even when this branch was completely disconnected, so this can't be the problem.

But... is this normal? Is it anything to worry about?

--- Max

And to tell you the truth, I'm beginning to think this is one of those problems that's being cause by MORE THAN ONE problem at the same time. I've had a few of those in my life, and they are always the worst.

Please remind me (us?): the breaker is a non-GFI standard 20A (or

15A?) pushmatic breaker? And > First, me say a big THANK YOU ...

Standard 20A non GFI Bulldog Pushmatic. The feed goes out of the panel, to a junction box with a pullchain light on it. From there, it goes out to only two branches. One is an outlet, and the other is just some lights in the basement (all octagon boxes with porcelain fixtures on them).

The breaker will hold anywhere from 2 to 12 hours (approximately). Usually, it holds for 6-8 hours.

When it trips, there is no way I can see to "reset" these like a "normal" breaker( i.e. a Square D, where you switch it all the way to the "off" position, and then turn it "on"). These are just push on, push off devices. The only thing you can do is "push" it, and it clicks on (and "on" shows in the little window).

If there is some special way I'm supposed to reset these, I'd sure like to know about it.

Yes, while it's on, I definitely have tried pulling on things to see if I could expose a weak spot, bad connection, or short somewhere. I've had all the fixtures down out of there boxes, on, and bent and twisted them, and pulled on the romex cabling in the ceiling everywhere I can touch it. Nothing ever happens.

Colors: Yes, all the blacks are hot, all the whites are neutral, and all the bare are ground. I've checked every one, in every single box, including the panel, with a meter. I've checked between hot and neutral, hot and ground, and neutral and ground. Everywhere I get Hot-Neutral (about 120v) Hot-Gnd (about 120v) Neutral-Gnd (zero, or a few millivolts at most) (All except for the one whacky branch, where I saw the induced voltage from circuit #12.)

About another circuit interacting... that's kind of where I was going when I found the induction voltage from circuit #12. I put a meter on the circuit #6 hot wire and my wife cycled all the breakers. But the only thing I saw was that 3 volts, which fades the further apart you make #6 and #12 cables.

On making this up... You can rest assured that I certainly am not. Problems like this are about as much fun as mystery plumbing leaks (don't get me started!) And it's been one terrific headache. I'm just glad it happens to be on a circuit that doesn't cause any disasters when it trips (i.e. it doesn't shut down our furnace or refrigerator in the middle of the day when nobody is home!)

I'll let you know when I know something. Since I put everything back together this afternoon after separating the wires, I hung that pigtail light on the circuit (with the rest of it disconnected) for a few hours, and nothing happened. Now, I've got the branches hooked back up, and I did swap the breaker with a known proven working one from another circuit, so I'll know for sure whether the breaker has anything to do with it.

Thanks, Max

Phil Munro wrote: