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Discussion Starter · #1 ·
Please my Hitachi C B13F bandsaw randomly will trip a GFI. I have 3 different circuits in the garage & it has tripped all 3. It is entirely random--you can start it & it will trip on the 3rd start, the 5th start, the 10th start etc. Absolutely no pattern. I have eliminated the switch so it's either in the motor circuit or I have sensitive GFI's.

It is ONLY the bandsaw that trips them. Have run TS, Jointer, planer, DP. miter saw and NOTHING will trip.

BS does NOT trip the breaker just the GFI.

The circuit is a 120 v 20 amp. the GFI is rated as 20 amp.

So anyone have a suggestion as to how to troubleshoot this before I SHOOT it & put it out to pasture.

OR should I just try replacing the GFI with a different one/style.

Does any know if GFI's come with a slow blow feature?? probably unlikely scine it would defeat the purpose but I figured I'd ask.

Also I don't know of any electrical motor repair shops down here in God's country-- SC just north of GA

Thanks

smitty
 

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John
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I do not use GFI's in the shop, a lot power tools draw a large load at start up, once it is running it drops back to a normal level.
If code enforcement says you have to have them , some time you can pass if you mark the breaker power tools
 
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Discussion Starter · #3 ·
Take out the GFI ??

So are you saying that the GFI outlet can be swapped out & a normal outlet put in to replace it so long as I mark the breaker in the box "power tools" ???

Probably a question for the building/electrical inspector.

will let everyone know

thks
 

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When I wired my place 30 years ago any plug on an outside wall had to be GFI protected but I don't think ones in a garage had to be. I tried using GFI plugs for outside plugins when I lived in northern Alberta. We needed them to plug vehicle block heaters into during the winter. I had to replace them after about a week because they wouldn't make it through the night without tripping and at -40 you can't have that happen. I don't know what it was that caused them to trip as they did not trip right away when I plugged the block heater plug into them.
 

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At the very least, you can try TEMPORARILY replacing your GFI with a regular outlet and see what happens.
 
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It may be doing exactly what it's supposed to do; reacting to voltage leaking to ground.
Having said that, no way would I be using GFI protection in the shop. Not because it has any really bad side effects but rather that they're a p.i.t.a....and expensive to boot.
Awhile back, the CSA (equivalent to your UL) up here was trying to force arc-fault breakers* down everyone's' throats. Thank G*d that didn't fly! :0


* as I recall they were supposed to be for every cct!!!
https://en.wikipedia.org/wiki/Arc-fault_circuit_interrupter
https://www.familyhandyman.com/elec...-sensitive-arc-fault-circuit-breaker/view-all
 

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My DeWalt compressor does the same thing. Only it always doesn't start when it's supposed to. I can plug it in a different circuit that has nothing else running on it and it usually does the trick. Or if I eliminate the longer extension cord and use a real short one rated for power tools it usually does the trick. I think you're right at the limit voltage wise and electricity isn't always "even". So if you happen to catch it on the low end (or high end) it'll trip the breaker. The electrical experts can correct me or put it in the explanitory lanquage.

Only my opinion, but I thnk you're right on that edge.
 

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My DeWalt compressor does the same thing. Only it always doesn't start when it's supposed to. I can plug it in a different circuit that has nothing else running on it and it usually does the trick. Or if I eliminate the longer extension cord and use a real short one rated for power tools it usually does the trick. I think you're right at the limit voltage wise and electricity isn't always "even". So if you happen to catch it on the low end (or high end) it'll trip the breaker. The electrical experts can correct me or put it in the explanitory lanquage.

Only my opinion, but I think you're right on that edge.
Hey John; when the compressor shuts down it's supposed to release the pressure in the cylinder head. There's a valve on it specifically to do that function. If it doesn't release the compression, the motor has to overcome the back pressure in order to get going. If it doesn't it'll pop the breaker.
I had to replace my valve as it was doing exactly as you described.

Air compressor unloader valve | Air Compressor Guide
 

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Thanx, Dan

I'll have to "investigate" further. Sometimes it starts and other times it doesn't, without a little coaxing.
 

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Rick
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I understand having GFI's in the bathroom , but in the shop I'm not certain what the rules dictate?
I know I'd never have them in my shop . Funny as we've managed to overpopulate this world without them ?
It's getting out of hand , as not in new homes they not only want gfi all over the place , but Arc fault breakers in bedrooms . If you push a light switch to slowely it trips , leaving you in the dark . Things are out of hand imo
 

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it's a sign of issues to come.. eventually you'll experience motor failure...
voltage is leaking back to ground most likely because there is a insulation is breaking down or a capacitor is leaking...
 

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Smitty, is it always at startup? Shutdown? Any pattern or similarity at all? A gfi trips when the current running through it, isn't equal between the line voltage, and the neutral. Do you have a dust collector tied into it with an auto-start? Or an auto start for the receptacle the bandsaw is plugged into? Artie
 

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If its only one machine, then you should have that machine checked out. Even a loose wire can cause nuisance tripping.


What conditions causes unexpected tripping
• Ground current exceeding 6 mA when a load is applied.
• Load neutral is not connected to correct terminals.

Is this machine the heaviest user in your workshop? If not, then again you need to get it checked.
If it is, then you may be right on the threshold of the GFi's sensitivity.

There is a Class A GFCI that trips when a ground fault current exceeds 6 milliamps and there is a Class B GFCI that trips when a ground fault current exceeds 20 milliamps.
The class B should only bu used for swimming pool wiring, but if the machine is checked out OK, then it might be in your interest to get a class B fitted (but dont tell the inspector I said that), as even that is a lot better than no protection at all

Dont run without this protection, electricity doesnt take prisoners.
 

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GFCI is in the garage because it feeds the circuit to the exterior outlets. I think (but have never been told) GFCI in the garage makes more sense than putting it outside where it will get wet. Putting it in the garage will protect the exterior outlets (circuit) without exposing the GFCI to the elements which could cause it to corrode and fail. I haven't heard of any other reason for putting it in the garage (more than 6' from source of water).

If your tool is not the issue...
GFCI that behaves intermittently is could be at the early stage of failure. So before replacing it with a non-protected outlet, you should replace it with a new GFCI. If it still trips like this, try a second new one because sometimes they have mfg defects (I've found two in 10 years).

If the third one still trips and you REALLY want to put a standard outlet in the garage. Best option is to add a new circuit to your breaker box, just for running your big tools. If you are unwilling to do that (or hire it) and you must replace the gfci in the garage with a standard outlet, then you must move the gfci to the first exterior outlet in the circuit. There is likely an outlet by your front door and another by your back door. May be a third by your AC unit outside. One of those gets power before the other ones do, that's where you put the GFCI. Determine which pair come from the garage outlet (hot) and put those in the LINE end of the GFCI. Put the others in the LOAD end of the gfci. If you didn't understand this, then you probably should do a bunch more research or call a licensed electrician. Make sure the GFCI located outside has a new water resistant cover. Obviously, turn the power off at the breaker before doing any of this.
 

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Discussion Starter · #15 ·
Only at startup
with or without the switch involved

this saw has a computer style cord on it that odd ball shaped end sorta like a flat top pyramid but heavier

jumped it with a computer and it still randomly tripped
 

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Discussion Starter · #16 ·
@ everend

I understand about the placement of the gfi in the circuit

all the gfi's are in the garage

one circuit is for a golf cart, one for the cable, & last for the door opener & outside light & circuits

I'm planning on researching the 2 styles as suggested by Bob from Cyprus

and I'm planning on removing the motor to look for saw dust & other goodies
 

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Have 3 CFGIs on the wub panel on a post outside my workshop shed. Had tripping on one of the circuits and discovered the electrician had installed 2 20 amp and one 15 amp CFGI which was the one that constantly blew. The problem stopped when I replaced the 15 with a 20. But in the house, it turned out there was an intermittent short in a lamp that did the same thing. If it's just one machine, I'd suspect a short in the nachine.
 

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The thing that makes me suspicious about it being the mechanics of the compressor (rather than strictly a GFI issue) is that it's a compressor rather than say a TS causing the problem.
As I said earlier, I had exactly the same symptoms on mine...and no GFI breaker/receptacle in the cct.
Unloader valves aren't expensive, just replace it; if the problem doesn't go away, then you have a spare one. :)

Good description of how the problem presents itself here...
The air compressor unloader valve

Shop carefully! As I said, it shouldn't be expensive!!!
https://www.amazon.ca/Compressor-Pr...id=1493649198&sr=8-10&keywords=unloader+valve
 
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