shocking table saw

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If he does what you two suggest, there is a real good chance he'll kill someone.
Note that if he wires the ground to the motor frame on an old enough motor (and 1940's is old enough), he'll quite possibly be connecting the grounded and grounding conductors together at the equipment, which will feed current into the grounding conductor.
The current in the grounding conductor could easily fry his SO while his SO is frying his eggs.
don't do it.
scott
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The motor is probably shot! Replacing a motor on an old saw is no problem at all. Do not chuck the saw, it is probably better than any modern equivalent replacement. Dave
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You have a problem that a ground will just cover up. If you want to keep the saw I would find where the current draw is, and correct the problem. If nothing else replace the motor, rewire the switch and inconnecting wires, then add a three wire cord. Many of those older saws were pretty good units, so it may be worth repairing properly. Greg
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Finally someone with the right approach.
The ground is most likely caused by the insulation in the motor getting old and starting to break down or a loose wire in the on/off button. With the unit unplugged open the on/off switch and see if the wires are in good shape or loose or if some bear wire is exposed. If all looks good in that department then its time to have a good look at the motor. What you will need to do a quick check on the motor is a meter called a megger. This meter will test the motor windings and indicate their condition. Since most people don't have a megger at home you just have to remove the motor from the saw and take in to a local motor repair shop. They can test it in two minutes and tell you if the winding insulation is the cause of the problem. And yes it would be a good idea also to install a three pronged plug on the unit after you get it up and running. If there is a slight ground on the unit in the future the ground wire will protect the operator from getting in the ground loop circuit and getting small ZAPS like you are experiencing now. If there is a bad ground the ground wire you installed will cause the breaker to trip which in turn lets you know that you have a bad electrical problem with you machine. Sorry for the long story but I think this pretty much covers everything. In any event don't through the saw out because of a grounding problem. Resolve the proble and you will most likely get another 30 years out of the little darling.
Bill

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I would find out where the current leakage is. Pull the motor and if you don't have an ohmmeter, take it to a motor repair shop. It may be in the motor, or it could also be in the ancillary wiring. Don't just cover up the problem, find the root cause and get it fixed. No need to toss the saw.                            Mark L.
Troy Hall wrote:

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"Mark L." wrote:

Depending on the age of the saw and where it was made the neutral may be internally connected to the saw's frame through the motor casing (one of the reasons for polarized plugs). With the saw unplugged and the switch off use an ohmmeter to check for continuity from the each of the plugs prongs to the frame of the saw. You should see an infinite ohm reading (open).
-- Jack Novak Buffalo, NY - USA (Remove "SPAM" from email address to reply)
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I would love to test the voltage from the tablesaw, while running, to ground with a voltmeter. How much potential is actually present? The saw frame and construction may be dropping a bit of that voltage from load alone or maybe some complex impedance. And remembering back to some of the old radio days, we used to be able to polarize the radio by turning the plug around going to the outlet. But the old radios still had a voltage present (floating) and would arc badly if they came in contact with a grounded chassis.
Philski
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Thats absolutely correct. Not only that, this is a BELT driven device. 2 belts actually. This creates a known energy field. Is it interacting? Lets face it not too many things were UL rated in the early 40's LOL I will be doing some measurements tomorrow to see what I can see. I should be interesting.
signature Troy & Michelle Hall Cogy Farm Clay Center, Kansas 67432

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Okay this is a good one. First of all, if you were to intentionally break off the ground on your three way plug and plug any new saw in, it may or may not exhibit what you are currently experiencing. As soon as the ground from a machine is removed and the plug is plugged in out of phase you will experience a shock. For those that would like to experiment. Disable your ground and plug in your machine both ways an use a multimeter to measure voltage. What you will see is 56 volts when you are out of phase (measured to ground). This is why the shock you are experiencing doesn't seem like full voltage. DAMHIKT. Didn't want to make this too long.Long story short just put a new wire,with ground on your saw and when you wire the plug onto the wire make sure it is phase.

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Are you talking about North American wiring here?
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You may have a short circuit to the frame. Might need to replace the motor with a new one that has a three wire plug on it. This problem will not get better on its own. This is a dangerous situation. Adding a ground wire to the frame will probably stop the problem by tripping the breaker its plugged in to, but of course that won't solve your problem.

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Well, you've gotten a load of conflicting answers here. My guess is you have bad shop wiring, and the neutral is developing a voltage (which it shouldn't). Connecting a ground wire will probably remove the shock by providing an alternate path for the current (which will result in less voltage being developed across the combined return path of the neutral and the ground). In general running a significant current down the ground wire is a bad idea.
The frame of the saw should not be connected to the neutral, especially if it has a non-polarized plug, but 1940 vintage equipment wasn't particularly strict about that (not to mention it might have been rewired by someone unknowledgable somewhere along the line). So you should probably trace down why that is happening, as well as whether you've got a problem with the shop wiring.
You would be wise to have someone experienced with electricity help troubleshoot this.
John
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Sounds like you have a Van de Graaff generator. Electrons from the belts are released and stored in the metal of your table saw. Probably the best thing to do would be looking for a way to isolate this charge dispersal.

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wrote: <snip>

One response to this, in a different thread, brought up the possibility of static discharge causing the "zap". The OP use of the term "frequently" implies it isn't an "every time" occurrence which reinforces the idea of it being a static discharge rather than a current leak.
To the OP: One way to make a determination on this point is to consider whether it happens each time you touch the saw when the saw is running and whether it will occur twice in quick succession. If so, it is probably current leakage and is, or could develop into, a dangerous situation. Correction requires a repair to either the saw's wiring harness or the internal wiring of the motor. Addition of a ground wire will mask the problem but has the undesirable features mentioned elsewhere in this thread.
If it zaps you once but immediately repeating the contact that yielded the first zap is "zap free", then it is likely a build up of static charge and grounding the frame of the saw will cure the problem. In that case, the source of the static buildup likely to be as stated in the other thread - frictional buildup from the rotating belts, a la Van de Graaff generator.
Tom Veatch Wichita, KS USA
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Tom Veatch wrote:

My thoughts on the shock not occurring all the time is the presumed "neutral" being tied to the saw's frame and depending on how the non polarized plug is connected. Connected one way the saw's frame would be on the neutral side of the motor's windings. Connected the opposite way the frame would be "hot".
-- Jack Novak Buffalo, NY - USA (Remove "SPAM" from email address to reply)
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I do not know if the owner of the saw has many shop tools but I would suggest the purchase of a couple inexpensive items. An outlet fault finder can be purchased for a very few dollars. It is worthwhile to check your whole house and find how many plugs are incorrectly wired. An inexpensive volt-ohmeter would help to determine the origin of the unwanted voltage.
If this diagonstic approach is attractive, we can lay out a set of tests that will isolate the problem. It will probably allow for an inexpensive solution to the problem. It will certainly be instructive.
Dick
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yes I do have those tools as I have experience in home wiring and hold a degree in electronics. Like I said I'll be checking this out and reporting back. Was going to do it today but was having too hard of a time breathing to spend it bending like a pretzel
signature Troy & Michelle Hall Cogy Farm Clay Center, Kansas 67432

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Troy Hall wrote:

[snip]
Nice thread topic name. I smile everytime I see it.
Josie
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To define weither its a static discharge or an actual ground you simply need to take a multi meter, set it to AC volts and stick one probe in the ground part of your wall plug, stick the other probe on any metal part of the table saw. A static charge will disapate almost immediately while a ground will give you a constant reading. If the unit is grounded its not a good idea to try looking for it with just your hands until you get several shocks. Each time you get a shock; that indicates that there is a path for electricity to ground using your body as the conductor, not good.

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I can't believe nobody said this yet:
You have a Taser Saw. :P
BTW: My dad grew up on a farm outside Morganville, and went to Clifton H.S. I spent a lot of time in the Clay Center area as a kid visiting my grandparents.
Good times. Good times. Nothing beats a corn-fed whitetail. <sigh>
-Mike

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