In my garage I have a 20 Amp circuit which has two 15 amp GFCI outlets.
On this same circuit these are also two GFCI's in the kitchen and
another in a bathroom. My problem is that I have a radial arm saw
which apparently draws too much current in starting up resulting a
tripped GFCI and i can't run the saw. The book that came with the saw
says that there should be "a time delay 15 amp circuit breaker
installed." I'm not sure that GFCI outlets were installed when this
saw was made. An inquiry at an electric supply store resulted in the
information that there is no such thing as a time delay GFCI." My
question is, since it is a 20 amp circuit can I replace the 15 amp GFCI
with a 20 amp one, and will this solve the problem of starting the saw
I'm not an electrician but my table saw used to trip the breaker until I
started using a 12ga extension cord on it. But even though it was on a GFCI
circuit, it never tripped that but would trip the breaker in the main box.
Sounds like you may have a slight ground problem with the saw. I'm not
qualified to answer your question, however, just relating my experience.
Yes, you can have a 15 amp GFCI outlet on a 20 AMP breaker, as long as
the wire is 12 gauge. But what does sound a little strange is that he
appears to have 5 GFCI's on the same circuit. One GFCI can protect
not only the outlet it is installed in, but also the downstream
outlets. Or a single GFCI breaker could protect all of them.
As to whether going to a 20 amp GFCI outlet would help, I think the
answer is no. GFCI outlets are tripped by ground faults, not normal
hot to neutral current that exceeds the outlet rating. In fact, as far
as I know, none of the GFCI outlets check for excess current at all.
Having a large inductive load on an GFCI is not recommended because in
some cases they can cause the type of tripping problems the OP is
As Trader said, it's normal to have 15 amp GFCI's on a 20 amp circuit as the
"feed through of a 15 amp GFCI is rated for 20 amp and kitchen outlet
circuits should not be on with any other circuits except dining room
outlets. Ground fault outlets are not circuit breakers, so if the outlet is
tripping, it would be caused by a "ground fault" not an overloaded circuit,
which would cause the circuit breaker to trip
I just realised we never came up with a solution for the OP. Assuming
the radial arm saw doesn't have a real ground fault, then I see a
couple of possible solutions. He needs to get the saw off of a GFCI.
Now I know code says outlets in a garage need to be on a GFCI, but what
about if the saw could be wired in directly, instead of plugged into an
outlet? Is that exempt from needing a GFCI? If so, he could wire the
garage so the outlets are on GFCI, but the saw is not.
Alternatively, he could make the one outlet the saw is plugged into
non-GFCI, while leaving the rest of the garage outlets GFCI. That is
a code violation, however if it were my garage, and the only reasonable
way to do it, I would consider it. I'd also make sure the saw was
properly grounded, plug up the other outlet on the receptacle, and put
up a warning label.
I think the key is that, as another poster pointed out, some GFCIs
are more tolerant of inductive loads than others, so a bit of
experimentation could be warranted. Power factor correction on the
motor might also help. Unfortunately, either option could cost more
than a new saw, depending on the saw.
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Regarding GFCI tripping, replacing the outlet is a good
I just had a GFCI in the kitchen start to trip when using the
microwave. Since the microwave worked on another GFCI circuit,
I just replaced the outlet.
So far, so good.
I think you are a bit confused here about the function of a GFCI. A GFCI
tripping has nothing to do with how many amps are being used on the circuit.
That is what the breaker in your main panel is for.
The GFCI will only detect a current imbalance between hot and neutral.
If some current is going somewhere else like through you to ground then the
It is not uncommon for GFCI's to false trip with large motors or compressors
in things like power tools, large appliances etc. This is why code allows
you to put your refrigerator on a non GFCI outlet.
Some GFCI's brands/models are worse than others at false trips. If your
GFCI's are pretty old then try replacing the one you use for the power saw
with a new one and see if that helps.
It may be the power saw that has the problem The tool may be defective. But
some older tools just won't work on a GFCI.
Using a 20 amp GFCI will not make a difference. The 20 amp rating is only
the configuration of the plug that the outlet will accept. If you don't
have any 20 amp appliances with the one horizontal blade | -- then it does
not matter. I think all GFCI's are made to feed thru 20 amps in the wires.
The 15 amp version will not accept a 20 amp plug, which is pretty rare to
have in the home.
If the breaker in your panel is not tripping then I would just leave it
alone. If you do replace it don't change the 20 to a 15 just because the
power saw manual specified that. That is a min. spec. If you must replace it
then get a 20 amp if that is what you have.
You would be better off running a dedicated circuit to your garage.
Newer construction would have 3 dedicated circuits min. where you have only
one. (one to bath, one + to kitchen, one to garage). However a dedicated
circuit may not help the GFCI tripping unless other items plugged into the
same circuit are contributing to the problem.
The NEC did allow a dedicated appliance outlet to exist without GFCI
protection. A single-outlet (Hubbell twist-lock comes to mind) could
serve the appliance (saw) as long as it did not serve plug-in hand
I have been retired for several years and NEC has probably changed
some. Check with your Authority Having Jurisdiction or a knowledgeable
No. Are you sure it didn't say "time delay _fuse_ OR circuit breaker"?
When using fuses, a time delay fuse is needed for large motors.
Circuit breakers are inherently time delay.
If the GFCI is tripping all the time, you have some sort of electrical leak in
It's sufficiently _uncommon_ that you will definately not see a GFCI trip
every time you try to turn on a motor.
The saw has a leak. Needs to be checked.
I bought a RAS at an auction some years back. It would have tripped a GFCI
if I had one in the garage. The ground wire in the electrical plug had
come adrift from the screw and was contacting the hot wire. The whole
frame went live. Used it several times until I noticed a slight tingle
when touching it. H'm, then touched another grounded tool at the same time.
I'm smarter now ;-)
Chris Lewis, Una confibula non set est
It\'s not just anyone who gets a Starship Cruiser class named after them.
Are you sure the manual was not referring to fuses? Fuses come in quick blow
or time delay types.
Sometimes the manuals will try to cover all possible cases the user might
find. ie breakers and/or fuses. If your home had fuses then you may need to
get the time delay type for the saw anyway.
Even then I would not get the time delay fuses unless it actually blew out
I think you can get time delay breakers but HD and such may have to special
As I said in my reply if your breaker is not blowing with the saw then don't
bother to replace it. If you do replace it, (with a time delay type), then
you would need the 20Amp breaker. I think that is what your said you had..
If you put a 15 then you might find that other stuff in the house will
overload and blow it. I am assuming that all your wiring is 12ga.
The reason no one commented on the time delay breaker is that it won't
solve your problem. You have a GFCI tripping do to either a real
ground fault or do to the high inductance load of the saw. If it were
the breaker tripping do to high start up current, that would be a
"My problem is that I have a radial arm saw
which apparently draws too much current in starting up resulting a
tripped GFCI and i can't run the saw."
GFCI dont trip due to overcurrent, they trip due to 'ground fault.'
"The book that came with the saw says that there should be 'a time delay
15 amp circuit breaker installed.'"
You have a 'time delay 15 amp circuit breaker' as home circuit breakers
are all time delay.
"An inquiry at an electric supply store resulted in the information that
there is no such thing as a time delay GFCI."
You were sent to the store to ask for time delay 15amp circuit breaker
but instead you ask for time delay GFCI??? Silly as that is, if there
were such a thing it would probably solve your problem, lol.
As someone pointed out, your saw manual probably tells you what kind of
extension cord you can use. be sure to follow that direction.
you can also post to rec.woodworking and they will have tips too since
they use power saws a lot over there.
"Then said I, Wisdom [is] better than strength: nevertheless the poor
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