GFI Tripping - where to start looking?

[JakeKohl]

I have a 20amp outlet circuit in my garage that includes a string of 20amp outlets and one outdoor outlet (with cover and gasket). I've used this circuit quite a bit. Several months ago, the GFI breaker (20amp) flipped while I was using a heat gun on a medium setting. I'll have to look, but I'm pretty sure that heat gun doesn't have a ground prong (it's brand new, though). I had been using this heat gun on this circuit for about four days previously.

My dust collector is on this circuit as well (1.5hp JET) and I recently added a JET wireless remote to it. Once I installed the remote on it (it's just a plug in-line thing that the dust collector plugs into), about 2/3's the time I use the dust collector, the breaker trips after I've turned the dust collector off at the exact moment the motor spools down enough that the centrifugal switch flips back to free standing mode (the motor is almost stopped). When that centrifugal switch clicks, if the breaker is going to flip, it does it at the same instant the centrifugal switch clicks. I've removed the remote switch and it still flips the breaker on roughly the same percentage of stops.

I've swapped the breaker out with another identical 20amp GFI breaker and it does the same thing. Where would you start looking for the problem?

FYI, there are no other devices on this circuit - no garage door openers, refrigerators, etc..

 

[EOC_Jason]

Maybe check all the connections (including ground & neutral) are tight in your box, then check all the plugs in that circuit too for a loose connection?

 

[sands35]

Does it now pop without the remote start? Perhaps something changed coincidentally with the installation of the remote start?

If it's popping on shut down, then it's something wrong with the motor as stated above.

Heat guns can pull a LOT of amps.

aside:

According to a Square D NEMA calculator:

http://www.schneider-electric.us/do...-and-online-tools/nemamotordatacalculator.xls

A 1.5HP motor is right at the limit of your 20 amp breaker.

Re-wire the dust collector to 220VAC so you can not use a GFCI outlet?

 

[Zeke]

How far down the daisy chain is the collector? Can you plug it in directly to the GFCI? Also, good advice on checking each box in the circuit downstream from the GFCI. When you used the heat gun you pulled a lot of amps and any weak connection got weaker.

There is some stuff about 'capacitive coupling' due to the number of downstream outlets and overall length of the wires, but that's over my head.

 

[LS6 Tommy]

Check the outside box to see if it got wet inside. If that's not it, you may be getting a back feed when the motor is "freewheeling", although I can't see how if the "on/off" switch is open. Also, the heat gun may trip a GFCI all by itself. Resistance heaters are notorious for "leakage". They trip GFCIs all the time...

Tommy

 

[JCfreak]

I'd pull that outside gfi and check for water in the box. The plastic covers have been known to funnel water into the box.
Then pull every plug out just enough to check all your wiring. You probably have a neutral (white) touching a ground somewhere along the way. I've seen happen many times. I remove all my personal GFI's after I pass my inspection. They are too problematic..