On 12/2/2015 1:15 PM, wrote:
On Wed, 02 Dec 2015 11:08:06 -0700, Don Y
wrote:

On 12/2/2015 10:56 AM, Don Y wrote:
On 12/2/2015 8:31 AM, wrote:
On Wed, 02 Dec 2015 00:13:36 -0700, Don Y
wrote:

On 12/1/2015 8:00 PM, wrote:
On Tue, 01 Dec 2015 21:46:03 -0500, wrote:

On Tue, 01 Dec 2015 19:26:18 -0700, Don Y
wrote:

On 12/1/2015 7:19 PM, Don Y wrote:
The outlets in the back of the house are on a 20A GFCI.

For those who didn't connect the dots, this is a GFCI *breaker*,
not a GFCI *outlet* daisy-chained to feed the others.
Does it trip with nothing connected? If not, it's not a dauber or
anything on the main circuit. It has to be on the "load". Outdoor
lights on a GFCI can be a problem - lots of possibilities for
"leakage"

If there is absolutely nothing connected, a neutral fault will not
trip the GFCI. The slightest load will trip it tho. (it splits the
neutral current)
The other thing to remember is the faults are additive. If you are
leaking a couple ma in a couple places, it will work until the total
gets up around 5ma or so.

You're ignoring the fact that the breaker latches and HOLDS on the
"second attempt". This suggests the problem is related to the
change in load characteristics from the previous "brief lighting
event" (fraction of a second when power surged into the lamps
just before the breaker trips on the first attempt).

I'm at a loss to explain how anything else could appear and
then disappear so readily!

If it is a clump of moist material, you may be cooking the moisture
out a little with the first attempt.

Then, what is "rehydrating" the material for the *next* time it
trips? No rain, here. Low humidity. No plumbing anywhere
nearby.

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.

You may just have a bad breaker.

Did you miss the point where I said I replaced the breaker?
TWO bad breakers? But the other three located within inches
in the panel are all OK? Swap one of those in for the
bad circuit (wanna bet that would be a wasted effort??)

On 12/02/2015 1:59 PM, Don Y wrote:
On 12/2/2015 12:31 PM, dpb wrote:
On 12/02/2015 1:08 PM, Don Y wrote:
On 12/2/2015 11:54 AM, dpb wrote:
....
....

....

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.

....

The fact that the different strings don't appear to make any
difference to the result *suggests* it's not in the "load".

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

....

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).

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.

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.
....

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...

--

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?

On 12/2/2015 5:53 PM, wrote:
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?

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)

On Wed, 02 Dec 2015 13:45:31 -0700, Don Y
wrote:

On 12/2/2015 1:15 PM, wrote:
On Wed, 02 Dec 2015 11:08:06 -0700, Don Y
wrote:

On 12/2/2015 10:56 AM, Don Y wrote:
On 12/2/2015 8:31 AM, wrote:
On Wed, 02 Dec 2015 00:13:36 -0700, Don Y
wrote:

On 12/1/2015 8:00 PM, wrote:
On Tue, 01 Dec 2015 21:46:03 -0500, wrote:

On Tue, 01 Dec 2015 19:26:18 -0700, Don Y
wrote:

On 12/1/2015 7:19 PM, Don Y wrote:
The outlets in the back of the house are on a 20A GFCI.

For those who didn't connect the dots, this is a GFCI *breaker*,
not a GFCI *outlet* daisy-chained to feed the others.
Does it trip with nothing connected? If not, it's not a dauber or
anything on the main circuit. It has to be on the "load". Outdoor
lights on a GFCI can be a problem - lots of possibilities for
"leakage"

If there is absolutely nothing connected, a neutral fault will not
trip the GFCI. The slightest load will trip it tho. (it splits the
neutral current)
The other thing to remember is the faults are additive. If you are
leaking a couple ma in a couple places, it will work until the total
gets up around 5ma or so.

You're ignoring the fact that the breaker latches and HOLDS on the
"second attempt". This suggests the problem is related to the
change in load characteristics from the previous "brief lighting
event" (fraction of a second when power surged into the lamps
just before the breaker trips on the first attempt).

I'm at a loss to explain how anything else could appear and
then disappear so readily!

If it is a clump of moist material, you may be cooking the moisture
out a little with the first attempt.

Then, what is "rehydrating" the material for the *next* time it
trips? No rain, here. Low humidity. No plumbing anywhere
nearby.

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.

You may just have a bad breaker.

Did you miss the point where I said I replaced the breaker?
TWO bad breakers? But the other three located within inches
in the panel are all OK? Swap one of those in for the
bad circuit (wanna bet that would be a wasted effort??)

How much cord do you have out there and is it still on that spool?

I would keep eliminating the various components in this circuit until
you get to what the problem is.

On 12/2/2015 2:58 PM, dpb wrote:

The fact that the different strings don't appear to make any
difference to the result *suggests* it's not in the "load".

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

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!

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).

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.

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).

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.
....

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...

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).

On 12/2/2015 6:36 PM, wrote:

You may just have a bad breaker.

Did you miss the point where I said I replaced the breaker?
TWO bad breakers? But the other three located within inches
in the panel are all OK? Swap one of those in for the
bad circuit (wanna bet that would be a wasted effort??)

How much cord do you have out there and is it still on that spool?

The same amount that has been out there and on the spool for the
last ~decade. I can swap to another spool. I can unwind it all.
But, none of those seem like reliable alternatives (do I then
start considering trimming the length of the cord, etc.?)

I would keep eliminating the various components in this circuit until
you get to what the problem is.

Well, that's sort of obvious! : The trick is figuring it out
before trying the last possible option!

On Wed, 02 Dec 2015 10:56:19 -0700, Don Y
wrote:

On 12/2/2015 8:31 AM, wrote:
On Wed, 02 Dec 2015 00:13:36 -0700, Don Y
wrote:

On 12/1/2015 8:00 PM, wrote:
On Tue, 01 Dec 2015 21:46:03 -0500, wrote:

On Tue, 01 Dec 2015 19:26:18 -0700, Don Y
wrote:

On 12/1/2015 7:19 PM, Don Y wrote:
The outlets in the back of the house are on a 20A GFCI.

For those who didn't connect the dots, this is a GFCI *breaker*,
not a GFCI *outlet* daisy-chained to feed the others.
Does it trip with nothing connected? If not, it's not a dauber or
anything on the main circuit. It has to be on the "load". Outdoor
lights on a GFCI can be a problem - lots of possibilities for
"leakage"

If there is absolutely nothing connected, a neutral fault will not
trip the GFCI. The slightest load will trip it tho. (it splits the
neutral current)
The other thing to remember is the faults are additive. If you are
leaking a couple ma in a couple places, it will work until the total
gets up around 5ma or so.

You're ignoring the fact that the breaker latches and HOLDS on the
"second attempt". This suggests the problem is related to the
change in load characteristics from the previous "brief lighting
event" (fraction of a second when power surged into the lamps
just before the breaker trips on the first attempt).

I'm at a loss to explain how anything else could appear and
then disappear so readily!

If it is a clump of moist material, you may be cooking the moisture
out a little with the first attempt.

Then, what is "rehydrating" the material for the *next* time it
trips? No rain, here. Low humidity. No plumbing anywhere
nearby.

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

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!
What brand panel and breaker?

On Wed, 02 Dec 2015 11:53:14 -0700, Don Y
wrote:

On 12/2/2015 11:08 AM, Don Y wrote:
On 12/2/2015 10:56 AM, Don Y wrote:
On 12/2/2015 8:31 AM, wrote:
On Wed, 02 Dec 2015 00:13:36 -0700, Don Y
wrote:

On 12/1/2015 8:00 PM, wrote:
On Tue, 01 Dec 2015 21:46:03 -0500, wrote:

On Tue, 01 Dec 2015 19:26:18 -0700, Don Y
wrote:

On 12/1/2015 7:19 PM, Don Y wrote:
The outlets in the back of the house are on a 20A GFCI.

For those who didn't connect the dots, this is a GFCI *breaker*,
not a GFCI *outlet* daisy-chained to feed the others.
Does it trip with nothing connected? If not, it's not a dauber or
anything on the main circuit. It has to be on the "load". Outdoor
lights on a GFCI can be a problem - lots of possibilities for
"leakage"

If there is absolutely nothing connected, a neutral fault will not
trip the GFCI. The slightest load will trip it tho. (it splits the
neutral current)
The other thing to remember is the faults are additive. If you are
leaking a couple ma in a couple places, it will work until the total
gets up around 5ma or so.

You're ignoring the fact that the breaker latches and HOLDS on the
"second attempt". This suggests the problem is related to the
change in load characteristics from the previous "brief lighting
event" (fraction of a second when power surged into the lamps
just before the breaker trips on the first attempt).

I'm at a loss to explain how anything else could appear and
then disappear so readily!

If it is a clump of moist material, you may be cooking the moisture
out a little with the first attempt.

Then, what is "rehydrating" the material for the *next* time it
trips? No rain, here. Low humidity. No plumbing anywhere
nearby.

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 :
Not aluminum, by chance??

On Wed, 02 Dec 2015 12:59:43 -0700, Don Y
wrote:

On 12/2/2015 12:31 PM, dpb wrote:
On 12/02/2015 1:08 PM, Don Y wrote:
On 12/2/2015 11:54 AM, dpb 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.

....

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?

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)
Get a spare non-gfi breaker. Pop it into the panel in place of the
GFCI and see what happens.

On Wed, 02 Dec 2015 13:43:52 -0700, Don Y
wrote:

On 12/2/2015 1:31 PM, wrote:


In the past, there were 3 times as many bulbs in place without a problem!


wow

so maybe your breakers aged... (I'm serious, they do age)

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)

or you changed extension cords to a heavier guage?

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.

or there is other load in another outlet on the same breaker

Nope. Only 5 (duplex) outlets. Four of them along the back
of the house, the fifth around the side.

I would as a test change to a non GFI breaker to eliminate that possibility.

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]

I didn't see the naswer to the 2 out of 3 question, what if you use 2 strings instead of 3?

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!

I think you can pretty definitevly rule out tripping from the load of
the lights - cold surge or not.
How old are the light strings? Or the extension cords?

My strong suspicion is you have electrical leagage somewhere - the
lights are shorting to ground (very high resistance), the cord is
leaking to ground (very high resistance) or you have a leakage
somewhere in the house wiring/outlets.

On 12/2/2015 7:48 PM, wrote:

Get a spare non-gfi breaker. Pop it into the panel in place of the
GFCI and see what happens.

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"...

On 12/2/2015 7:45 PM, wrote:
Beyond that, I'll have to start opening wire nuts -- not something
I like doing with #12AWG :
Not aluminum, by chance??

God, no!

On 12/2/2015 7:35 PM, wrote:

What brand panel and breaker?

Old CH.

On 12/2/2015 7:54 PM, wrote:

I think you can pretty definitevly rule out tripping from the load of
the lights - cold surge or not.
How old are the light strings? Or the extension cords?

The strings are varying ages. It's not like we made note of when
we got each set. Cords are probably 10 years old. They stay
indoors except for this time of year.

My strong suspicion is you have electrical leagage somewhere - the
lights are shorting to ground (very high resistance),

Lights can't short to "ground" cuz they're only two wire devices
(tree isn't a very good conductor when you consider the wires
tend to lay on leaves)

the cord is
leaking to ground (very high resistance)

Possible as its a 3 conductor extension.

or you have a leakage
somewhere in the house wiring/outlets.

Also possible. However, I don't consider any of those to be
LIKELY!

I.e., why would it "leak" then NOT leak a second later
(when power applied from the breaker).

And, when *hot*, not leak for 8 hours of continuous use;
not leak after being disconnected for 1 second; not leak
after being disconnected for 10 seconds; then "leak"
when disconnected for 2 minutes??

I.e., what -- other than the temperature/resistance of the
tungsten filaments -- is going to exhibit changes on the
order of "many seconds" (something greater than 10 and less
than 120)?

I wish I still had my Hi-Pot tester! :

On Wednesday, December 2, 2015 at 3:31:45 PM UTC-5, wrote:

In the past, there were 3 times as many bulbs in place without a problem!


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

breakers are designed to get more sensitive as they age. to prevent fires..

I spent at least 15 years repairing machines in the westinghouse vanport in beaver pa breaker plant. aa truly fascinatining place

[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]

thats what main breakers are designed for, changing breakers in a hot panel is just plain dumb...

of course you have to reset clocks etc......

but you have to do that if your home has a power failure

On 12/2/2015 9:05 PM, bob haller wrote:

[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]

thats what main breakers are designed for, changing breakers in a hot panel
is just plain dumb...

Every panel I've ever been in makes it relatively easy to change
a breaker with power on. The breakers typically clip into/onto
one bus bar or the other (or both) so the "live" circuit is
not anywhere near where you are working. Only a section of the
bus bar(s) that you will be connecting to is exposed BETWEEN
the other installed breakers. In our case, that means a slot
5/8" wide and 2+ inches deep to touch the bus bar.

The hot wire running off to the branch circuit can be connected
*before* installing a breaker or disconnected *after* the breaker
is pulled out.

By contrast, the GFCI's require a connection to the neutral
bus. In our panel, that means exposing the AC line *at* the
main breaker. Turning off the breaker gives you very little
added protection -- slip and you're toast.

of course you have to reset clocks etc......

Generational differences? : Sure, we'd have to reset a couple
of bedroom clocks, HiFi's, oven, microwave, etc. And, coordinate
our activities so we're not without power when we're expecting to
do something (make dinner, watch a movie, etc.)

But, that's pretty easy.

The real effort comes with the computers that are undoubtedly
running at the time of the "planned outage".

I'd have to make notes as to what I was doing on each of the
computers that were powered up, at the time (assuming they
aren't actively "doing something" that will take a fair amount
of time -- like rendering a 3D model, "make world", etc.);
examine each open application so I can return to that state
when power is eventually restored.

(I typically leave a machine exactly where it was when I was
last using it so the display reminds me as to what I was doing)

Also, shut down any network appliances or headless servers
in an orderly manner. etc.

Or, hope the batteries in each UPS are stiff enough to
carry the loads for the time you *expect* to need to swap
out the breaker.

I.e., I have to do a fair bit of planning if I want to remove
power for anything more than a few seconds (which I expect
the UPS's to always handle even when batteries are toast).

but you have to do that if your home has a power failure

I have no control over a power failure. I *do* have control
over when -- and IF -- I remove power to do electrical
maintenance!

On Wed, 02 Dec 2015 20:04:37 -0700, Don Y
wrote:


I.e., why would it "leak" then NOT leak a second later
(when power applied from the breaker).

And, when *hot*, not leak for 8 hours of continuous use;
not leak after being disconnected for 1 second; not leak
after being disconnected for 10 seconds; then "leak"
when disconnected for 2 minutes??

Let's say you have a leakage of 4 mA and the GFCI is designed to trip
at a leakage of 3 to 5 mA. At 4 mA, it may or may not trip. For
whatever reason, when first turned on, its trip point is 3 mA (within
spec) but it then rises to nearer 5 mA (still within spec). Wouldn't
that explain what you are seeing? I made up those numbers, but you
get the idea. Look for a small leakage of current from hot to ground
(or a low resistance connection from neutral to ground) that is on the
hairy edge of tripping the GFCI. As others have said, water or bugs
in one of the boxes on the line is the most likely. A neutral to
ground short in one of the boxes is also possible. Good luck. These
things are not easy to find.

Pat

On Wednesday, December 2, 2015 at 7:54:08 PM UTC-5, wrote:
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?

You do know that having 700W of incandescents on even a 15A
circuit is very common and doesn't cause breakers tripping?

You do know that incandescent bulbs can pull about
10x the current on turn on?

You do know that having 700W of incandescents on even a 15A
circuit is very common and doesn't cause breakers tripping?

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 breaker 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 where 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 eliminate the leakage part of the question.

Mark

On Thursday, December 3, 2015 at 9:04:11 AM UTC-5, wrote:

You do know that incandescent bulbs can pull about
10x the current on turn on?

You do know that having 700W of incandescents on even a 15A
circuit is very common and doesn't cause breakers tripping?

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 breaker 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)


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.




I do know that a truely COLD bulb turn on draws a bigger surge then one where 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.


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


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 eliminate the leakage part of the question.

Mark

I thought he said he had done that and it worked without tripping?

On 12/3/2015 7:03 AM, wrote:

You do know that incandescent bulbs can pull about 10x the current on
turn on?

You do know that having 700W of incandescents on even a 15A circuit is
very common and doesn't cause breakers tripping?

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.

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!)

Lets say there is also 3 mA of leakage and the trip point for the GFI
breaker 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. 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 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 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.

I do know that a truely COLD bulb turn on draws a bigger surge then one
where 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.

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.

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
eliminate the leakage part of the question.

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]

On 12/3/2015 4:25 AM, Pat wrote:
On Wed, 02 Dec 2015 20:04:37 -0700, Don Y
wrote:


I.e., why would it "leak" then NOT leak a second later
(when power applied from the breaker).

And, when *hot*, not leak for 8 hours of continuous use;
not leak after being disconnected for 1 second; not leak
after being disconnected for 10 seconds; then "leak"
when disconnected for 2 minutes??

Let's say you have a leakage of 4 mA and the GFCI is designed to trip
at a leakage of 3 to 5 mA. At 4 mA, it may or may not trip. For
whatever reason, when first turned on, its trip point is 3 mA (within
spec) but it then rises to nearer 5 mA (still within spec). Wouldn't

Wait, what is "it" in each of your statements? The actual leakage
current? Or, the *setpoint* -- the point DEFINED BY THE BREAKER -- at
which the GFCI will open the circuit?

What causes it (whatever "it" may be) to rise?

that explain what you are seeing? I made up those numbers, but you
get the idea. Look for a small leakage of current from hot to ground
(or a low resistance connection from neutral to ground) that is on the
hairy edge of tripping the GFCI. As others have said, water or bugs
in one of the boxes on the line is the most likely. A neutral to
ground short in one of the boxes is also possible. Good luck. These
things are not easy to find.

Ha! That last nominated for Understatement of the Year! ;-)

On Thursday, December 3, 2015 at 9:17:11 AM UTC-5, trader_4 wrote:
On Thursday, December 3, 2015 at 9:04:11 AM UTC-5, wrote:

You do know that incandescent bulbs can pull about
10x the current on turn on?

You do know that having 700W of incandescents on even a 15A
circuit is very common and doesn't cause breakers tripping?

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 breaker 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)


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.


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 puts one pound of force, then each alone might not trip it, but together they put 2 pounds of force which could be enough to trip it.

These are mechanical devices afterall.

Mark




I do know that a truely COLD bulb turn on draws a bigger surge then one where 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.


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


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 eliminate the leakage part of the question.

Mark

I thought he said he had done that and it worked without tripping?

On Thursday, December 3, 2015 at 12:01:30 PM UTC-5, wrote:
On Thursday, December 3, 2015 at 9:17:11 AM UTC-5, trader_4 wrote:
On Thursday, December 3, 2015 at 9:04:11 AM UTC-5, wrote:

You do know that incandescent bulbs can pull about
10x the current on turn on?

You do know that having 700W of incandescents on even a 15A
circuit is very common and doesn't cause breakers tripping?

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 breaker 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)


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.


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 puts one pound of force, then each alone might not trip it, but together they put 2 pounds of force which could be enough to trip it.

These are mechanical devices afterall.

Mark


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.

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

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

....

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).

I repeat--

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

[This is easy to do whereas tying the existing wiring to a nonGFCI
breaker is a significant effort]

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

--

On 12/3/2015 11:32 AM, dpb wrote:
On 12/03/2015 10:45 AM, Don Y 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.

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

Different extension cord makes no change in symptoms.

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).

I repeat--

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

(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.

[This is easy to do whereas tying the existing wiring to a nonGFCI
breaker is a significant effort]

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

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 ****y 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)

I repeat--

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

(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:


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

On 12/03/2015 1:21 PM, Don Y wrote:
....

Sorry, I don't mean to sound ****y 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)

One quick one is the possibility of the extension cord having a fault
(particularly as noted, if it's one of the pretty-common type with the
indicator light in the plug). It's a common element in all the
combinations done to date and is simple as compared to many of the other
things you've tried already or proposing to eliminate.

"Willy-nilly" is pretty much what you've done to date; the above is, as
noted, one common element in all. It may _not_ have any bearing but
then again, if it just turned out to be so, then all the other
pontificating is of little value.

(PS) And, no, on the GFCI circuit breaker I'm not specifically aware --
don't have any and plan to live out my life that way. If it's not
feasible, then ok, so be it.

--

On 12/3/2015 12:36 PM, wrote:


I repeat--

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

(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:

sorry but that is a part of troubleshooting Swapping around parts that you
already have can be a very efficeint troubleshooting technique.

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"?)

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.

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

Sounds like we have nothing more to offer you in the way of help.

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

Be sure to come back and let us know what the answer turns out to be.

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.

On 12/3/2015 12:44 PM, dpb wrote:
On 12/03/2015 1:21 PM, Don Y wrote:
....

Sorry, I don't mean to sound ****y 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)

One quick one is the possibility of the extension cord having a fault
(particularly as noted, if it's one of the pretty-common type with the
indicator light in the plug). It's a common element in all the combinations
done to date and is simple as compared to many of the other things you've tried
already or proposing to eliminate.

But, it has to be a "leak" -- as the problem doesn't manifest when
plugged into a non-GFCI circuit.

And, that "leak" has to somehow be healing itself, then reappearing
(based on whether or not the lights have been on or off and for how
long!)

"Willy-nilly" is pretty much what you've done to date; the above is, as noted,
one common element in all. It may _not_ have any bearing but then again, if it
just turned out to be so, then all the other pontificating is of little value.

I've been "willy nilly" in an attempt to be polite to folks offering
suggestions here. It's not how *I* would have tackled the problem.
But, having asked, it would be rude to dismiss suggestions when
(in MOST cases -- change breaker, change load, plug into different
outlet, swap extension cord, etc.) I can just do the test to humor
the respondent.

But, the "try this" can go on indefinitely. And, you can always
rationalize a semi-legitimate justification for each such attempt!
(e.g., ALL of the lamps have been out in the elements; perhaps
they've *all* been affected in some way! So, it doesn't matter
which strings you try, the problem will persist -- cuz it's
in ALL of them!)

[I worked on a piece of test equipment many years ago. There was
a short between two of the power supplies -- on a "circuit board"
that was 2 ft wide, 6 feet long and contained *thousands* of
components! I.e., the short could be in any of those components.
Or, in the board, itself. Troubleshooting all those potential
connections -- considering that the short was an UNINTENDED
connection -- would be a daunting task. Better to replace the
board and start over... after several months of delay!

I hypothesized that a capacitor could be the "short" -- they were
all over the (brand new!) board. Of course, *which* capacitor
was the problem!

So, I simply picked one AT RANDOM, removed it from the circuit
and tested it.

Shorted!

My colleagues looked at me like I had just walked on water:
not only had I come up with the "problem" but also managed to
find the defective capacitor, on my first attempt!

Boss, quickly turned that optimism into an accusation: "There's
no way you could have known that THAT capacitor was the failed
device! You *put* that there!!"

frown Sort of unfair -- given that I'd just saved his *ss!

I came back later to be greeted by news that *all* of the capacitors
were shorted! (WTF??) Turned out, the board manufacturer had
installed capacitors with the wrong voltage rating and, as soon as
we had applied power, they all went "pffft!"

So, there was no "luck" involved in my finding THE shorted capacitor.
OTOH, there was *genius* in my REASONING that it could be *a*
shorted capacitor -- and not a wire that was misplaced (of the
tens of thousands on the board)!]

(PS) And, no, on the GFCI circuit breaker I'm not specifically aware -- don't
have any and plan to live out my life that way. If it's not feasible, then
ok, so be it.

My problem *has* to be related to the GFCI characteristics of the "circuit".
And, not the GFCI detection itself (faulty breaker) but, rather, some
aspect of what it is testing that the current configuration happens
to "tickle" -- and, only in those cases where it *does* tickle (also
accounting for those cases where it *doesn't*!)

On 12/03/2015 3:08 PM, Don Y wrote:
....

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"?)

A thermal effect as postulated previously.

....

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

....

_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...

--

On Wed, 02 Dec 2015 19:56:00 -0700, Don Y
wrote:

On 12/2/2015 7:48 PM, wrote:

Get a spare non-gfi breaker. Pop it into the panel in place of the
GFCI and see what happens.

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"...
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.

On Wed, 02 Dec 2015 19:56:17 -0700, Don Y
wrote:

On 12/2/2015 7:45 PM, wrote:
Beyond that, I'll have to start opening wire nuts -- not something
I like doing with #12AWG :
Not aluminum, by chance??

God, no!

Just wondered with 12G - so they are 20 amp circuits - - -

On Wed, 02 Dec 2015 19:56:58 -0700, Don Y
wrote:

On 12/2/2015 7:35 PM, wrote:

What brand panel and breaker?

Old CH.
Bolt on or snap on? I've seen a lot of issues lately on the old CH
panels - (I'm talking from the '70s) - failing breakers and no direct
replacements - so guys put in the new ones and butcher the panel cover
to make them fit.

On 12/3/2015 2:26 PM, dpb wrote:
On 12/03/2015 3:08 PM, Don Y wrote:
....

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"?)

A thermal effect as postulated previously.

....

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

....

_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...

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!

On Wed, 02 Dec 2015 20:04:37 -0700, Don Y
wrote:

On 12/2/2015 7:54 PM, wrote:

I think you can pretty definitevly rule out tripping from the load of
the lights - cold surge or not.
How old are the light strings? Or the extension cords?

The strings are varying ages. It's not like we made note of when
we got each set. Cords are probably 10 years old. They stay
indoors except for this time of year.

My strong suspicion is you have electrical leagage somewhere - the
lights are shorting to ground (very high resistance),

Lights can't short to "ground" cuz they're only two wire devices
(tree isn't a very good conductor when you consider the wires
tend to lay on leaves)

Leakge from deteriorated insulation to the leaves is all it takes to
trip a GFCI - and the fact they "stick" on the second or third attempt
means they could be just drying themselves out enough to reduce the
leak enough to not trip the third time.

a 5ma leak is low enough you generally will not even feel it if you
are holding the wire and causing the "leak"
the cord is
leaking to ground (very high resistance)

Possible as its a 3 conductor extension.

or you have a leakage
somewhere in the house wiring/outlets.

Also possible. However, I don't consider any of those to be
LIKELY!

I.e., why would it "leak" then NOT leak a second later
(when power applied from the breaker).

And, when *hot*, not leak for 8 hours of continuous use;
not leak after being disconnected for 1 second; not leak
after being disconnected for 10 seconds; then "leak"
when disconnected for 2 minutes??

I.e., what -- other than the temperature/resistance of the
tungsten filaments -- is going to exhibit changes on the
order of "many seconds" (something greater than 10 and less
than 120)?

I wish I still had my Hi-Pot tester! :

On Wed, 2 Dec 2015 20:05:12 -0800 (PST), bob haller
wrote:


[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]

thats what main breakers are designed for, changing breakers in a hot panel is just plain dumb...

of course you have to reset clocks etc......

but you have to do that if your home has a power failure
On a square D QO panel you'd have to be pretty stupid to shock
yourself changing a breaker with the panel "live". Like you'd almost
have to TRY.

On Wed, 02 Dec 2015 23:02:47 -0700, Don Y
wrote:

On 12/2/2015 9:05 PM, bob haller wrote:

[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]

thats what main breakers are designed for, changing breakers in a hot panel
is just plain dumb...

Every panel I've ever been in makes it relatively easy to change
a breaker with power on. The breakers typically clip into/onto
one bus bar or the other (or both) so the "live" circuit is
not anywhere near where you are working. Only a section of the
bus bar(s) that you will be connecting to is exposed BETWEEN
the other installed breakers. In our case, that means a slot
5/8" wide and 2+ inches deep to touch the bus bar.

The hot wire running off to the branch circuit can be connected
*before* installing a breaker or disconnected *after* the breaker
is pulled out.

By contrast, the GFCI's require a connection to the neutral
bus. In our panel, that means exposing the AC line *at* the
main breaker. Turning off the breaker gives you very little
added protection -- slip and you're toast.

of course you have to reset clocks etc......

Generational differences? : Sure, we'd have to reset a couple
of bedroom clocks, HiFi's, oven, microwave, etc. And, coordinate
our activities so we're not without power when we're expecting to
do something (make dinner, watch a movie, etc.)

But, that's pretty easy.

The real effort comes with the computers that are undoubtedly
running at the time of the "planned outage".

I'd have to make notes as to what I was doing on each of the
computers that were powered up, at the time (assuming they
aren't actively "doing something" that will take a fair amount
of time -- like rendering a 3D model, "make world", etc.);
examine each open application so I can return to that state
when power is eventually restored.

(I typically leave a machine exactly where it was when I was
last using it so the display reminds me as to what I was doing)

Also, shut down any network appliances or headless servers
in an orderly manner. etc.

Or, hope the batteries in each UPS are stiff enough to
carry the loads for the time you *expect* to need to swap
out the breaker.

I.e., I have to do a fair bit of planning if I want to remove
power for anything more than a few seconds (which I expect
the UPS's to always handle even when batteries are toast).

but you have to do that if your home has a power failure

I have no control over a power failure. I *do* have control
over when -- and IF -- I remove power to do electrical
maintenance!
If it's the "Old CH" I'm thinking of, I'd be replacing it. It
wouldn't stand a chance of passing code up here as a new install. NO
conductors from the "switched" side are allowed into the "main" side
of the panel. None. Period.