GFCI's

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On 12/2/2015 12:31 PM, dpb wrote:

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. <frown> So, instead of using the daylight hours to troubleshoot the problem, I'll waste them running around buying "stuff". (sigh)
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On 12/02/2015 1:59 PM, Don Y wrote:

...

...

I just had basically agreed with that assessment...as said, hadn't seen that diagnostic result previously.
...

Precisely; since you later say you have other extension cords I suggest swapping it out on the same breaker next before doing anything more involved.

...
Any of that starts to seem pretty far-fetched to me albeit almost anything is possible. OH, just a really far-out thought--you don't have any of the "crazy ants" there, do you? They can cause all kinds of really bizzaro thingos/symptoms if they've found a receptacle box and set up shop...
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On 12/2/2015 2:58 PM, dpb wrote:

It could still be a problem with the strings of lights; they have all seen roughly the same sort of use, over the years. Something that happens to one lamp in one string could also have happened to another lamp in another string, etc. With 25 lamps in each string -- plus a plug on one end and an outlet on the other, that's ~80 places a problem could infest!

Too late to do anything more, today. I'll just turn the lights on and deal with it, again, tomorrow (if I have spare time).

We have "leaf cutter wasps (bees?)" that fill little holes with rolled up pieces of leaves that they use to make their nests.
Other wasps (?) look for little holes to fill with *mud* nests.
And, of course, various little spiders, etc.
It seems like the size of the safety ground hole in an outlet is what they target. E.g., I have found that if I leave 1/4" irrigation tuning on the table in the back porch, when I later go to use it, one (or both!) ends will be neatly plugged with mud.
That's why I think removing the receptacles (starting with those that aren't currently powering loads) is a quick first step. Easier than messing around in the panel (I can turn off the breaker and work on the receptacles without fear of catching a jolt).
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On Wed, 02 Dec 2015 12:59:43 -0700, Don Y

Get a spare non-gfi breaker. Pop it into the panel in place of the GFCI and see what happens.
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On 12/2/2015 7:48 PM, snipped-for-privacy@snyder.on.ca wrote:

Have to open the "main" side in order to run the neutral leg for that branch circuit over to the "neutrals" tie point.
Nothing is ever "easy"...
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On Wed, 02 Dec 2015 19:56:00 -0700, Don Y

On my QO panel it's easy - neutral buss on both sides. Putting in the GFCI I had to extend the neutral because the sparky that replaced the panel didn't run the neutrals for the breakers on the one side to the same side as the breaker - he put all the neutrals on the "short" side. VERY neet job - but made it difficult to install GFCI breakers in the panel.
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On 12/3/2015 2:33 PM, snipped-for-privacy@snyder.on.ca wrote:

In our case, the ground/neutral bus is located on the meter side of the panel. I.e., to gain access, you have to expose the AC mains on the output of the meter connection/input to main disconnect/output of main disconnect.
Of course, the bus bar is mounted against the rear of the panel, so you have to reach *into* the panel (with screwdriver) to open the lockdown screws in the bar. Then, reach in with your *fingers* to thread the neutral wire (or, neutral pigtail!) under the lockdown screw -- before tightening it.
So, all of the GFCI's must be located at the top of the loadcenter side of the panel -- else their pigtails won't reach the grounding bar! And, all the neutrals have to work their way up to the top of the box where they can cross over to the meter side to tie into the ground *and* neutral!
I.e., I don't like opening that side of the box! :>
You can replace a breaker just by prying the "tongue" side loose. Then, with the breaker IN YOUR HAND, you can leisurely remove the hot conductor from it! (and neutral, if a GFCI). You don't have to make any penetration into the box (and the bus bars waiting there!)
OTOH, if you opt to replace a GFCI with a non-GFCI, you now have to figure out how to get the branch circuit's neutral over to the meter side of the box!
(and, if you're only doing this to test a theory, you look for other ways to garner that information that are less involved! :> )
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On Wednesday, December 2, 2015 at 2:07:56 PM UTC-5, Don Y wrote:

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
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On 12/2/2015 12:57 PM, snipped-for-privacy@yahoo.com wrote:

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...
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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
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On 12/2/2015 1:31 PM, snipped-for-privacy@yahoo.com wrote:

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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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!
You do know that incandescent bulbs can pull about 10x the current on turn on?
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On 12/2/2015 5:53 PM, snipped-for-privacy@yahoo.com wrote:

Yes. And you'll note that when we were pulling 2000W in previous years, THE BREAKER NEVER TRIPPED!
(We've been growing oranges for 15+ years)
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On Wednesday, December 2, 2015 at 7:54:08 PM UTC-5, snipped-for-privacy@yahoo.com wrote:

You do know that having 700W of incandescents on even a 15A circuit is very common and doesn't cause breakers tripping?
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OK...Lets talk details.
I don't know the details of the inards of GFI breakers. Maybe you do.
Lets say the COLD turn on surge is 20 Amps for a short time and that alone is not enough to trip a 20 A breaker.
Lets say there is also 3 mA of leakage and the trip point for the GFI break er is 5 mA so 3 mA alone is not enough to trip the breaker.
But what about both together? Maybe both together will trip.
I don't know if each trip point is totally seperate inside the breaker or if they somehow are added. Do you? (I'm not trying to be snooty)
I do know that a truely COLD bulb turn on draws a bigger surge then one whe re the bulbs have been pre warmed. It doesn't seem logical I agree, but I have seen it. You have to wait a good number of seconds for the filament to totally cool to get the full surge current.
It doesn't seem like this small diffence should be the OPs problem but at this point, who knows?
I agree with the suggestion to change to a non GFI breaker as a test to el iminate the leakage part of the question.
Mark
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On Thursday, December 3, 2015 at 9:04:11 AM UTC-5, snipped-for-privacy@yahoo.com wrote:

e is not enough to trip a 20 A breaker.

aker is 5 mA so 3 mA alone is not enough to trip the breaker.

r if they somehow are added. Do you? (I'm not trying to be snooty)

Yes, they are separate. The fault current is measured by comparing the balance between the current in the hot and neutral and it trips independently of the overall current. Adding wouldn't get you anywhere because the fault current trip is three orders of magnitude smaller than the load current trip.

here the bulbs have been pre warmed. It doesn't seem logical I agree, but I have seen it. You have to wait a good number of seconds for the filamen t to totally cool to get the full surge current.

I agree that cold bulbs will draw a lot more current initially.

at this point, who knows?

eliminate the leakage part of the question.

I thought he said he had done that and it worked without tripping?
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On Thursday, December 3, 2015 at 9:17:11 AM UTC-5, trader_4 wrote:
e:

one is not enough to trip a 20 A breaker.

reaker is 5 mA so 3 mA alone is not enough to trip the breaker.

or if they somehow are added. Do you? (I'm not trying to be snooty)

Of course the currents are not added directly. That is not what i meant. 5 mA is nothing compared to 20A.
I mean the trip forces in the mechanism might add.
If 19 Amps puts say 1 pound of force on the trip mechanism and 3 mA also p uts one pound of force, then each alone might not trip it, but together the y put 2 pounds of force which could be enough to trip it.
These are mechanical devices afterall.
Mark

where the bulbs have been pre warmed. It doesn't seem logical I agree, b ut I have seen it. You have to wait a good number of seconds for the filam ent to totally cool to get the full surge current.

at this point, who knows?

o eliminate the leakage part of the question.

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On Thursday, December 3, 2015 at 12:01:30 PM UTC-5, snipped-for-privacy@yahoo.com wrote:

The GFCI isn't putting gradual force on the breaker to open it. It's detecting when a fault current exceeds the ~6ma level and driving a solenoid that opens the breaker. It's an all or nothing, instantaneous, thing, not gradual.
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On Thu, 3 Dec 2015 09:01:23 -0800 (PST), snipped-for-privacy@yahoo.com wrote:

On the Square D the 2 trip mechanisms are totally separate, and the GFCI load section is the same as the non GFCI breaker. No idea what breakers you have in the CH panel, but "generally" that is how they are made.
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On 12/3/2015 7:03 AM, snipped-for-privacy@yahoo.com wrote:

We know it isn't -- because I moved the extension cord to a non-GFCI circuit and the circuit had no problem holding the load.
(We also know that in years past, a 15A-18A load had no problem on the same GFCI circuit!)

I don't know. Clearly (?) there is something "GFCI-related" with the current situation -- as a second GFCI breaker swapped in to replace the original GFCI breaker is behaving exactly the same way.

I don't. As I pointed out upthread, there's no guarantee that a non-GFCI's current holding characteristics, response time, etc. are the same as that of a GFCI breaker WITH THE GFCI PORTION DISABLED.

Again, note the (apparently thermal) characteristics reported: - breaker IMMEDIATELY trips when switched on with a "cold" load (we'll leave the definition of "cold" vague, for now) - seconds later, throwing the breaker holds, indefinitely - "cold" lamps "plugged into" a live circuit immediately trip it - lamps that have been on for hours can be unplugged and replugged within 1 (or 10!) seconds and the circuit will hold - lamps that have been allowed to "rest" for 2 minutes will immediately trip the breaker
It sure *seems* like allowing things to "cool off" -- or, starting with something "cold" -- is the differentiating aspect of the problem.

Note that all this would do is isolate the "in wall wiring" as a potential cause of an hypothesized GFCI issue. We've already tried a non-GFCI branch circuit with the extension cord and lamps.
I'll try plugging the extension cord into a kitchen outlet (unloaded circuit) as that would test a different GFCI with the existing extension cord BUT DIFFERENT WIRING (as we've already tried a different GFCI with the existing extension cord and THE SAME WIRING).
[This is easy to do whereas tying the existing wiring to a nonGFCI breaker is a significant effort]
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