# I think i toasted a Motor ....a little bit...



## joebiplane (Oct 22, 2011)

I needte to add a switch to my polishing buffer ( an older Craftsman 1/3 HB motor) i stink at electric.
The motor had two wires  so i extended the wires to go to a flip light switch .
Seeemed simple to me..  run the two wires to the terminals on the switch and connect the power cord wired to the  same swith terminals...RIGHT ???
apearantly that is not right.  when I flip the switch the motor goes on...This is  a good  thing...   when i flip the switch off the motor locks uu lie a scre driver was shoved into fan blade..  the breake pops and all is then quiet.
i went on line and got direction to how to wire it.   I followed the directions and flipped the switch ( after resetting the panel box breaker  And it fired up and ran like a charm...That is until the shifte position and one of the steel legs bumped a drill press next to it.....parks bolted from that touch point like a loose Positive jumper  cable on a car... i pulled the plug and went back to the drawing board.
I concluded that the un grounded plug that came with the motor wasn't helping. but as i said at the start I stink withe eklectricity and i don't like it and it scares me....
I checked the two wires from the motor with an ohm meterafter disconnecting them from the switch and found they were making a circuit... i checked another motor that I had on hand that was known to work properly  and that motor did not show a complete circuit.

Seems to me that my firt effort caused some damage to the buffer motor causing it to send live juice to all the metal connected to it or that comes into contact with it....
Am I on the right track ?????  is it repairable and can a electricly challanged tinkerer repair it ???
Thanks 
joe


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## Tony Wells (Oct 22, 2011)

Well, let's start at the beginning. Is the switch you have a SPST or DPST? That is, does it have two sets of contacts that are made and broken when switched, or is there only a pair of screws like a normal light switch?

A double pole single throw switch is required for 220 volt circuits, but 110 can be switched OK with a single pole single throw switch. That's the light switch style. If the latter, you would run the incoming neutral wire (supposedly white) straight to the motor from the cord, and the hot (normally black) to the switch and from the other terminal on the switch to the other motor lead. 

DPST has four screws, as in 220 volt work, you have to break both leads, as they are both hot. You do have to pay attention to which leads go under which screws in this case, otherwise you could short directly across the supply. 

Also, make sure you use the green ground all the way through to the frame of the motor. If you think you have burned or shorted the windings of the motor to the chassis, you must not have the ground wire connected, or you would immediately trip a breaker. If you didn't ground it, take a meter reading from some bare spot on the frame and a good, known ground such as another machine, or the known to be grounded green wire from a cord set.


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## joebiplane (Oct 22, 2011)

I used jut a plain simple light  switch, Tony.  The motor only had two wires coming out of it that used to go to a toggle switch in the motor housing ( it was an old sears bench grinder....  been working fine but the toggle was dangerous as i had to lean over the buffing wheels to get to the toggle ( the motor is now on the underside of a  stand and there is a belt drive that runs up to the Arbor that holds the buffing wheeels)
if I put the ohm meter to the two wire   pig tail ,while it is disconnected from any wiring , it shows a complete circuit.  Is that normal ???   the motor is NOT a compacitar start unit it is older than that.
thanks,
Joe


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## Tony Wells (Oct 23, 2011)

If you mean the wires from the motor, then yes, they should show a complete circuit. Exactly how many ohms will vary. If you're using one of those new-fangled DMM's, you should read more than a few ohms. If the circuit was open, infinite resistance, then you'd have a problem with a winding or internal motor connection. You should meter between the motor leads and the motor frame also. There you want infinite resistance, otherwise you have potential on the frame....bad.   

If that all checks out, wire the neutral direct to the motor, and the other motor lead to one side of the switch, and the hot from the cord to the other side of the switch. Don't forget the ground to the frame of the motor, even if you have to put a ring terminal under a mounting screw or something.


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