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Posted by Bill on August 23, 2008, 8:32 am
The GFI is probably working just fine and doing its job. These detect when
there is a short to ground. Electric motors have all sorts of exposed wires
inside and dust can get in there and cause a little short to ground.
Try blowing out the fan motor with compressed air or having the motor
serviced.
> Hello Group.
>
> I have a problem with a GFCI tripping every time I turn on my shop
> fan. This line has a 40" shop fan (on a wall switch) and three
> outlets. I can use the outlets fine, but when I turn on the fan, it
> runs for about ten seconds and then it trips the GFCI. It was wired
> by a licensed electrician and worked fine for ten years. What is the
> best way to figure out what's bad, the fan motor, the GFCI, or maybe
> the breaker? Any advice?
>
> Thanks.
>
> unklerichie
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Posted by beecrofter on August 23, 2008, 11:36 am
> The GFI is probably working just fine and doing its job. These detect whe=
n
> there is a short to ground. Electric motors have all sorts of exposed wir=
es
> inside and dust can get in there and cause a little short to ground.
>
> Try blowing out the fan motor with compressed air or having the motor
> serviced.
>
>
>
> > Hello Group.
>
> > I have a problem with a GFCI tripping every time I turn on my shop
> > fan. =A0This line has a 40" shop fan (on a wall switch) and three
> > outlets. =A0I can use the outlets fine, but when I turn on the fan, it
> > runs for about ten seconds and then it trips the GFCI. =A0It was wired
> > by a licensed electrician and worked fine for ten years. =A0What is the
> > best way to figure out what's bad, the fan motor, the GFCI, or maybe
> > the breaker? =A0Any advice?
>
> > Thanks.
>
> > unklerichie- Hide quoted text -
>
> - Show quoted text -
Blowing out a motor with compressed air is a quick way to be buying
it's replacement.
Soft paint brush and a vacuum , and yes you sometimes have to open the
thing up.
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Posted by Steve Barker DLT on August 23, 2008, 2:46 pm
OH PLEEEEEASE....... I've been blowing motors out for 40+ years and have
NEVER damaged one yet. You'll do more damage poking a vacuum nozzle or
paint brush in there.
s
Blowing out a motor with compressed air is a quick way to be buying
it's replacement.
Soft paint brush and a vacuum , and yes you sometimes have to open the
thing up.
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Posted by TWayne on August 24, 2008, 11:36 am
> Hello Group.
>
> I have a problem with a GFCI tripping every time I turn on my shop
> fan. This line has a 40" shop fan (on a wall switch) and three
> outlets. I can use the outlets fine, but when I turn on the fan, it
> runs for about ten seconds and then it trips the GFCI. It was wired
> by a licensed electrician and worked fine for ten years. What is the
> best way to figure out what's bad, the fan motor, the GFCI, or maybe
> the breaker? Any advice?
>
> Thanks.
>
> unklerichie
A 40" fan has to have a pretty good sized motor and takes several
seconds for it to come up to speed. Everything being reactive, while it
is starting, it is creating reverse EMF (electro-motive-force) which,
during that time, is making the current in the two feed wires go out of
phase with each other. THAT can pop a GFCI; they just don't work well
with large inductive loads like electric motors.
Please let us know if changing out the GFI helps anything because IMO it
won't, but I'd be pleased to be wrong.
Also, if the insides of the fan are dirty, dusty, full of fuzz and
coated with whatever from the air, that can cause small currents to flow
from the hot to the earth ground which might also trip a GFCI.
It sounds like the fan gets turning pretty good before the GFI pops, so
you could, JUST IN THIS ONE CASE, try starting the fan, when the GFI
pops, quickly reset it and see if the fan will continue to start up.
If it still pops, you could try VERY CAREFULLY (ELECTRICITY CAN
*KILL* YOU) TRY shorting around the GFCI with a lead until the fan gets
running. Then remove the bypass; If the fan continues to run, there is
there is no problem with the fan. \
But if the GFCI pops, then there is definitely a probelen with the
fan or the wiring to it.
I'd use a little Radio Shack clip lead to do the shorting across the
GFCI (from input/source side to load side, NOT load to load!).
Kill the breaker, put the clip leads on, have somoeone turn on the
breaker, carefully remove the clip lead by the insulated handles, and
see if the fan keeps going. If so, it's 99% going to be EMF issues
which most any GFCI will pop on.
Note: If the GFCI should pop while the clip leads are attached, it
means one of them is not getting a good connection; kill power, clean
the area you want to attach it to, and try again.
DONE WRONG, THIS CAN BE VERY DANGEROUS! NEVER TOUCH ANYTHING ELECTRICAL
OR ANY METAL NEAR THE ELECTRICAL PART WHILE THE BREAKER IS ON! If you
aren't experienced around electricity see if you can find an
experienced buddy to do these things for you; it might be the best
advice.
BTW, GFCI's are down in cost these days and there ARE some that are made
for higher loads than the standard 15 amps, although they cost more.
HTH
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Posted by M Q on August 24, 2008, 2:00 pm
TWayne wrote:
...
>
> A 40" fan has to have a pretty good sized motor and takes several
> seconds for it to come up to speed. Everything being reactive, while it
> is starting, it is creating reverse EMF (electro-motive-force) which,
> during that time, is making the current in the two feed wires go out of
> phase with each other.
B.S. Unless you have a very big reservoir for electrons, the current
on the two feed wires will not be "out of phase".
A large capacitor to ground would be such a reservoir, but that is
a ground fault, and the GFCI should trip for that.
...
> If it still pops, you could try VERY CAREFULLY (ELECTRICITY CAN
> *KILL* YOU) TRY shorting around the GFCI with a lead until the fan gets
> running. Then remove the bypass; If the fan continues to run, there is
> there is no problem with the fan.
Not necessarily. There may be both mechanical and electrical
differences in the motor during acceleration that could cause
a ground fault during acceleration. OP didn't mention whether
this motor had a centrifugal switch controlling the start winding.
Most likely you have a ground fault in the motor.
It may be solid or it may be intermittent.
Have you tried measuring the resistance from hot to ground
for the motor?
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Page 2 of 3 < 1 2 3 > last >>
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