Drill leaks electricity to case

Reply to
RoyJ
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Remember - only 20 milliamp will stop a heart.

Likely it is a powder layer (carbon from the brushes) that sprayed from themselves to the case. Carbon resistor that gets lower and lower.

Likely a simple cleanup (inside) will do the trick.

Martin Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder

Ignoramus3408 wrote:

Reply to
Martin H. Eastburn

If the other guy doesn't live nearby, I live in Baltimore and I'd be glad to have it if you can't fi.

Remove NOPSAM to email me. Please let me know if you have posted also.

Reply to
mm

I agree! I can't think of even one time when the smoke got out that the tool in question still worked.

Harold

Reply to
Harold and Susan Vordos

I found just such a problem in a 1/2 horse motor I use for my tool bit grinder. It ran fine, but showed voltage from the housing to ground. Grounding the housing eliminated the problem, but when I dismantled the motor to replace bearings, I found the source a wire that had been crushed between two members. Insulation was intact, but there was a high resistance leak. Taped the crushed portion and the problem went away.

Harold

Reply to
Harold and Susan Vordos

OK, I will keep you in mind. I am cleaning it right now. Lots of carbon dust flew out after I blasted it with compressed air.

i
Reply to
Ignoramus15109

Harold, I had one like that last year, only it was the power wiring to a 460 V. 15 Hp. motor crushed in the motor junction box cover. Luckily, the AB Powerflex 700 VFD was smart enough to instantly trip, so no light show. This was on a new installation.

Pete Keillor

Reply to
Pete Keillor

Sounds right to me. Which leads me to a question:

Is the power cord two-wire, or three-wire? If three wire, there is little danger of shock, as the ground wire will short the leakage path.

If it's two-wire, I would also rewire the drill, changing to a three-wire cord would also change the cord to be three-wire, thus grounding the case. Because carbon dust will re-accumulate.

Joe Gwinn

Reply to
Joseph Gwinn

It was the case. You two are right. After I blew away the dust with my compressor, the drill stopped tripping GFCI. See my separate post FIXED -- THANKS -- drill leaks electricity to case.

It is three wire, but I forgot to check whether there is conductivity between the case and the ground prong. (I hope so, but I want to make sure of that). I will try to do so tonight. I know that the ground wire from the power lead is securely attached to the case, though, so the check will be more of the CYA variety.

I agree 100%. Most likely it is properly grounded, but I will check with an ohmmeter to make sure.

i
Reply to
Ignoramus22178

It couldn't trip a GFCI unless a ground path is available. Assuming YOU weren't the ground path , then it would have to have been a 3-wire cord, or the GFCI would never have tripped.

LLoyd

Reply to
Lloyd E. Sponenburgh

Good point... Still, I feel like I need to cover my ass and double check this, but yes, it is most likely properly grounded. As a drill with metal case, it should be grounded.

i
Reply to
Ignoramus22178

Mine worked after I put the AC input wire back together. I think maybe the color of the smoke is the key. Certain kinds/colors of smoke are more important than others ;-)

Reply to
Leon Fisk

Hi Iggy,

Harbor Freight puts their Router speed control on sale for ~$12.99 pretty regular. I've used this with my 90 deg angle drill successfully (single speed). It also works with my Sears Die Grinder and Milwaukee 4.5 inch Angle Grinder. See:

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It is in the Feb 27 ending date flier right now for the aforementioned price. I don't know how well it will hold up, it isn't very heavy. I can't believe the heatsink inside (I haven't taken it apart yet) is too substantial. This would give you a lot more control on a single speed drill though.

Reply to
Leon Fisk

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Leon, that's an interesting item... But my issue is torque, not speed. What I was saying was, my regular drill has too much torque fgor me anyway, why would I want a drill with even more torque. A good answer to it was that this 450 rpm drill can have an extra long handle screwed in, so that I could handle extra torque. I think that I will keep this drill for now.

As far as this speed control goes, I am not sure how I would benefit from it, personally. It is a very interesting item though.

i
Reply to
Ignoramus22178

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Hi Iggy,

If you decrease the speed with the above said item, you will also be decreasing the torque. IOW you would be able hold the drill and stall it out at some point and not end up looking like a pretzel. Whether or not the speed control would be up to the stalled condition (I think it would) and for how long is an unknown question.

Do you still have those Sears Die Grinders you wrote about awhile back? If so did you ever get around to replacing the bearings or figuring out why they were so noisy? I suspect I have one just like them (bought it new) and it sounds loud too (soon after using it, it is virtually new yet). I always suspected a vibration/harmonic was setting up in mine. I've been meaning to try the speed control on it for longer than just a test and find out if backing off on the RPM a bit gets rid of it. I should have the manual around for it somewhere too...

Reply to
Leon Fisk

OK, I see now. Thanks.

I sold one a while ago (for $52) and kept another.

No, but it is straightforward -- go to sears.com and get the bearings. I just did not get around to it.

I would be greatly interested in your findings actually. I decided that for whatever little use this grinder gets, I can tolerate a bit of noise and vibration.

i
Reply to
Ignoramus22178

I've got to dig it out and pretend it is really a router for a short time and finish a Deadbolt strike plate recess pretty soon. I'll let you know how the speed control works and whether I can quiet it down or not.

Reply to
Leon Fisk

You are wrong, transformer breath! ;-P (PPppbltltlt!!)

The GFCI is comparing the exact amount of power going out on the hot wire and coming back on the white wire, Period. They have two opposing windings on the same current transformer core, and under normal operation the currents 'out' and 'in' cancel themselves out to a sum zero. GFCI's can work on a poorly grounded system on an older house, though it's not the preferred connection.

Let the power leave on the hot wire and NOT come back on the neutral, there is current sensed in the transformer. And if it's over

3ma for a Class A device the electronics trips the protection.

The leaked current does not need to come back on the ground connected to that GFCI. It can ground out to any handy ground source

- a copper water pipe, or a steel stud or structural member tied to ground in the building, or a grounded natural gas line...

-->--

Reply to
Bruce L. Bergman

True.

The return current has to pass through that one white wire (ground) that was associated with the black wire (hot) that shared the GFCI in question. If some current on the black wire bypasses that GFCI by using some other path to the ground in the panel than the associated white wire, pop goes the GFCI.

So, leakage from drill case, through Igor, and to ground via the waterpipes et al, sets up a race condition: Which will pop first, Igor or the GFCI?

This is the reason to have a well-grounded case. The real danger is more often that a 110-volt shock will cause a fall or other accident than direct electrocution.

Joe Gwinn

PS: To take an extreme example, if one puts a resistor from the black on one circuit to the white of another, both GFCI breakers will pop. At least in theory, but I recall that many GFCIs are designed to ignore added current on the white, only reacting when there is more current leaving on the black than is returning via the associated white.

For the electronically-obsessed, this is achieved by means of a synchronous detector rectifying the amplified unbalance signal from the current transformer, the detector feeding a low-pass filter and a threshold detector. The sign of the detector output varies with the direction of the unbalance of leaving and returning currents.

If I recall, ten milliamps will do it, so a 110/0.010= 11,000 ohm resistor capable of at least 110^2/110= 1.1 watts will do, so a 10K

2-watt resistor will do nicely for an experiment.
Reply to
Joseph Gwinn

And, as Dexter would say, "You are STOOOPID!".

Some imbalance must occur between hot and neutral to kick any GFCI... you even stated that. Ok... now read my post again. IF there's no _other_ ground path (like the user, or the drill sitting on a grounded conductive surface) through which part of the current might leak, AND the GFCI is still tripping, then there MUST - HAS TO BE - a ground path somewhere in the cord/wiring.

It's simple to understand that current flowing on the hot - which doesn't have _any_ other path to follow except the neutral - must be matched by current on the neutral. Balanced currents, no trippy the giffy. Short user to case to ground, and THEN you have the very situation a GFCI was designed to protect against.

LLoyd

Reply to
Lloyd E. Sponenburgh

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