GFCI's

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On 12/03/2015 10:45 AM, Don Y wrote: ...

But have you done the simple expedient of swapping out extension cords yet?
...

I repeat--
But have you done the simple expedient of swapping out extension cords yet?

Just swap a standard breaker into the slot in the box.
--


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On 12/3/2015 11:32 AM, dpb wrote:

Different extension cord makes no change in symptoms.

(sigh) Sorry, but *I* can make a giant list of all possible combinations and permutations or circuit breakers, circuit breaker TYPES, extension cords, number of strings, WHICH strings, internal wiring, ambient temperature, time between applications of loads, etc. ...
then, try ALL of those variations to find the one(s) that work and don't.
That's not troubleshooting. That's what (inept) mechanics/plumbers/PC technicians/doctors/etc. do day to day:
"Well, let's try replacing the battery to see if that's the reason your old battery died..."
(weeks later) "Hmmm... I guess it wasn't the battery as that NEW one has also died! Let's try replacing the alternator!"
(weeks later) "Hmmm... what are the chances that the new/rebuilt alternator was defective? Maybe the cable harness is bad..."
I'm looking for a *reasoned* approach to a particular cause and effect: if *this* is the underlying problem, then this experiment will serve to isolate and identify that as the cause.

Do you understand the difference between "a standard breaker" and a GFCI?
A standard breaker has two connections: the power from the distribution bus bar (usually a "snap on") and the *wire* that feed the branch circuit ("load"). The branch circuit picks up it's neutral and ground connections from a common connection point shared among all branch circuits (as well as the "AC line input")
A GFCI breaker has *four* connections: bus bar, load, NEUTRAL and NEUTRAL PIGTAIL. I.e., the neutral wire feeding the branch circuit connects to the breaker, NOT the neutral connection point.
Assuming you remove the GFCI and LEAVE IT DANGLING by it's neutral pigtail, you still have to route the neutral for that branch circuit up to the connection point for ALL the neutral's in the panel. It's not "right next to" the breaker, alongside the "hot" connection to the breaker!
Would you like me to also replace all of the RED lights in the strings with BLUE ones? Maybe BOTH extensions are defective? After all, both have been out in the same environment... maybe they've both developed the same fault? A fault that HEALS ITSELF when the lights have had a chance to warm up??
Maybe both GFCI breakers have failed in the same way -- despite the fact that the other three located within inches haven't?
Sorry, I don't mean to sound pissy but "try this" is not what I'm looking for. I want to approach the problem logically not willy-nilly. I'd hoped someone might have *definitive* information of problems like this instead of a litany of hit-or-miss attempts. I.e., an explanation that reconciles ALL of the observations I've posted.
(sigh)
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sorry but that is a part of troubleshooting Swapping around parts that you already have can be a very efficeint troubleshooting technique.
If we told you to go out and buy all new lights and new extension cords and new breakers and replace them all, that would not be troubleshooting, that would be shot-gunning.
If you prefer a more analytical approach, then go out and buy a dual trace oscilloscope, clamp on current probe and other assorted test equipment and we get then gather enough data to decide exactly what the problem is without swapping parts.
Sounds like we have nothing more to offer you in the way of help.
Be sure to come back and let us know what the answer turns out to be.
Mark
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On 12/3/2015 12:36 PM, snipped-for-privacy@yahoo.com wrote:

No, that's the lazy approach. That's the way auto mechanics start swapping things (charging you for each "new replacement" -- even if it didn't FIX the problem) out until they stumble on the "solution". Do they ever work their way backwards, undoing all of the other (faulty) changes they introduced along the way to definitively identify/verify that the "final change" was, in fact, the real reason? Do they swap the "bad" part back in to verify that the problem manifests, again?
This is just a lack of deductive reasoning capability. I see it in how folks troubleshoot electronic designs, software, etc. all the time. "Let's try this..." Then, if the device/program *appears* to work, they content themselves with having "fixed it" -- with no basis for belief that it is, in fact, (permanently/actually) "fixed".
"Well, it's working NOW..."
I guess in grade school we were taught "The Scientific Method"; form an hypothesis, construct an experiment to test that hypothesis, then apply it and verify the results.
And, you can run that process forwards or backwards, with predictable outcomes in each case.
E.g., note that when I unplugged the lamps this morning and re-plugged them, they didn't trip the breaker. Yet, plugging them "cold" caused an instant trip. So, modify the experiment -- wait *10* seconds before re-plugging. Then, 2 minutes.
Ah, now I have new information to assist in formulating a theory (what, in the circuit, can "account for time"?)

You'll note I lamented the loss of my HiPot tester, up-thread??

Agreed. I'll return to my original plan of diagnosis.

I'll look into it this weekend. The lights won't be needed, again, for several days so I can spend my time on other things that are more pressing.
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On 12/03/2015 3:08 PM, Don Y wrote: ...

A thermal effect as postulated previously.
...

...
_IF_ you did still have high quality test gear, I'd tend to agree with your attempt at more esoteric trouble-shooting. Lacking that, the likelihood of placing a measurement at the right spot with the facility to catch the event is approaching zero...
So you might as well eliminate the one common component from the problem before continuing down all those various ratholes you've previously enumerated...
--


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On 12/3/2015 2:26 PM, dpb wrote:

No, the logical approach is to imagine some agency (weather, infestation, phase of the moon) that has asserted itself on the "system". Then, think of what sorts of "changes" it could have made THAT WERE NOT PRESENT, PREVIOUSLY.
E.g., leaf cutter wasps laying eggs *inside* receptacles -- given that I know these exist, here; water infiltrating a fixture (nope, no water sources); something chewing on insulation (unlikely); etc.
I.e., look for a simple explanation that ties all the observations together, consistently. Yeah, it could be all my bulbs have a problem; it could be all my extension cords; all my GFCI's; etc. But, it's not LIKELY that all that stuff happened AT THE SAME TIME. I'd buy it if I had a problem with one string of lights last year, another the year before, etc.
OTOH, something affecting *one* of the receptacles would make sense -- *if* a reason for the other observations ALSO made sense!
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On Thu, 03 Dec 2015 14:08:34 -0700, Don Y

Since you are not paying for things you try that is not really a good analogy but without the right test equipment, eliminating things in the path is probably the only real way to go.
If I was really willing to "diagnose" this I would get a device type GFCI, Disable the trip mechanism and look at the output of the differential amplifier with a scope as I plugged in the lights, cords etc looking for the one that is the offender. You could calibrate your result using a pot and introducing a known fault value. My bet is you will see this thing cruising in the 3-4 ma range so any little glitch pushes it over.
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On Thursday, December 3, 2015 at 7:47:53 PM UTC-5, snipped-for-privacy@aol.com wrote:

I always start on the path of trying to fully diagnose the problem instead of swapping parts. But anyone who has worked on cars has sure had many times where they wished they had the dealers stock of parts to try swapping something that is easily swappable to see if it fixes it.

Agree, that's the problem and why you're left with swapping. To conduct the required tests is going to require some advanced gear that homeowner's typically don't have. Even if I had it or had access to it, I wouldn't waste my time trying to figure it out.
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On Thu, 3 Dec 2015 17:16:03 -0800 (PST), trader_4

When I was fixing things for a living, my first question on a support call was asking the guy who was working on it "Can you draw a circle around the problem"? (in an acre of computer room floor, that may not be as simple as it sounds)
Until you know for sure what box is failing, you really have to back up and reassess.
It was surprising how many times that just getting your head put of the box, turned a light on and got you on the right track. Isolating the problem does not mean simply throwing parts at it. You should learn something at each step.
In Don's situation,. I would start with a configuration that doesn't fail and keep adding stuff until you break it. Drag a known good space heater or heat gun out to the end of that extension cord and try that, bearing in mind, the fault could be on the neutral and that will not fail without a load.
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On 12/3/2015 8:25 PM, snipped-for-privacy@aol.com wrote:

There are no configurations that "don't fail" -- except the configuration where there is no load present (and, thus, no need for power!).
My approach will be the opposite: remove things until it starts working.
Recall, everything worked last year. The extension cords and lights have been stored "indoors" for all that time. OTOH, the outlets have been exposed to the elements for the ~9 months (including a Summer and a Monsoon) since then. So, any "changes" are most likely manifest in those items!
Wiring inside the block wall is likely not at risk as it is safely hidden away (unless something likes chewing on vinyl!)
First, verify SWMBO's assertion that the toaster oven resulted in a similar behavior. If that's true, it *tends* to rule out the lights and the extension cord as possible problem areas (no guarantee, there, as they could have other problems, as well). Then, reattach the lights as the "nominal load" -- cuz I have lots of experience with them failing (I don't want to end up with a situation where things SOMETIMES work and that confuses any deductions made later).
[The idea of leaving an item used for food prep outside just doesn't appeal to me! :> ]
Explore the upper limits on what the breaker will HOLD. If it trips (when it would otherwise have held, based on prior observations), I have another data point regarding the circuit's performance. Is any loss of capacity a likely effect of aging? Or, is it dramatic enough to suggest a fault, somewhere (keeping in mind that I'm using the replacement GFCI, presently). Can a regular (20A) branch circuit carry the same load without incident? (those breakers are OLDER, yet!)
Then, open all the Jboxes and have a peek inside. Any signs of "wildlife"? Moisture?
Beginning at the box closest (electrically) to the panel, look at hot-neutral, hot-ground, neutral-ground voltages under that fixed load (with breaker in the "holding" state). Any IR drops should scale linearly; regardless of how much wire there is between Jbox #X and Jbox #Y, there should be an identical amount of neutral, hot and earth conductors! I can do this from the exposed side of each receptacle -- no real effort required.
Then, start removing receptacles (in the hope that something may have set up shop INSIDE one). At the same time, examine the contacts on each: anything loose? Any signs of oxidation/corrosion?
Any changes in voltage readings when probing conductors instead of outlet contacts?
Ultimately, I'll have to remove the outlet into which the extension is plugged.
If this turns up nothing, start moving the load upstream. And, after verifying operation at each such point, isolate the downstream portion of the branch circuit (open wire nuts).
Eventually, I'll have a wire in the wall that connects the GFCI to the *first* -- and ONLY -- receptacle.
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On Thu, 03 Dec 2015 23:22:41 -0700, Don Y

So if you plug something into the outlet right next to the house it fails?
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On 12/3/2015 11:30 PM, snipped-for-privacy@aol.com wrote:

(All of the outlets are "on" the house; presumably, you meant "closest to the electric panel"?)
I've not tested each of the 5 outlets. They are spread over the length of the house -- as well as around the side. I.e., I'd have to *lengthen* the extension cord to reach them all.
I don't plan on continuing the "willy nilly" approach of jumping to "try this", "now try that". Instead, I will approach the problem in a more structured manner -- so each result adds to the data set in a more organized fashion (instead of taking pot shots in different areas).
But, that will wait until at least the weekend. I have many other things that need to get done in the short term and the forecast suggests I've got at least a week before temperatures begin to approach the lows that are troublesome...
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On Fri, 04 Dec 2015 05:00:33 -0700, Don Y

You can't get more "structured" that just plugging a comparable load into the receptacle that fails (without involving extension cords tree lights etc)
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On 12/4/2015 8:28 AM, snipped-for-privacy@aol.com wrote:

What if the nature of the load has an impact on the results? E.g., say I plug a large power supply for that has an insane turn-on transient in but idles at just a few watts (switching losses). Smaller load but bigger turn on transient.
Or, drag out a longer spool of wire to use as the extension cord?
Or, try the toaster oven on one and lights on another?
Don't add variables to the analysis. Just come up with a consistent test strategy and apply it consistently.
E.g., the second set of 3 strings that I dragged out to mimic an "equivalent load" (as the first set that are presently IN the tree) is only conceptually an identical load. Making observations with one set in one case and another set in another case isn't apples<->apples. Even though it might (and quite probably is!) appear to be so.
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On Fri, 04 Dec 2015 13:12:26 -0700, Don Y

For the purposes if this discussion, a hair dryer would do just fine. If it trips, you know you have a problem in the wall or receptacle string. Then try it at the end of the extension cord. If still no trip, there is a problem with your lights.
The idea that an incandescent light will trip a GFCI in normal operation (no faults) is ludicrous. That tiny surge while the filament is heating up is well inside the trip curve of any breaker I have ever seen. It would certainly be less than the heat up time of a hair dryer element.
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On 12/4/2015 1:43 PM, snipped-for-privacy@aol.com wrote:

You've not been paying attention to the numerous "experiments" I've already conducted.
E.g., different extension cord --> trips. Different light strings (same cord) --> trips. Different GFCI breaker (same branch circuit) same extension cord, same lights --> trips. "Cold" lights --> trips. "Warm" lights --> no trip.
Extension + cold lights plugged into non-GFCI branch circuit --> *no* trip. Ditto for different GFCI branch circuit, no trip.
I.e., nothing wrong with extension cord *or* lights.
Toaster oven (reported by SWMBO) plugged into same outlet WITHOUT extension cord --> trips.
Problem is *clearly* with the wiring in the wall -- the only thing common to all fault cases and NOT present in any of the non-fault cases! And, only manifests when a load is present. Furthermore, only when the load is significant ("cold" lamp strings)

The whole point of the discussion is that there *is* a fault! Note that a much larger load (3X) had been present on the same branch circuit last Winter with *no* problems for the entire season!

Forecast was for a cold night, tonight. So, rushed to get *something* working -- regardless of an "explanation" -- in the hour I had before sunset.
As it was obvious that the problem had to be in the branch circuit, I removed all receptacles, examined the routing of the conductors within each Jbox, inspected all wire nuts, screw terminals, grounds, etc. and, then, reassembled everything. Washed the "wet use" covers just to make things look pretty (continuous sun exposure turns the exterior paint to a powdery substance).
No "obvious" problems: no "bugs" falling out of the receptacles, no corrosion on terminals, no exposed wires under wire nut skirts, no nicks in insulation, no moisture in boxes, no mounting screws pressing on conductors, no cables pinched in clamps, plenty of room in each box (35 cu in), etc.
Circuit has been holding without any problem -- even in the (unexpected!) rain that's been falling (and the "false alarm" for the cold weather!). Added another 2 strands of lights (with a second extension cord) just to push my luck...
Took the (inexpensive -- $1) precaution of fitting "child proof" plugs to all unused outlets to ensure nothing *can* crawl into any of the outlets in the future.
No way to ensure I can recreate the problem -- as I have no idea what it *actually* was -- so I'll leave well enough alone and wait for the next hiccup. Maybe buy some 20A receptacles to replace these when I next have to go poking around in the Jboxes...
Case closed.
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On 12/12/2015 3:11 AM, Don Y wrote:

Perhaps something wasn't plugged all the way in and you fixed it when you checked everything?
--
Maggie

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wrote:

More likely that there was a neutral fault that was cleared when he pulled everything apart and put it back. Lots of mystery GFCI problems are fixed by an inspection that didn't actually find a problem. Who knows what it was?
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On Sat, 12 Dec 2015 12:37:50 -0500, snipped-for-privacy@aol.com wrote:

"It's all in the way you hold your mouth"
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On Sat, 12 Dec 2015 13:40:02 -0500, snipped-for-privacy@snyder.on.ca wrote:

A very unrecognized skill in this business ;-)
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