GFCI's

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On Wed, 02 Dec 2015 00:25:12 -0700, Don Y

Make up a "soft start box" getr an electric heater. take a short extension cord (or make one uo) and cut the live wire, inserting a second plug in series with the existing one. Plug the heater into the second plug, the lights into the first. This will reduce the current on startup. Wire a switch across the second plug so you can short the heater out of the circuit after the lights come on. This will tell you for sure if it is a cold surge problem. If you get a 750/1500 heater you can select how hard or soft the start is.
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On 12/2/2015 5:36 AM, snipped-for-privacy@snyder.on.ca wrote:

"plug" --> "outlet"

Given that the load is so light, I can use an electric hair dryer and fiddle with the temp setting (cold/warm/hot/blistering) to gradually increase the effective load. A switch shunting the hair dryer's connection to remove it completely.
It's worth a try. I'm going to gather more data, first, so I know exactly how I can reproduce the problem (e.g., if I have to wait 2 hours for the "short" to redevelop, then any tests more frequent than that would be foolish.
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So there are 3 strings of lights?
Try switching the breaker on with 2 out of 3 strings plugged in, i.e one string unplugged..
THen change to another 2 out of 3 etc i.e another one unplugged.
If it still trips with 2/3 , it's leakage. If it doesn't, it's surge current.
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On 12/2/2015 7:36 AM, snipped-for-privacy@yahoo.com wrote:

There are three strings "in series" (this is a misnomer; they are obviously WIRED in parallel, but, each string plugs into the string "upstream" from it. I.e., the first two strings act as an "extension cord" for the third; the first string acts as an extension for the second and third; etc.

Note my comment that, in years past, we would have up to 10 (effectively) strings on the same *single* outlet. E.g., extension cord would run to the base of the tree. There, a "cube tap" made 3 receptacles available from the ONE that is present on the extension cord. Two strings were plugged into that cube tap. Two *more* strings were plugged into the "ends" of each of these first two strings. And, two more plugged into the ends of each of those.
So, "two strings of three". Each string has 25 (?) 9W (nominal) lamps so ~225W/string or 675W per string-of-3; 1350W for the pair of these.
The third outlet on the cube tap would either feed a (65W?) flood light sited beneath the tree (again, the goal is to cause convective air currents from the *heat* generated by the lamps -- incandescent lamps being notoriously inefficient at generating VISIBLE light).
Another extension cord would run from the other half of the same duplex receptacle off to another tree -- with a set of 3 strings, there.
Or, variations on that theme.
I.e., we would typically be pushing the 20A circuit as far as we could with a "static" load.
As there's no "switch" to turn these on and off, it's easiest to just flip the breaker for that circuit (there's nothing else on it). So, we would turn the breaker on each (late) evening and off each (early) morning -- in much the same way you'd turn lights on and off in a house.
*We* have "changed" nothing. Yet, something *has* changed. We're not seeing extraordinarily cold weather (hovering around 30F, recent nights) whereas we've seen high teens in years past.
It's not raining -- whereas we've had the lights ON in rainy weather, previously (hence the use of the GFCI -- lest we dance the "electric bugaloo" when we step outside!)
The house is masonry construction so doesn't "move" to affect the wiring in any way. Outlets recessed into the block walls so not directly exposed to the elements.
<frown>
It would be silly to add more strings just to prove it can't handle an even BIGGER load...
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[snip]

C9 lights? The 9 is the size of the bulb (I think 9mm across). IIRC power consumption is 7W.
[snip]
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22 days until the winter celebration (Friday December 25, 2015 12:00:00
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On 12/3/2015 3:12 PM, Mark Lloyd wrote:

Dunno. The "9" stuck in my mind. They are the "really big" incandescents (not to be confused with the smaller 4W and 7W (identical to the 4W in size) "night lights" you'd encounter in a house.
[I don't have any spare bulbs in store-bought packages; and the actual strings get stored in shoebox sized boxes (that aren't actually for shoes) cuz it's impractical to try to cram them back into the boxes in which they originally were purchased).]
For other incandescents, often the wattage is stamped in the metal screw base. I should see if I can read anything (that small) there...
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On Tue, 01 Dec 2015 19:19:01 -0700, Don Y

My 1979 house near Baltimore was built with one GFCI circuit that powers the front outdoor receptacle, the recepts in each bathroom, and iirc the one near the sink in the kitchen.
I bought the house when it was 4 years old, and within a couple years, the breaker kept tripping, but the replacement has only tripped twice in 30 years.
For the last 12 years I've had a heavy orange extension cord plugged into the front outdoor outlet, or into an extension cord plugged into it. The female end of both has lain in the grass for the last 12 years, 365 days a year/24, through rain and snow and sleet and gloom of night. And the breaker has only tripped twice. Many different locations, wherever I feel like throwing it at the end of the day.
I do make a point to pick it up a foot from the end when it's wet.

I use a B&D elelctric lawnmower with no problem, but i don't know its rating or other things about your question.

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wrote:

What are yiou using for lights? It sounds like they are incandescent C9 bulbs in strings of 25 bulbs. (which is actually 225Watts). [25 times 9watts].

700W is not even close to 20A. A 20A breaker can handle roughly 2400 watts. (Of course you dont want to run it at it's maximum load). Either way, 700W is only around 30% of the capacity of the breaker. Yea, starting current is always higher, but even if it was double (1400) watts, you're still way below the allowable load limit for a 20A circuit.

Check, check twice, check 3 times and check again for any minor breaks in the light strings. One very tiny spot of bare wire, a bulb base slightly exposed and touching a tree branch, or the soil, and so on.... Christmas light strings are notorious for electrical leakage and if they're old, even more so.
Also, years ago, when I used to decorate outside of my parents house, using those C9 (and C7) strings, more than once one of the bulbs seemed to develop an internal short. Apparently the filament broke, but welded itself back together but it was shorter and drew excess current. That bulb would eventually burn out, but sometimes it would blow a fuse when it died.
So, you might check every bulb for any sign of defect, which is easier said than done. Or replace all the bulbs in one string at a time.
Better yet, just buy some C9 sized LED strings, and if you have them on every night until the end of December, they will probably pay for themselves in electrical savings. Just a guess, but a string of 25 LEDs probably use about 20 to 30 watts.
Three strings of incandescent will use 675W (Roughly 700W) every hour. So whatever you pay per KWH, is spent approximately every 1-1/2 hours.
As an example, if you pay 15 cents per KWH, Six hours per day will cost you 60 cents per night. That's a cost of $18 for one month.
Three LED strings will use around 80W per hour. 480W in 6 hours, which amounts to about 7 cents per day or $2.10 for an entire month.
You save $15.90 in that month.
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On Wed, 02 Dec 2015 03:35:57 -0600, snipped-for-privacy@unlisted.moc wrote:

But the current spike on LEDs can be pretty healthy too- depending what kind of driver circuit. Just a series string, not so much - but LED drivers? OUCH!!
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install a regular switch or a timer after the breaker.
not only more convenient, but long term using a breaker as a switch can lead to breaker failure.
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On 12/2/2015 7:55 AM, bob haller wrote:

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).
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On Wed, 02 Dec 2015 08:07:12 -0700, Don Y

What happens if the breaker is already on and you just plug in the lights?
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On 12/2/2015 8:39 AM, snipped-for-privacy@aol.com wrote:

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.)
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On 12/2/2015 11:02 AM, Don Y wrote:

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.
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Many many years ago I worked as an electrician in a hospital that had an in door pool. Every day when the attendant turned on the Metal Halide HID ove rhead lights over the pool deck, the GFCI circuit breakers would trip. I c hanged the breakers and tighten the connections, but the symptoms never wen t away. When the circuit breakers were reset, the lights stayed on until t he pool closed when they were then intentionally shut off. The next day wo uld bring the same symptoms. I had surmised that perhaps the high humidity environment was causing condensation on the ballasts, but that was just a b est guess. After a while I gave up and just made it my business to turn on the pool lights every day.
John Grabowski http://www.MrElectrician.TV
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On 12/3/2015 5:18 PM, John G wrote:

You haven't explicitly said it (and, as I suspect they are considerably ABOVE the pool, it might not be required?) but were teh HID's the load that the GFCI(s) were protecting? Or, were there other GFCI circuits and the "noise" (?) from the HID's interfering with them?

So, that's the same behavior I'm reporting? I.e., first ("cold") attempt to turn on causes breaker to trip (i.e., before it ever latches!). But, immediately thereafter, a subsequent attempt to turn on works properly?

How soon after the first failure would you reattempt? Would it seem logical that any condensate would/could evaporate in that time? (i.e., not liquid water, perhaps, but "dampness"?)

I will return to a more structure testing "program" this weekend (assuming nothing else rises to the top of the Honey-Do's). Among other things, I'd like to know if, once "holding", the crcuit will actually hold its full rated load. Or, if there is yet another set of symptoms to add to the list...
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