No problem Calvin, I'm always open to anyone with a
good point or better observation.
Inline:
"Calvin Henry-Cotnam"
wrote in message
...
Pop ) said...

Umm, no, they do NOT do that "sometimes" if
everything
is installed correctly. Sorry, don't mean to sound
confrontational, but a GFCI tripping is an indication
that something went wrong whether it was water or
whatever that caused it to trip. They don't "just do
that" for no reason. They would be useless in such a
case.

Sorry to burst this bubble, but GFCIs can trip for
what *appears*
to be "no reason", and this is why codes never make
them manditory
for outlets used for refrigerators.
=== A GFCI, one which is built to NA standards as
requied by law, monitors the difference in current
between the hot and the neutral wires. Whenever that
current varies too much, I think it's about ten
milliamps, the thing trips and turns off the power.
IMO, he was given a glib, and wrong, response by that
person.

Transient noise on a power line can cause GFCIs to
trip, however
I suspect it would be EXTREMELY rare for such noise
to trip a
GFCI that did not have a load on it at the time.
=== It would be fairly rare in any instance, but
moreso as you indicated. By the time a spike makes it
through the transformer on the pole, and all the
inductance in that xfmr, there isn't much of it left
for the house wiring, which in turn has a substantial
sinking ability due to the things plugged into it.
I'd be willing to bet money that no transient was at
work in this picture; it just doesn't fit the anecdotal
evidence.

Since the original
poster mentioned lights that stopped working, it
sounds to me that the
lights are downstream from the GFCIs and could
possibly have been a
load on it when a transient (spike) hit it.
=== Now, that's a distinct possibility. In fact, I
mentioned it in a post a few minutes back that I'd
neglected to consider that. If that's the case, then
there was an obvious reason for it tripping that anyone
worth their salt could have asked about, instead of
just that "they do that".

Transients are high frequency noise on the power
line, and high frequencies
propogate slowly (relative to the speed of light)
down a transmission line,
which the power line would serve as. GFCIs work by
detecting a difference
in current between the line and neutral. The slow
propogation of a spike
can lead to a sensitive GFCI to detect an imbalance
long enough for it to
trip.
Umm, no, not really. High frequencies first of all
wouldn't make it thru the network into the home wiring
and if it was powerful enough to make it thru via
arccing or whatever in the xfmr, it's not "noise".
There is a lot of "noise" on any of those power lines;
it's the design of the lines that protects it from
getting into the houses. Else, anyone with a modem
could pick off the billing information, all kinds of
data that are also flowing up and down those wires.
Any signals on those wires cancel themselves and
anything left is further reduced by the turns ration in
the transformers. There is even a reason for the
spacing between power lines, in fact, that comes into
play. You can only decode data AT th epower lines
termination points. By design, any outside noise is
also going to be horizontally applied, and will again
be self-damped. It's called longitudinal balance. I
used to work on that kind of equipment. It's
interesting stuff, actually, since few people know it's
there. Electrical and gas consumption billing are two
typical applications and anything from lightning to the
sun can induce noise into the lines, but due to design,
it's reduced to the point where it has no afffect on
things.


This would *appear* as a "no reason" trip, yet there
is a reason. It
is just not a safety reason.
=== You cannot say that. The gfci tripped, and the
reason isn't known. You can not know whether there
would be a dangerous fault or not if the GFCI hadn't
been there.

I once knew someone who had a pool pump on a GFCI and
claimed that
every lightning storm his pool was "hit by lightning"
because the GFCI
would trip. LOL -- if his pool was hit, his problem
would be a lot
greater than just resetting the GFCI! The electrical
storm was causing
transients on the power lines in the area that were
the cause of the GFCI
tripping.
=== Like I said, that's possible, but very unlikely to
be the problem, given the information available so far
in this post. Since we're now going into empirical,
anecdotal eveidence, I have a GFCI on my pool pump,
too, because I also run the pool lights from it. Then
that receptacle goes off to another receptacle/switch,
which is used for the yard lighting. It has NEVER
tripped before, during, or after a storm. The only
time it's ever tripped was when I pressed the test
switch, or stuck a resistor between the conduit and the
receptacle.
There are some valid reasons why some of the larger
horsepower motors will cause them to trip, but it's not
the noise generated. It's the pase shift caused by the
inductance in the motors, especially when they're
capacitor starts instead of clutch-started. Either
way, the currents in the live/neutral vary sufficiently
for the GFCI to detect the current difference, and thus
it trips. I recall the last one I bought, a portable,
had a reaction time in the micro-second range; that's
pretty fast when you consider you're working with a
period of what, about 16 mS on 60 Hz?
I don't think any of that's relevant to the OP's
situation.

However, I DO think your comment about something
plugged in at the time of the rain or, whenever the
thing opened, is important, since it wasn't
specifically noted one way or the other by the OP.
That installer sounds either incompetent or sort of,
uhh, dishonest and doesn't care since he came up with
"they do that".

Cheers,

PopS


--
Calvin Henry-Cotnam
"Never ascribe to malice what can equally be
explained by incompetence."

- Napoleon
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