Dual Function breakers have a way to indicate what the last trip was (overcurrent, AFCI, or GFCI). Do you know which one it is ?

What Mfg/model number is your dual function breaker?

 

Have you tried the Miter saw on another circuit?

Try that, to isolate this to the saw or not.

If it trips other breakers, return it and get a replacement saw.

I have bought "NEW" breakers, that were junk.

Someone had been in the BOX store, and swapped their bad breaker for the new one out of the box, and put it back on the shelf.

I did get a new replacement, but it took a hundred questions, and insistence to convince them that I was not trying to cheat them.

It's possible that your breaker is weak, and this saw is pulling juse enough to trip it.

I would try the saw on a different circuit, first.

ED

 

I don't know how to tell what function of the breaker tripped. I did plug it in to an outlet outside and it worked fine. But all my other power tools work just fine on the breaker that the miter saw was tripping

 

Most likely something in the saw is triggering the arc fault detection.

 

This is also the ONLY gfci/afci breaker in my entire house. I only have 1 just plain gfci breaker too and i have not tested the saw on that breaker.

 

Joed ok but what the power cord or the switch? How would i tell?

 

Joed ok but what the power cord or the switch? How would i tell?

If the saw is new, it doesn't matter. Exchange the saw for a good one. You have obviously narrowed it down to the saw and not the breaker. If it is not a new saw, and if it is tripping when plugged in, then I would be checking the cord and/or replacing it.

IF that is the only combo breaker in the house, I would seriously consider changing it to a GFCI breaker.

 

Saw is not new i got it used a year ago. Since i just put in the breaker and now days the gfci/afci breakers are becoming code i will try getting a new cord for the saw and hope that fixes it.

 

And it doesn't trip soon as soon as i plug it in it trips the second i turn on the saw. The second i pull the power switch .

 

Don't have a solution, as I have researched here before, but I have a very similar issue with my Craftsman job site table saw.

On any gfi circuit, mine or job site, it will immediately trip the GFI upon startup... but only just most all the time. Sometimes it will successfully start and run.

It is a pretty old saw, bought new but rode hard. It originally worked fine.

It works fine on a non-gfi circuit. Basically now, I just run an extension cord if necessary to a non-gfi.(I have tested the frame for any leakage to ground, and have found no leakage.)

It must have to do with start-up, but I do not understand motors.

 

Then it could be in the switch. Change breakers. If you have only one combo breaker, you aren't complying with "code" anyway, so it won't matter much.

 

A lot of these machines have brush motors. The brushes sometimes will arc as the unit turns. AFCI detects the arcing signature and trips. I have heard of brand new panel installs on new home builds giving trouble to the contractor working because their saws etc. were constantly tripping the AFCI. I don't know what the solution was.

 

I will replace the power cord if it still trips then i will switch my gfci basement breaker with my gfci/afci garage breaker and see if that does it. But since my router and my table saw both work without tripping the breaker it seems it has to be the miter saw. I will also check my circular saw to see if that trips it. That cord is trashed if it doesn't trip it then it has to be in the miter saw

 

Try the saw in the dark, if you see an arc, then you know that it is arcing, and where.

Then you know where to concentrate your efforts.

ED

 

Ok my afci breaker had the red light by afci when i reset it after tripping. I rried every other tool as well. Circular saw with trashed cord, power drill witj trashed cord, oscillating tool, belt sander, orbital sander , and another power sander, table saw router shop vac jig saw and nothing else brushed or brushless tripped it. I opened the handle and the switch was REALLY dirty. It looks like it will be easy to replace both power cord and switch but could it actually be the motor? If so it would be time for a new saw.

 

Change the breaker !!! You probably have worn brushes in the saw and it is arcing. You really don't need arc fault protection in a shop. GFCI will suffice.

 

Well if it is the brushes then I could replace them. The only brushes i see on the diagram are $5.99 a new breaker is $51.

 

However I don't know how to tell if it is the brushes or the power cord or the switch or what. I turned out the lights and I see no arcing.

 

If it was the power cord or the switch I would expect the saw would cut on off when you were using it.

 

It does the second i turn on the switch the breaker trips.

 

I guess just replace cord and brushes and maybe switch too.

 

I have noticed a smell when cutting harder woods maybe brushes would be place to start.

 

New brushes, $5.99....now new cord, $12.....oh, new motor $125, if you can find one. Labor, priceless. New saw or new breaker. Breaker is cheaper.

 

Chandler if it was the motor i would switch breakers. But you are really being over bearing about the breaker instead of helping come up with a solution .

 

Open it up and disconnect the cord and see if it still pops the breaker, if no the cord is good.
Bypass the trigger and does it pop the breaker when plugged in. If no the trigger is the bad part. If yes change the brushes.

I believe the electric break reverses the power on a stop, I don't know if that is redirected or corrected at the stop function or does it do that on start up. The latter could cause a problem with the breaker.



On new construction jobs we often changed the breaker to one with less functions so we could actually work.

 

I could understand that if ALL my tools did the same thing but it is just the one saw.

 

Not all tools rated at 15 amp are the same. You need to take a look at the starting amps required to start the motor. The motor on your table saw may have require a larger starting amperage than your other tools. Especially if the brushes are all carboned up. And the other tools are brushless or the brushes are new.

You can check the amperage draw with an amp meter if you want to make sure that you are comparing apples to apples.

How old is your table saw? Have you cleaned out the inside of the cabinet? Have you cleaned and maintained the bearings and belts? Is there any slippage if it uses belts? Is the motor full of dust so it can dissipate heat?

There are a lot of reasons why one tool can pop a breaker while others work fine. Just read what people have posted and stop discounting them because they don't fit in your pre-conceived thoughts on what it could be.