I have to admit, I'm a little skeptical about the double-pole switch.
Whether resistive or inductive, how can you have current flow unless the
circuit is completed? Open the hot wire and current shouldn't flow through
the neutral either, unless there really was a fault in the wiring
somewhere? I was an electronic tech MANY years ago, so maybe I've just been
away from this stuff too long. :)
In any case, my own attempts at solving the problem have failed, so I'm
willing to give it a try. I bought a double-pole switch yesterday ($9) and
plan to install it in the next day or two. Unfortunately, due to the
erratic nature of the problem, I may not know for a month or more whether
it solved the tripping problem. But, if it does trip again, at least I can
rule out the switch once and for all.
Thanks for the feedback!
You basically have a 2 wire inductor. You are saying that when the
circuit is broken, magnetic field collapse produces a current flow in
one wire that is not equal to the current flow in the other wire. You
may be in line for a Nobel Prize. Or maybe not.
I think that YOU need to pay attention:
In the wire that is not connected we can agree that the current is zero?
In the wire that is connected, what do you think the current is?
If it is zero, they are equal and the GFCI should not trip.
If it is not zero, where do you think that current is going?
Those electrons have to go (come from) somewhere. They are not
getting stored in the fan. They could be going to ground, but
only if you have a ground fault.
Sorry for the potentially redundant post but......
Since the GFI is tripping we know that somehow the currents compared
by the GFI's circuit are different; the hot is zero since the switch
is open, thus the current at on the neutral is non-zero.
It's going from the fan collapsing field thru the neutral wire back to
the neutral / ground bus at the service panel.
Actually, they're kinda stored "stored in the fan"......in the
magnetic field, while the fan is running.
They are going to ground, but not thru a fault....but thru the neutral
MQ, this is just my understanding of how motors & GFI can
interact......... I could be wrong but I believe this is a reasonable
Any current produced in this way will be way too small to trip the
GFCI. The capacitance to ground of the now open hot wire bewteen the
motor and the switch is way too small to support the required current.
If this theory was correct then the GFCI could be made to trip by
applying line voltage across the motor from a separate branch circuit,
one on the same leg, while the switch is open. Back emf is voltage,
Though I applaud the effort.
How about static discharge from their finger to the switch when they
go to turn it off?
I considered that, but the GFCI trips even if I just touch the switch
handle (no metal conductive parts).
It will sometimes also trip three or four times in a row. Trip, reset,
trip, reset, etc. Then it'll go several weeks without tripping again.
The GFCI, switch, wiring, and fan are all new. I've already replaced the
GFCI and switch to rule those out as faulty. Everything is properly wired
My in-laws live out of town so I don't get up that way very often, but I'm
going to try the double-pole switch on our next visit. If that fails, it
has to be a faulty fan, or a problem with the wiring.
Actually it sounds like a wiring issue. Conductors have an inductive/
capacitive link between them. If you have a stray conductor running a
different load that is close to and parallel to the wires feeding the
fan motor, then you'll get a current imbalance through the GFCI.
On Jan 1, 10:32 am, firstname.lastname@example.org (Doug Miller) wrote:
Maybe the two effects (motor generator action, and capactive bleeding
to ground) are combining thier efforts to trip the GFCI. I don't
know. But I do know there are millions of GFCI's out there that don't
trip when a motor connected to them is turned off. I also know that
if you run more than about 250 ft of extension cord that the
capacitive coupling between the hot wire and the ground wire will
cause the GFCI receptacle that you have it plugged into to trip.
Capacitive/inductive coupling can lower the GFCI's tolerance by
providing a continuous background leakage. If the GFCI is rated to
trip at .X amps, then capacitive leakage to ground can reduce that
trip current to a small fraction of .X. Any spurious signal is likely
to cause a trip at that point, even the neighbors ham radio.
Nope, other than where the cable exits the switch box, there are no other
cables anywhere near the cable running to the ceiling fan.
Also, the fan NEVER trips while running, only when it is turned OFF. And
even then, it's only once every few weeks or so.
The fan isn't required to be on a GFI protected circuit unless it is in the
shower/tub space. I'm not sure what could be causing your problem. Maybe
try installing a two pole switch so that the hot and the neutral are being
disconnected at the same time.
Well, good to know, but a little too late. It had been my understanding
that the entire bathroom circuit needed to be protected by the GFCI. But
the inspector mentioned a couple of things that didn't need to be on it
also. Oh well, no harm done, except for the fan nuisance.
The DPST switch idea sounds like my best option if I can find one.
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