Mike Hennessey wrote:
On Mon, 21 Jan 2008 13:15:26 -0600, HerHusband
wrote:

It's possible that this particular GFCI is a little more sensitive
than it should be, and swapping it with a different one may cure the
problem.
Switching both the hot and the neutral through a double-pole switch is
almost certain to fix it.
Well, it was worth a try, but the DPST switch did not fix the problem
either. It worked fine for about two weeks, then tripped again a couple of
days ago.

As always, it trips when the fan switch is turned "OFF", not while it is
running.

I've tried two different GFCI's, and three different switches, and they all
have the same results.

I'm baffled. The wiring is new and in good condition. The only two things I
can think are the fan itself is bad, or condensation is draining back into
the fan and causing problems.

Still, it seems like the DPST switch would completely isolate the fan from
the GFCI. There shouldn't be any current flow even if there was a problem
with the fan. And there have been absolutely no problems while it is
running. Only when it is turned off.

Other than rewiring to take the fan off the GFCI, or replacing the fan, are
there any other things I could try?

Anthony



I have a similar problem. I noted that when the light bulb on the fan
fixture is illuminated the problem does not occur. Perhaps a
resistive load across the fan absorbs any power line spikes which
trip the GFCI. Just an idea.


I suggested earlier the high voltage spike that can be produced in the
fan winding when the switch is turned off could produce capacitive
currents from the fan winding the motor poles (ground). The size of the
spike depends on where in the sine wave the fan is turned off - random
effect. Fans intended to be used on GFCI circuits could be built with
more winding isolation. I haven't seen aanswer yet that better fits what
happens.

In Mike's description above, if the light is connected across the fan
when the fan is turned off the light could absorb part of the spike from
the motor winding.

I don't think there is a fix other than "take the fan off the GFCI, or
replacing the fan".

--
bud--