The outlets in the back of the house are on a 20A GFCI.
(Note to self: are there any other outlets on that same
circuit that I need to chase down?)

Presently using them to light XMAS lights on one of the
citrus trees. IIRC, each string is about 250W. With
~700W on the circuit, turning the breaker ON (i.e., using
it as a switch -- instead of plugging/unplugging the
load) causes it to immediately trip. Repeating the
action in short order appears to get it to latch and
remain latched (ON), indefinitely.

OK, so the surge when all the lamps are cold can increase
the inrush current -- on the short term -- to levels that
probably exceed the 20A limit of the breaker.

"In theory"

OTOH, in years past, I've run the circuit at close to its
capacity (~10 strings) without this problem.

I've changed breakers (swapped with one feeding another
circuit) and the problem persists.

[There are no leakage paths in the wiring OUTSIDE]

This suggests something in the wiring/fixtures. I'll
start isolating outlets, tomorrow (dark here, now).
Perhaps some insect (leaf cutter?) has opted to nest
in one of the receptacles.

Anything else I should explore?

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.

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"

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

The outlets in the back of the house are on a 20A GFCI.
(Note to self: are there any other outlets on that same
circuit that I need to chase down?)

Presently using them to light XMAS lights on one of the
citrus trees. IIRC, each string is about 250W. With
~700W on the circuit, turning the breaker ON (i.e., using
it as a switch -- instead of plugging/unplugging the
load) causes it to immediately trip. Repeating the
action in short order appears to get it to latch and
remain latched (ON), indefinitely.

OK, so the surge when all the lamps are cold can increase
the inrush current -- on the short term -- to levels that
probably exceed the 20A limit of the breaker.

"In theory"

OTOH, in years past, I've run the circuit at close to its
capacity (~10 strings) without this problem.

I've changed breakers (swapped with one feeding another
circuit) and the problem persists.

[There are no leakage paths in the wiring OUTSIDE]

This suggests something in the wiring/fixtures. I'll
start isolating outlets, tomorrow (dark here, now).
Perhaps some insect (leaf cutter?) has opted to nest
in one of the receptacles.

Anything else I should explore?

Since you are swapping stuff around, try it on a non-GFI circuit. That
will tell you if it is a ground fault.
Usually this tracks back to water/bugs in a box.

I have one nightmare GFI circuit here that is longer than the design
spec for GFIs but it works when everything is dry. When it fails, I
end up splitting the circuit up to isolate the failure. Bear in mind,
it can be a ground fault on the neutral.
On outside boxes, make sure all of the wirenuts are pointed up, near
the top of the box and that they are not too close to the box. It
mitigates the water they all collect eventually.

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.

On 12/1/2015 7:46 PM, 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?

Appears not to. OTOH, it won't trip with smaller loads.

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"

The problem is, I can't tell if it is tripping from a momentary
"over current" condition *or* a "leak". The fact that the
circuit *holds* on the second attempt suggests it is related to
the turn on transient (all those ice cold filaments now having
had a chance to warm up -- even only momentarily -- to higher
operating resistances).

Note that the other GFCI breakers have operated flawlessly for
exactly the same length of time -- with more frequent usage
(the outdoor circuit is rarely used) located in the same
(outdoor) electrical panel. That, coupled with swapping breakers
suggests the problem isn't in the breaker (or panel).

I'll try moving the load to a different receptacle and isolating this
portion of the branch circuit. That will require a "longer" extension
cord (actually, the current cord is long enough; I'll just have to
unwind it from its "storage spool") so I will first verify the
"bad" outlet fails with that lengthened cord before trying the
lengthened cord in an upstream outlet.

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

The outlets in the back of the house are on a 20A GFCI.
(Note to self: are there any other outlets on that same
circuit that I need to chase down?)

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.

Presently using them to light XMAS lights on one of the
citrus trees. IIRC, each string is about 250W. With
~700W on the circuit, turning the breaker ON (i.e., using

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


it as a switch -- instead of plugging/unplugging the
load) causes it to immediately trip. Repeating the
action in short order appears to get it to latch and
remain latched (ON), indefinitely.

OK, so the surge when all the lamps are cold can increase
the inrush current -- on the short term -- to levels that
probably exceed the 20A limit of the breaker.

"In theory"

OTOH, in years past, I've run the circuit at close to its
capacity (~10 strings) without this problem.

I've changed breakers (swapped with one feeding another
circuit) and the problem persists.

[There are no leakage paths in the wiring OUTSIDE]

This suggests something in the wiring/fixtures. I'll
start isolating outlets, tomorrow (dark here, now).
Perhaps some insect (leaf cutter?) has opted to nest
in one of the receptacles.

Anything else I should explore?

On Tue, 01 Dec 2015 20:25:06 -0700, Don Y
wrote:

I'll just have to
unwind it from its "storage spool")

Try just unwinding it from the spool and trying it again. You may just
be coupling current into the grounding conductor.

Because of that, they do have specs for different wiring methods and
the total length of the circuit.

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!

On 12/1/2015 8:55 PM, wrote:
On Tue, 01 Dec 2015 20:25:06 -0700, Don Y
wrote:

I'll just have to
unwind it from its "storage spool")

Try just unwinding it from the spool and trying it again. You may just
be coupling current into the grounding conductor.

Because of that, they do have specs for different wiring methods and
the total length of the circuit.

Again, nothing changes on the spool between the first breaker closure
(that trips) and the second (that holds).

Same extension cord used in previous years. Tree is in the same location
that it was -- as is the electrical outlet (i.e., so, no more or less
cord on the reel than in past years). Same strings of lights (though far
FEWER of them). Same ambient temperatures. etc.

I'll have to play with it some more to get a better characterization
of how it behaves (different size loads, different TYPES of loads, how
long the circuit needs to "rest" before the problem will reproduce, etc.)

On 12/1/2015 7:57 PM, wrote:
On Tue, 01 Dec 2015 19:19:01 -0700, Don Y
wrote:

The outlets in the back of the house are on a 20A GFCI.
(Note to self: are there any other outlets on that same
circuit that I need to chase down?)

Presently using them to light XMAS lights on one of the
citrus trees. IIRC, each string is about 250W. With
~700W on the circuit, turning the breaker ON (i.e., using
it as a switch -- instead of plugging/unplugging the
load) causes it to immediately trip. Repeating the
action in short order appears to get it to latch and
remain latched (ON), indefinitely.

OK, so the surge when all the lamps are cold can increase
the inrush current -- on the short term -- to levels that
probably exceed the 20A limit of the breaker.

"In theory"

OTOH, in years past, I've run the circuit at close to its
capacity (~10 strings) without this problem.

I've changed breakers (swapped with one feeding another
circuit) and the problem persists.

[There are no leakage paths in the wiring OUTSIDE]

This suggests something in the wiring/fixtures. I'll
start isolating outlets, tomorrow (dark here, now).
Perhaps some insect (leaf cutter?) has opted to nest
in one of the receptacles.

Anything else I should explore?

Since you are swapping stuff around, try it on a non-GFI circuit. That
will tell you if it is a ground fault.

Moving the strins of lights to another circuit would take the
existing wiring *and* GFCI out of the calculus.

OTOH, I could see if there's a breaker nearby that I can
"borrow" onto which to move the existing wiring. I.e.,
I've tried changing JUST the GFCI breaker with another
GFCI breaker (keeping everything else constant); this would
allow me to try nonGFCI vs. GFCI (again, keeping everything
else constant).

Trick will be to see how far I can reach in the electric panel
to pick up a different breaker.

Usually this tracks back to water/bugs in a box.

Boxes are recessed into block/cement walls. Faces sealed with
foam gaskets. Outdoor "in use" covers keep out direct rain/water.

Bugs, OTOH, can always crawl in through the hole in the cover intended
for the cords to exit.

But, bug would lead to suspected GFCI issue. And, would persist
(not "clear" itself after the first breaker trip/reset)

I have one nightmare GFI circuit here that is longer than the design
spec for GFIs but it works when everything is dry. When it fails, I
end up splitting the circuit up to isolate the failure. Bear in mind,
it can be a ground fault on the neutral.

Again, see above. IMO, it has something to do with the initial
transient. I need to find a load that is more PURELY resistive
to see what it's like when the load is X from the moment the
breaker is FIRST closed.

On outside boxes, make sure all of the wirenuts are pointed up, near
the top of the box and that they are not too close to the box. It
mitigates the water they all collect eventually.

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

The outlets in the back of the house are on a 20A GFCI.
(Note to self: are there any other outlets on that same
circuit that I need to chase down?)

Presently using them to light XMAS lights on one of the
citrus trees. IIRC, each string is about 250W. With
~700W on the circuit, turning the breaker ON (i.e., using
it as a switch -- instead of plugging/unplugging the
load) causes it to immediately trip. Repeating the
action in short order appears to get it to latch and
remain latched (ON), indefinitely.


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].

OK, so the surge when all the lamps are cold can increase
the inrush current -- on the short term -- to levels that
probably exceed the 20A limit of the breaker.


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.

"In theory"

OTOH, in years past, I've run the circuit at close to its
capacity (~10 strings) without this problem.

I've changed breakers (swapped with one feeding another
circuit) and the problem persists.

[There are no leakage paths in the wiring OUTSIDE]

This suggests something in the wiring/fixtures. I'll
start isolating outlets, tomorrow (dark here, now).
Perhaps some insect (leaf cutter?) has opted to nest
in one of the receptacles.

Anything else I should explore?

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.

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!
Unless the first application of power heated and "dried" whatever
was causing the leak. Not a very likely scenario, for sure - but
possibly just within the realm of possibility??

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

On 12/1/2015 7:57 PM, wrote:
On Tue, 01 Dec 2015 19:19:01 -0700, Don Y
wrote:

The outlets in the back of the house are on a 20A GFCI.
(Note to self: are there any other outlets on that same
circuit that I need to chase down?)

Presently using them to light XMAS lights on one of the
citrus trees. IIRC, each string is about 250W. With
~700W on the circuit, turning the breaker ON (i.e., using
it as a switch -- instead of plugging/unplugging the
load) causes it to immediately trip. Repeating the
action in short order appears to get it to latch and
remain latched (ON), indefinitely.

OK, so the surge when all the lamps are cold can increase
the inrush current -- on the short term -- to levels that
probably exceed the 20A limit of the breaker.

"In theory"

OTOH, in years past, I've run the circuit at close to its
capacity (~10 strings) without this problem.

I've changed breakers (swapped with one feeding another
circuit) and the problem persists.

[There are no leakage paths in the wiring OUTSIDE]

This suggests something in the wiring/fixtures. I'll
start isolating outlets, tomorrow (dark here, now).
Perhaps some insect (leaf cutter?) has opted to nest
in one of the receptacles.

Anything else I should explore?

Since you are swapping stuff around, try it on a non-GFI circuit. That
will tell you if it is a ground fault.

Moving the strins of lights to another circuit would take the
existing wiring *and* GFCI out of the calculus.

OTOH, I could see if there's a breaker nearby that I can
"borrow" onto which to move the existing wiring. I.e.,
I've tried changing JUST the GFCI breaker with another
GFCI breaker (keeping everything else constant); this would
allow me to try nonGFCI vs. GFCI (again, keeping everything
else constant).

Trick will be to see how far I can reach in the electric panel
to pick up a different breaker.

Usually this tracks back to water/bugs in a box.

Boxes are recessed into block/cement walls. Faces sealed with
foam gaskets. Outdoor "in use" covers keep out direct rain/water.

Bugs, OTOH, can always crawl in through the hole in the cover intended
for the cords to exit.

But, bug would lead to suspected GFCI issue. And, would persist
(not "clear" itself after the first breaker trip/reset)

I have one nightmare GFI circuit here that is longer than the design
spec for GFIs but it works when everything is dry. When it fails, I
end up splitting the circuit up to isolate the failure. Bear in mind,
it can be a ground fault on the neutral.

Again, see above. IMO, it has something to do with the initial
transient. I need to find a load that is more PURELY resistive
to see what it's like when the load is X from the moment the
breaker is FIRST closed.

On outside boxes, make sure all of the wirenuts are pointed up, near
the top of the box and that they are not too close to the box. It
mitigates the water they all collect eventually.

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.

On Wed, 02 Dec 2015 03:35:57 -0600, wrote:

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

The outlets in the back of the house are on a 20A GFCI.
(Note to self: are there any other outlets on that same
circuit that I need to chase down?)

Presently using them to light XMAS lights on one of the
citrus trees. IIRC, each string is about 250W. With
~700W on the circuit, turning the breaker ON (i.e., using
it as a switch -- instead of plugging/unplugging the
load) causes it to immediately trip. Repeating the
action in short order appears to get it to latch and
remain latched (ON), indefinitely.


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].

OK, so the surge when all the lamps are cold can increase
the inrush current -- on the short term -- to levels that
probably exceed the 20A limit of the breaker.


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.

"In theory"

OTOH, in years past, I've run the circuit at close to its
capacity (~10 strings) without this problem.

I've changed breakers (swapped with one feeding another
circuit) and the problem persists.

[There are no leakage paths in the wiring OUTSIDE]

This suggests something in the wiring/fixtures. I'll
start isolating outlets, tomorrow (dark here, now).
Perhaps some insect (leaf cutter?) has opted to nest
in one of the receptacles.

Anything else I should explore?

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.

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!!

On 12/2/2015 5:29 AM, wrote:

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!
Unless the first application of power heated and "dried" whatever
was causing the leak. Not a very likely scenario, for sure - but
possibly just within the realm of possibility??

frown I'm at a loss. If there was a "partial short" (leak) that
somehow cleared itself, then I wouldn't expect it to return hours
later -- and the same scenario play out again. And, again.

I need to get out a watch and see how long I can wait *after* the
first breaker close before the *next* closing will NOT hold.
I.e., how long it takes the "problem" to reappear.

It it's on the order of a few minutes, it's unlikely that there's a
"partial short" (dead bug, etc.).

Note that this is a dry time of year for us -- it's not like there
are any external (or internal!) sources of water/moisture (other
than body fluids of bugs : )

On 12/2/2015 5:36 AM, wrote:

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

"plug" -- "outlet"

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.

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.

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.

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.

On 12/2/2015 7:36 AM, wrote:
So there are 3 strings of lights?

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.

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.

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...

On 12/2/2015 7:55 AM, bob haller wrote:
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.

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).

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. 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

On Wed, 02 Dec 2015 07:29:45 -0500, 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!
Unless the first application of power heated and "dried" whatever
was causing the leak. Not a very likely scenario, for sure - but
possibly just within the realm of possibility??

I have lots of GFCIs around here and it is not unusual to have one
that tripped to hold after resetting a time or two.
In the end, I always find a fault somewhere, usually something that is
getting wet.

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

On 12/2/2015 7:55 AM, bob haller wrote:
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.

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).


What happens if the breaker is already on and you just plug in the
lights?

On 12/2/2015 8:39 AM, wrote:
On Wed, 02 Dec 2015 08:07:12 -0700, Don Y
wrote:

On 12/2/2015 7:55 AM, bob haller wrote:
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.

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).

What happens if the breaker is already on and you just plug in the
lights?

The breaker trips. This is one of my least favorite ways of testing
as it means a trip all the way around the house to reset the
breaker... By contrast, turning the breaker on with load attached
gives me the same feedback -- and, I'm right there, ready to turn it
back on, again.

On grumbling about this ("yet another chore on my list") to SWMBO,
she claims she took the toaster oven outdoors some months ago
(WTF?) to "prepare" something and it wouldn't work, either.

I.e., that removes the extension cord and lights from the calculus.

I've removed the breaker from the scenario.

I can (with a bit of work) remove individual duplex receptacles
(leaving the balance of the wiring intact) on the theory that
something is *inside* one of these (leaf cutter, etc.).

[I've started doing this hit-or-miss but need to do so in a
more methodical manner so I can draw conclusions from the
observations]

I can (with a lot *more* work) isolate sections of the wiring
(hard to imagine that being an issue -- it's not routed anywhere
that is likely to see abuse, infestation, moisture, etc.)

I will notice how quickly the problem reappears when I turn
the lights off a bit later this morning -- bulbs having been
lit all night (warm filaments, warm lamp bodies, etc.)

On Wednesday, December 2, 2015 at 10:31:42 AM UTC-5, 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. 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

+1

I also don't think the inrush current on 700W on lights could trip
a 20A breaker. If it could, seems we'd have that problem all the
time. 700W is only 6A worth of lights. I would think it's more
likely something related to a fault, but why it would not happen on
the second attempt, IDK.

On 12/2/2015 11:02 AM, Don Y wrote:
On 12/2/2015 8:39 AM, wrote:
What happens if the breaker is already on and you just plug in the
lights?

The breaker trips. This is one of my least favorite ways of testing
as it means a trip all the way around the house to reset the
breaker... By contrast, turning the breaker on with load attached
gives me the same feedback -- and, I'm right there, ready to turn it
back on, again.


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.

--
..
Christopher A. Young
learn more about Jesus
.. www.lds.org
..
..

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!

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.

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 :

On 12/02/2015 12:08 PM, Don Y wrote:
....

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.

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.

--

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

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.

That's got to be a thermal problem in (probably) a particular lamp...eventually
it'll burn out and let you isolate it or the base itself will fail.

Unplug the three strings from the extension cord. Leave cord
exactly as is. Take three *other* "identical" strings out
and wire them in exactly the same fashion as the first set-of-three.

Turn on breaker. Trips immediately. Let it reset and turn it
on a second time. Holds.

Walk around house to return to the point where the extension cord
is plugged in.

Unplug. Wait a few seconds. Plug back in. Breaker trips.

(No, I'm not going to keep repeating this test to see how long
it takes for the load to "deteriorate" between power applications.
The fact that it tripped suggests the problem is not in the
original three strings of lights -- or, coincidentally ALSO
happens to be in the OTHER three strings, as well. And, no, I'm
not going to drag out a third set of three... or a fourth
set of three... : )

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?

--

On Wednesday, December 2, 2015 at 2:07:56 PM UTC-5, Don Y wrote:
On 12/2/2015 11:54 AM, dpb wrote:
On 12/02/2015 12:08 PM, Don Y wrote:
....

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.

That's got to be a thermal problem in (probably) a particular lamp...eventually
it'll burn out and let you isolate it or the base itself will fail.

Unplug the three strings from the extension cord. Leave cord
exactly as is. Take three *other* "identical" strings out
and wire them in exactly the same fashion as the first set-of-three.

Turn on breaker. Trips immediately. Let it reset and turn it
on a second time. Holds.

Walk around house to return to the point where the extension cord
is plugged in.

Unplug. Wait a few seconds. Plug back in. Breaker trips.

(No, I'm not going to keep repeating this test to see how long
it takes for the load to "deteriorate" between power applications.
The fact that it tripped suggests the problem is not in the
original three strings of lights -- or, coincidentally ALSO
happens to be in the OTHER three strings, as well. And, no, I'm
not going to drag out a third set of three... or a fourth
set of three... : )

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

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)

On 12/2/2015 12:57 PM, wrote:
On Wednesday, December 2, 2015 at 2:07:56 PM UTC-5, Don Y wrote:
On 12/2/2015 11:54 AM, dpb wrote:
On 12/02/2015 12:08 PM, Don Y wrote: ....

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.

That's got to be a thermal problem in (probably) a particular
lamp...eventually it'll burn out and let you isolate it or the base
itself will fail.

Unplug the three strings from the extension cord. Leave cord exactly as
is. Take three *other* "identical" strings out and wire them in exactly
the same fashion as the first set-of-three.

Turn on breaker. Trips immediately. Let it reset and turn it on a second
time. Holds.

Walk around house to return to the point where the extension cord is
plugged in.

Unplug. Wait a few seconds. Plug back in. Breaker trips.

(No, I'm not going to keep repeating this test to see how long it takes
for the load to "deteriorate" between power applications. The fact that it
tripped suggests the problem is not in the original three strings of
lights -- or, coincidentally ALSO happens to be in the OTHER three
strings, as well. And, no, I'm not going to drag out a third set of
three... or a fourth set of three... : )

Seems that the surge current of all those bulbs is just a bit too high for
the breaker.

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

So here's a question...

I assume the lights in question are small incandescent bulbs.

IIRC, they are 9W, miniature base.

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)?

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...

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!

They seem to just be a regular breaker with a GFCI manual trip
mechanism built in.

http://gfretwell.com/electrical/gfci.jpg

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.

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

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!