# Table saw tripping GFCI outlet



## LJD4662 (Sep 29, 2013)

I have an older craftsman 113 table saw with a 13 amp motor that is currently tripping the GFCI outlets in my garage. This problem began about two weeks ago and up until then I have not had any issues. Yesterday I needed to make a few cuts so I ran an extension cord to a non GFCI outlet and ran the saw with no issues. Does anyone have any ideas of what the problem could be? Do I replace the GFCI with another GFCI or go with a regular outlet? Thanks in advance.


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## wapakfred (Jul 29, 2011)

GFCIs can go bad, does it trip with any other tools? If no, I'd say you might want to check your saw for a ground fault….if yes, replace the GFCI. There's probably several other things to check, but you have to start somewhere.


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## dontrushme (Jul 23, 2012)

Just because the saw ran OK in a non-GFCI outlet, and you didn't get a shock, doesn't mean that all is OK. The problem may be a high resistance fault from the hot line to ground.
Check out the GFCI outlet as Fred Hargis suggests.
If the GFCI is OK, then I would first UNPLUG the saw, then turn the power switch on and check the resistance, at the plug, from the hot line/blade to the ground line/pin. After the measurement, don't forget to TURN OFF the power switch. The resistance reading should be infinite, in your case it may not be, which probably means faulty insulation somewhere.
Good luck.


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## jonah (May 15, 2009)

You can test a GFCI outlet with one of those little $5 outlet tester things. They have a button on them that creates a ground fault, which should trip the outlet.

Any hardware store should have them, as do the big orange and blue boxes. I'd try one of those first, to be sure the outlet is functional.


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## MrRon (Jul 9, 2009)

GFCI's do wear out. A table saw may run on 13 amps, but the amperage at start up is now exceeding the GFCI's limit. Either replace the GFCI, or eliminate it altogether. I don't feel a GFCI is necessary in a shop, unless you do your own wiring without good knowledge of electrical circuits. GFCI's are more commonly used in places where moisture is present, like in a kitchen, laundry or bathroom.


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## whope (Sep 15, 2011)

GFI's aren't normally put in unless required by code. A garage floor can easily become damp.

They aren't that expensive so if you need to replace it don't use a regular plug.


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## ChrisK (Dec 18, 2009)

The insulation on the old motor may be going. I have an old craftsman as well, vintage 1950's. The original motor leaked enough voltage that when I touched the saw and the water pipe that was on the wall next the saw you would get a shock. Put on a new motor, no more shocks.

Keep the GFCI!


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## jonah (May 15, 2009)

No properly-working tool should be tripping a properly-functioning GFCI outlet.


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## WhyMe (Feb 15, 2014)

*MrRon replied:* GFCI's do wear out. A table saw may run on 13 amps, but the amperage at start up is now exceeding the GFCI's limit. Either replace the GFCI, or eliminate it altogether. I don't feel a GFCI is necessary in a shop, unless you do your own wiring without good knowledge of electrical circuits. GFCI's are more commonly used in places where moisture is present, like in a kitchen, laundry or bathroom.

Well the part about GFCT outlets wearing out is correct, but the rest of your statement is a little off base. GFCI outlets don't trip on over current. Also they are required in garages/shops that have concrete floors on grade and it's not because of possible moisture. They are for ground fault protection and standing on a concrete floor makes you a good path for any fault current.


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## LiveEdge (Dec 18, 2013)

I would be careful about advising just removing the GFCI outlet. The circuit may include other parts of the house and it's possible there is a bathroom on the circuit which would require such an outlet. As an example, the GFCI for our powder room is not actually IN the powder room.

Is it possible the saw was tripping because something else on the circuit was also running at the same time? (portable AC unit, etc) You put the saw on another plug which happened to be on another circuit and the problem went away?


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## TheFridge (May 1, 2014)

It was the gfci not the breaker.

Do this, plug in another tool that has a ground. If it trips. Get another grounded tool. If it trips. Bad gfci. I replace them all the time. Over current will kill em over time.

If it's not the gfci then logic states bad saw.

Do not buy a tester. It won't test the gfci under load which is what you need. So just plug in another grounded tool. I do it all the time. Electrician 15 yrs bud.


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## LJD4662 (Sep 29, 2013)

Its very iffy when its going to trip, but once it starts it will trip every GFCI outlet in my garage. I just started the saw on a GFCI outlet and it ran fine with nothing else on the circuit. Yesterday I made it half way through a rip before it tripped. After that it tripped every few seconds. I think the only other thing on the circuit at that time was my cell phone charging.


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## shawnmasterson (Jan 24, 2013)

A side note. If you have #12 wire in the box make sure to get a 20 amp GFCI, not a 15 amp. Personally I don't have them any where that isn't within 3 feet of running water. There are none in the shop. This is a choice and yes I know that if I sell FHA I will have to put them in.


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## TheFridge (May 1, 2014)

Put in 20A gfci where you load will be above 10A or thereabouts. Most gfcis will be on a 20A ckt w #12s, laundry, kitchen, bathrooms require a 20A ckt when house is built.

A 15-20$ replacement gfci will be cheaper than a new motor so I'd suggest trying that 1st.


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## LJD4662 (Sep 29, 2013)

I just got finished rough cutting legs for a table I'm making. Made 8 cuts, it tripped on 4 of them. Each time I unplugged and checked the resistance like Ralph described and my meter isn't measuring any resistance. I will try changing the outlet tomorrow.


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## English (May 10, 2014)

GFCI receptacles are required by National Electric Code for receptacles in Garages. I wouldn't take them out. That saw should only be plugged into a 20 amp circuit due to the in-rush at start-up.


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## bonesbr549 (Jan 1, 2010)

Well I see a lot of good responses here. I've seen your issue before. The only thing I don't see is what is the amp rating of your circuit. If 15A and 15A GFCI, putting a load on it with a TS will trip. When they go bad they trip a lot. I know people use the outlet gfci's because they are cheaper, but with a load they wear out easy. I had one do that, and replaced with a breaker gfci and problem solved. However remember you MUST match the outlet to your wire. If it's only 15A most likely you have 14AWG wiring (builders save a buck on wire) and you cannot use a 20A receptacle. If replacing the outlet does not work, then you have voltage being picked up on your gfci that should not be there. Check your saw. My hunch bad outlet. If you use it a lot in your shop, I'd replace with a breaker gfci. JM2CW


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## dontrushme (Jul 23, 2012)

As *WhyMe* put it "GFCI outlets don't trip on over current." They trip on current differential between the black and white wires.

You said "Its very iffy when its going to trip, but once it starts it will trip every GFCI outlet in my garage." If by this you mean that you tried running he saw in other GFCIs, then the problem is most likely the saw, and not that all the GFCIs are bad.

IMHO your problem is very likely that the insulation (most likely in the motor) is breaking down momentarily, possibly with the vibration of the saw, and goes away when the motor stops. That may be the reason the saw runs OK for random times, some times shorter and some times longer times.

Look over the wiring, from the switch to the motor, especially in the motor.


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## higtron (Jan 26, 2011)

The thing that would concern me is the fact that all the other GFCI's are tripping also is this all one circuit or multiple circuits? If it's all one circuit you should only have one GFCI receptacle at the first receptacle from the panel the rest of the receptacles should just be standard receptacles. If it's multiple circuits you have some serious grounding issues that I would be more concerned with than a table saw kicking a breaker. Good luck it may be time to call an electrican to trouble shoot this situation, electrical fire is a very real danger.


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## MrRon (Jul 9, 2009)

Well the part about GFCT outlets wearing out is correct, but the rest of your statement is a little off base. GFCI outlets don't trip on over current. Also they are required in garages/shops that have concrete floors on grade and it's not because of possible moisture. They are for ground fault protection and standing on a concrete floor makes you a good path for any fault current.

WhyMe, I stand corrected. It is not an over current device. I'm not up on the latest electrical code. The last time I had to conform to the code was 20 years ago when I wired up shop. I had it inspected and passed.


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## TopamaxSurvivor (May 2, 2008)

*my meter isn't measuring any resistance*

You probably will not be able see the problem with most meters. It will take a high quality meter such as a Fluke to reliably see the 24 mega-ohms range. By Ohm's Law, that is about the resistance value a GFCI should start tripping. I have seen this with my Fluke on an intermittent tripping problem before, but do not precisely remember the actual values but believe it to have been about 15 mega-ohms.

The standard value for motor insulation used to be a minimum of 10 mega-ohms before modern electronics and AC speed control. I'm not sure what it is now. Most of those old motors would read infinity with a high voltage mega-ohm meter. Lots of them would break down to the 10 mega-ohm standard after overheating. In my experience, they would be going out of service soon after they reached that value.

I would just try a new GFCI. If it trips, the motor is the problem.


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## RichardHillius (Oct 19, 2013)

Not all GFCI outlets are the same. Look for a heavier duty one meant for garage type applications with power tools. You might spend a few bucks more but it will last much longer.


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