New sander giving me shocks

[Dennis Jarchow]

I just bought the Bosch dual mode 6" sander. I used it for the first time tonight and I was getting shocks from it when I would touch a screw on the top of the sander. It didn't seem like a continuous shock but more like a really strong static shock; though I didn't hold my finger on the screw to see. At first, I thought this might be static buildup from the sawdust in the hose, but it is happening within seconds of turning it on which would seem to rule out static. Not to mention I can sand for hours with my Festool sander and the same hose and vac and not get a shock. To be fair, my Festool doesn't have any exposed metal anywhere I would normally touch. I saw a review on Amazon from a person with the 5" version of the sander having the same issue and he said the shocks got worse over time.

Does this just sound like a static shock or a real electric problem? Thanks.

[Bill Dufour]

Grounded or double insulated? Some duct tape over the screw will fix the problem. Plug it in and touch the screw, turn it on with your finger on the screw and see if you feel anything.
Of course do this on a dry floor wearing good soled shoes not touching any metal objects.
Bill D

[Dennis Jarchow]

Bill, I assume since it is a two prong plug it is double insulated. I will check it tomorrow and will connect a multi-meter to the screw and the ground on the outlet it is plugged to as well.

[Lee Schierer]

Is the outlet wired correctly? The hot and neutral may be reversed.

[Dennis Jarchow]

I checked the outlet for a reversed neutral and hot. Voltages between hot and ground and neutral to ground were as expected.

Then I measured the voltage between the screw where I was getting the shock and ground. With the sander running but not connected to my vac or anything else, it measures about 30 volts. Even with the sander turned off there is about 5 v at the screw. This doesn't seem right, and I assume explains the shocks I was getting. I already had another one on order from Amazon as the first one came with a cracked dust collection tube. Hopefully that one won't be the same.

[Michael Burnside]

Advice on actual electrical checks is advisable as others have posted. If you run the sander without it touching the work surface it should not shock you. If it does, then that sounds like electrical and I would return it.

However, where do you live? If it is winter and humidity, like it is here, is single digits, you're going to get shocked as the sander builds static. Happens every single winter here. If you have a Festool dust extractor with the anti-static hose you can hold that with a bare hand and it will keep you grounded. Let go while you sand and bzzzzzzz Any other hose will build static and you will get shocked periodically.

For really big sands I have one of those wrist straps that plug into the ground outlet on my workbench that keeps me from getting shocked too, but TBH, I'm usually fine just holding the hose. Besides, a shock once in a while is great as it wakes me from the boredom of sanding

[Tom M King]

Glad you're getting it replaced. Mine doesn't do that.

[Dennis Jarchow]

Glad you're getting it replaced. Mine doesn't do that.

Tom, my replacement from Amazon just showed up and I can also measure 30 volts AC between the screw on top of the sander where you rest your hand and ground. Do you have a multi-meter and could you check yours? Thanks for any help.

[Tom M King]

In ER with my -almost 107 year old Mom. Probably be too tied up for a while.

[Tom M King]

Did you try it on another circuit without an extension cord?

[Bill Dufour]

That screw should be electrically floating not connected to any metal anywhere if the tool is double insulated. Two prong plug, modern tool will be double insulated.
I do not think a static charge will show on ac meters. Measure with dc and report results.
Bill D

[Dennis Jarchow]

Tom,

I am sorry to hear about your mother. I hope she is OK. No worries about getting back to me, you have more important things to worry about.

Yes, I just tried both sanders on a different circuit and no extension cord and I still measure 27v on one sander and 30v on the other when I measure the screw on the top of the sander, as well as the large metal piece above the disk that the side handle screws into.

I also called Bosch and at least the first line customer support seemed concerned and said there shouldn't be any voltage there. They are having tier 2 support call me back.

Thanks again.

[Jim Becker]

It's really weird that you have received two units with the same issue, but if they both came from the same supplier, perhaps it's a "batch"...

If you plug in a typical three prong outlet tester, does it light up correctly? (I know you checked manually but...)

[Dennis Jarchow]

That screw should be electrically floating not connected to any metal anywhere if the tool is double insulated. Two prong plug, modern tool will be double insulated.
I do not think a static charge will show on ac meters. Measure with dc and report results.
Bill D

Bill, I measured again on dc and the reading was in the milivolts. Constant 30v ac is at multiple spots on both sanders when running including the large casting the side handle threads into. I also checked my Festool sander, and my other Bosch orbital and AC readings were in the mv range so were just noise.
Thanks! Dennis

[Tom M King]

Does adjusting the speed control show any change? Waiting game here