ingersoll rand electic impact trips gfi

mark ct · Nov 13, 2007

i recently bought a 1 inch drive ingersoll rand electric impact, trouble is it pops the gfi as soon as ya turn it on. it has a warning sticker on it that says E.M.T surpressed grounding required, could this have something to do with the gfi tripping? i never heard of emt surpressed before

Bridgeport Bill · Nov 13, 2007

I can definatly say the GFCI circuits can be a pain in the neck. I do not know what EMT is either, but it it trips all the time and it is a new tool, it could be a weak GFCI breaker or outlet. You could also get a adapter that will isoulate the ground from the tool cord from the ground on the outlet and it should stop tripping. Warning this will nulify the protection of the GFCI circuit.

Mike C. · Nov 13, 2007

1" impact? Yeesh. What's the current draw? Even on a 20 amp GFCI, that might be too much.

gnorbury · Nov 13, 2007

You could also get a adapter that will isoulate the ground from the tool cord from the ground on the outlet and it should stop tripping.

Not only will it nullify the GFI, but it could potentially kill you if some part of the tool casing becomes live. Just don't do it!

Fundamentally, a GFI works on the principal that there should be equal current flowing in the hot and neutral wires of the load device. Any time there is an imbalance, it indicates there is either fault or leakage current finding its way to ground. Typically US domestic GFIs are rated at 5mA trip current.

Sounds to me like your new tool has some sort of issue which needs to be addressed.

440roadrunner · Nov 13, 2007

Actually, the third wire ground should not have ANY affect at all on a GFI circuit. You just said that it works by sensing the imbalance between neutral and the hot lead.

Bridgeport Bill · Nov 13, 2007

As my first statment was, GFCI's do go bad. If it is old or been tripped, it may need to be replaced. I have found several in the past that were just bad. Any thing that was pluged in would trip it. The adapter is not the best soultion, but has alowed the function of a tool in a pinch. Not sure why though.

mark ct · Nov 13, 2007

it is a tool i bought used, it runs fine and according to a multimeter the case is not live when running, so i dont understand the gfi tripping, as for current draw,i have a 20 amp gfi and the tag on the tool only says it draws 10 amps, any thoughts on what might cause it to trip or where to look inside the tool for a current drain off

Tims · Nov 13, 2007

Bill
The ground could provide a path for current to leak. The adapter would eliminate the path to ground and the leakage may not find another path in order to trip the GFCI. Therefore it would work until the leak found a path.

It is legal to replace a two prong outlet in an older installation with a GFCI receptacle.

Tims · Nov 13, 2007

Mark I would try another receptacle if you have one. As far as finding and detecting the leak it is very small. Only milliamps. I can't remember how many. Would be hard to find.

TedCoffey · Nov 13, 2007

Check to see if the GFI neutral is being shared with any other circuit.
Another possibility is that the hammer contains a filter for brush noise suppression that may be leaking to ground.
As stated above GFI does not use the green ground connection and will still protect user(max of about 5ma through the body) even if it is broken or disconnected from the unit. So an adapter isolating the ground wire will get you around this problem but the brush noise filter(if there is one) will be reduced in effectiveness.

Bill D · Nov 14, 2007

EMT surpressed grounding sounds like EMP pulse. Thius tool warms you that it has special grounding requirements and you wonder why it has issues. I read EMT to mean Electro magnetic transients. In other words it is back a dc motor/generator it backfeeds DC current when coasting down. I suppose the GFCI sees Dc as a unbalanced hot to neutral load and trips out.
I think a isolated ground may be called for with no GFCI.
Bil lD.

JunkyardJ · Nov 14, 2007

The ground wire is getting current flow from the impact (this is supposed to happen). The reason that warning label is there is because the ground disapates the leakage current from the motor. The GFCI sees this as a shock hazzard, as in the ground has become live. If you use an adapter, and don't ground the ground leg of the impact, you'll probably get a shock off the case of the impact. The GFCI won't work with that impact, it's not a fault with either device, they just don't work together. The same thing can happen if you don't ground the case of a 3 phase motor, especially with a VFD. What you may be able to do to make it work is connect the neutral to the case, and unhook the ground lead inside the impact. This can be VERY DANGEROUS, if you plug it into a mis-wired plug after that, the case will be HOT! Which means if you pick up the impact, and touch a ground, you can be KILLED! I don't know if that would even work for sure, if GFCIs really sense an imbalance of hot and neutral, it might still trip. I thought they just sensed if the ground had current flow. The best solution is to get rid of the GFCI if you want to use that impact.

anchorman · Nov 14, 2007

"It is legal to replace a two prong outlet in an older installation with a GFCI receptacle."

That doesn't make it any less foolish to use a piece of machinery that has a safety ground without said safety ground.

by the way, DO NOT attempt to do what JunkardJ mentions with re-wiring the impact hammer/driver. It would be much easier *and safer* to replace the GFCI outlet, with a new one. If that fails to remedy the problem, simply put in a nice old-fashioned grouded receptical, and don't tell anyone. The inspectors get all worked up over GFCI outlets out doors, but then who ever works with power-tools in the rain? or is this outlet in the bathroom?

Tims · Nov 14, 2007

If that fails to remedy the problem, simply put in a nice old-fashioned grouded receptical, and don't tell anyone. The inspectors get all worked up over GFCI outlets out doors, but then who ever works with power-tools in the rain? or is this outlet in the bathroom?

IMO this is more dangerous. The fault that a GFCI would protect you from is more than just rain. It could be moisture from the ground or concrete slab, sweat from you hand, and many other unforeseeable problems.

If the tool is new you should not have this problem. If it is an name brand definitely take it back. From China?

macona · Nov 14, 2007

Tools with high draw can trip GFCIs. I have several tools that will trip a GFCI and there is nothing wrong with them.

Walt @ SGS Inc. · Nov 14, 2007

I have several Dumore grinding motors that want to trip GFI circuits. Sometime a real good cleaning of the brushes and the brush holders as well as the old rubber tip of the pencil cleaning the armature fixes the leak that is causing the problem.
Regards Walt..

mark ct · Nov 18, 2007

well i my curiosity made me have to open up the tool and see what was in there, in a spacer between the handle and the tool, the part which had the warning on the outside about grounding and emt filter, i found inside was a little electric board that said emi filter and the two power leads fed thru it to the motor and it had a small ground wire, i removed all this and hooked it up direct and it works great with a gfi and the only difference is some static comes over the radio that was plugged into the same outlet when i tried it, so problem solved

chuckey · Nov 18, 2007

GFIs work by injecting a current at 1KHz into the live wire and compare it to the return current in the neutral lead. If the current is different, the difference in current could be flowing through you (the 5mA as mentioned) so it trips. Your problem is that the device produces a lot of interference it self so it uses capacitors between live and earth and neutral and earth to get rid off this interference. These capacitors are shorting the GFI current to earth, so it trips. Use it in a GFI free zone and use a RCD, these work with the 60Hz so are 15 times less sensitive to the effects of the capacitors. Or remove the capacitors and wipe out radio reception within 100 yards!
Frank

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