The first "test" I did was to replace the breaker -- with one that has seen
*no* use.So, while flipping the breaker on and off a few dozen times a year *may* fatigue the mechanism, it's not the cause of our current problem (unless the replacement breaker happens to be defective from the factory).
If it is a clump of moist material, you may be cooking the moisture out a little with the first attempt. I am not a fan of the "inrush" theory of GFCI tripping. (or most other myths about what trips them) This is a simple comparison of the current between the hot and the neutral through a buck wound transformer. If you really think it is an overcurrent situation, plug it into a non GFCI circuit to test it
I have lots of GFCIs around here and it is not unusual to have one that tripped to hold after resetting a time or two. In the end, I always find a fault somewhere, usually something that is getting wet.
What happens if the breaker is already on and you just plug in the lights?
The breaker trips. This is one of my least favorite ways of testing as it means a trip all the way around the house to reset the breaker... By contrast, turning the breaker on with load attached gives me the same feedback -- and, I'm right there, ready to turn it back on, again.
On grumbling about this ("yet another chore on my list") to SWMBO, she claims she took the toaster oven outdoors some months ago (WTF?) to "prepare" something and it wouldn't work, either.
I.e., that removes the extension cord and lights from the calculus.
I've removed the breaker from the scenario.
I can (with a bit of work) remove individual duplex receptacles (leaving the balance of the wiring intact) on the theory that something is *inside* one of these (leaf cutter, etc.).
[I've started doing this hit-or-miss but need to do so in a more methodical manner so I can draw conclusions from the observations]I can (with a lot *more* work) isolate sections of the wiring (hard to imagine that being an issue -- it's not routed anywhere that is likely to see abuse, infestation, moisture, etc.)
I will notice how quickly the problem reappears when I turn the lights off a bit later this morning -- bulbs having been lit all night (warm filaments, warm lamp bodies, etc.)
+1
I also don't think the inrush current on 700W on lights could trip a 20A breaker. If it could, seems we'd have that problem all the time. 700W is only 6A worth of lights. I would think it's more likely something related to a fault, but why it would not happen on the second attempt, IDK.
I'm remembering the customer who called. The furnace tripped the breaker. So, she reset the breaker a couple dozen times, till the breaker stayed on. Still won't work.
I find the first problem was a $65 shorted blower motor. Second problem was the $250 circuit board that fried cause she kept sending power surges through it.
Then, what is "rehydrating" the material for the *next* time it trips? No rain, here. Low humidity. No plumbing anywhere nearby.
That assumes the overload characteristics of the non-GFCI breaker are identical to that of the GFCI breaker. I have yet to find any documentation that calls out specifics -- for the GFCI breaker *or* the non-GFCI breakers located in the same panel!
This can't be the problem. Lights have been on all night. "Unplugged" them (i.e., don't muck with the breaker).
Wait *1* second and plug in, again. Lights come back on (i.e., breaker does not trip).
After a few seconds, unplug again. Wait 10 seconds and plug back in. Again, lights come on.
After a few seconds, unplug a third time. Wait 2 *minutes* and plug back in. Breaker immediately trips.
And, plugging the extension cord into a non-GFCI (inside the home) outlet -- keeping exactly the same amount of cord "wound" on it's spool as before -- does NOT trip *that* breaker.
I.e., the only thing that has been isolated as a result of these tests is the wire inside the walls and the actual receptacles; when that stuff is "in circuit", the breaker trips (either when turned on *or* when a "cold" load is plugged into it)
I'll try to remove all of the OTHER receptacles (places where things can infiltrate the wiring) and repeat the original test.
Then, replace the receptacle in question.
Then, move the load to a different receptacle.
Beyond that, I'll have to start opening wire nuts -- not something I like doing with #12AWG :<
On 12/02/2015 12:08 PM, Don Y wrote: ...
That's got to be a thermal problem in (probably) a particular lamp...eventually it'll burn out and let you isolate it or the base itself will fail.
Unplug the three strings from the extension cord. Leave cord exactly as is. Take three *other* "identical" strings out and wire them in exactly the same fashion as the first set-of-three.
Turn on breaker. Trips immediately. Let it reset and turn it on a second time. Holds.
Walk around house to return to the point where the extension cord is plugged in.
Unplug. Wait a few seconds. Plug back in. Breaker trips.
(No, I'm not going to keep repeating this test to see how long it takes for the load to "deteriorate" between power applications. The fact that it tripped suggests the problem is not in the original three strings of lights -- or, coincidentally ALSO happens to be in the OTHER three strings, as well. And, no, I'm not going to drag out a third set of three... or a fourth set of three... :> )
...
...
Hadn't seen the duplicated test result...
I'd stick with the thermal issue and I'd suspect the cord if it's one of those w/ the indicator lamp built into the plug.
Did you ever isolate whether there were any other loads on this circuit besides these two (I think were mentioned early on?) exterior receptacles?
Seems that the surge current of all those bulbs is just a bit too high for the breaker.
So here's a question...
I assume the lights in question are small incandescent bulbs.
Are they the type that you can unscrew one and all the other bulbs stay lit (indicating they are wired in parallel) or are they the tiny bulbs that if you unplug one bulb many others in the string go out as well (indicating that they are wired in series)?
Mark
The only (intentional!) load on the circuit is these (or "those" -- depending on whether you refer to the original 3 or the replacement 3) 3 strings of lamps.
I.e., in a theoretical scheme, it's just a long wire with a bunch (5) of duplex receptacles hanging off it, fed through a circuit breaker (which has been replaced with an "unused" GFCI).
The fact that the different strings don't appear to make any difference to the result *suggests* it's not in the "load".
The fact that a different GFCI doesn't appear to make a difference tends to rule that out.
This leaves outlets, wiring and extension cord.
The fact that lights plugged into extension cord doesn't cause a problem on another branch circuit suggests the cord MIGHT not be a problem (it could still be "leaky" and the non-GFCI doesn't notice that).
I can remove receptacles from the wiring (a bit of a hassle to remove the "outdoor" covers, remove the receptacle, then remove the two conductors -- I can leave the safety ground as long as I ensure the receptacle is "dangling freely")
Isolating portions of the wiring gets to be a bit more involved; instead of "daisy chaining" through the second set of contacts on the receptacles, I tie the upstream and downstream wiring together with wire nuts and run a pigtail off to the receptacle. This ensures the receptacle is not "in series" with the downstream devices.
But, today is shopping day. So, instead of using the daylight hours to troubleshoot the problem, I'll waste them running around buying "stuff". (sigh)
In the past, there were 3 times as many bulbs in place without a problem!
IIRC, they are 9W, miniature base.
The bulbs are wired in parallel. I.e., the two conductors pass *to* each socket and continue onward to the end of the string. At that point, an outlet is located -- which feeds the next string in the "series" (as in "sequence").
The wire gauge is such that you aren't supposed to daisy-chain more than two additional strings onto any string in the "series". Hence the reason we use a cube tap to start a new "set".
Running each string to a single feed point (from the extension cord) greatly complicates the logistics of getting lamps all the way around the tree. And, makes the end of the extension cord a crowded place...
They seem to just be a regular breaker with a GFCI manual trip mechanism built in.
You may just have a bad breaker.
wow
so maybe your breakers aged... (I'm serious, they do age)
or you changed extension cords to a heavier guage?
or there is other load in another outlet on the same breaker
I would as a test change to a non GFI breaker to eliminate that possibility.
I didn't see the naswer to the 2 out of 3 question, what if you use 2 strings instead of 3?
Mark
5 breakers located "in a row" in the electrical panel. One has never been wired to anything (that's the breaker that I used to replace the one in question). The other three are reliably servicing kitchen counter outlets and bathrooms. All see regular loads. None have ever tripped (for overload *or* ground fault)
Same extension cords that have been used in the past. If this one wasn't actually used on *this* tree LAST year, then it was used on one of the OTHER trees.
Nope. Only 5 (duplex) outlets. Four of them along the back of the house, the fifth around the side.
Moving to a non-GFCI *circuit* yields reliable operation. What I haven't tried is swapping the GFCI breaker with a nonGFCI breaker. That requires a bit of rewiring and leaving that other branch circuit idle while testing.
[I'm comfortable working with electricity -- but in the panel, there's nothing between you and "sudden death" :> I'm not going to flip the main breaker just to make these sorts of breaker changes]Should I then move to 1 out of 3? And, from that, 24 out of 25 bulbs? Then 23 out of 25? etc.
The fact that this is just a MODEST load suggests the problem has to be noticeable. If I was pulling 2200W, I could imagine some merit to downsizing the load to 2000W -- or even 1000W! But, at 675W, my microwave oven draws that! My *hairdryer* draws more than that!
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