Grinder Safety Problem

[cleddy]

I have a old tool post lathe grinder with a 2 prong - cord and plug. I don't use it much so am sure it not wore out from over use. Recently touched the machine and noticed a tingle-shock. On further examination with a meter I have 115-120 volts between the grinder and a known ground. I could have got a real shock under different circumstances but with good shoes got by without a tingle. When reversing the plug the problem goes away so this motor is Polar sensitive. I know this can be fixed with a new 3 conductor cord and proper ground but are old split motors known to have a internal ground where this could be dangerous??? I got a deal on a coffee pot and toaster years ago that had this problem but we learned how to plug it in after a while. Amazing how cheap I was back in the day when money was hard to come by??

 

[Tony in SD]

At the very least I would put a polarized plug on the cord with the neutral connected to the larger pin.

 

[Ray,IN]

At the very least I would put a polarized plug on the cord with the neutral connected to the larger pin.

I agree. Tempting fate can have dire consequences. If the old cord is 2-wires, I'd remove it too and connect a new cord properly.

 

[560Dennis]

Convert grinder to grounded plug and suitable 3 conductive cable as soon as yesterday ,as recommended like suggested above .
Too, have electrical connections verification from electrician.
Verify there’s no issues with motor internal wires also. Old cotton cloth insulation,may have failed ,trying to think about other issues vthat does this .

 

[trackrat]

Had a young man work with me that had no electrical knowledge at all the plug was bad on a little water pump sooo he changed it put a tw0 prong plug on a three-wire cord didn't know what to do with the extra wire so he just put it with one of the others. now me on a job need a pump took that pump off of truck threw it in the ditch plugged it in stepped in the water got lit up almost didn't get out, went and got the right plug fixed it went back to work

 

[Mike(NEOhio)]

I'd bet on an internal short in the motor. Reversing the plug puts the hot side to the switch where it can do its job.

 

[SkipperII]

Linda bought a pole lamp, with a small table halfway up the pole. Had it for several years. The bulb went out, she started to change the bulb, grabbed the top with one hand, and the pole with the other. I saw her body stiffen, and over backward she fell. After she recovered, I took the socket apart, sure enough, wired backward.

 

[cleddy]

Linda bought a pole lamp, with a small table halfway up the pole. Had it for several years. The bulb went out, she started to change the bulb, grabbed the top with one hand, and the pole with the other. I saw her body stiffen, and over backward she fell. After she recovered, I took the socket apart, sure enough, wired backward.

Lamps are are bad that way because you can usally plug them in either way putting power to outside of socket instead of center of bulb. It still should be insulated sufficiently to keep user from getting lit up???

 

[cleddy]

I have a old tool post lathe grinder with a 2 prong - cord and plug. I don't use it much so am sure it not wore out from over use. Recently touched the machine and noticed a tingle-shock. On further examination with a meter I have 115-120 volts between the grinder and a known ground. I could have got a real shock under different circumstances but with good shoes got by without a tingle. When reversing the plug the problem goes away so this motor is Polar sensitive. I know this can be fixed with a new 3 conductor cord and proper ground but are old split motors known to have a internal ground where this could be dangerous??? I got a deal on a coffee pot and toaster years ago that had this problem but we learned how to plug it in after a while. Amazing how cheap I was back in the day when money was hard to come by??

So I put a new 3 conductor grounded cord on the grinder and problem is solved. I did see the black side of the cord went to the motor and not the switch so fixing that further isolates the power. One thing I noticed this grinder is on a old Metal lathe also with a 2 conductor cord and before the repair the Lathe had 1.2 volts between the machine and a known ground either way the cord was plugged. Now with a properly grounded cord it is gone. Does this mean I am constantly using power when this machine is plugged in?

 

[Mike(NEOhio)]

So I put a new 3 conductor grounded cord on the grinder and problem is solved. I did see the black side of the cord went to the motor and not the switch so fixing that further isolates the power. One thing I noticed this grinder is on a old Metal lathe also with a 2 conductor cord and before the repair the Lathe had 1.2 volts between the machine and a known ground either way the cord was plugged. Now with a properly grounded cord it is gone. Does this mean I am constantly using power when this machine is plugged in?

Could be. That's why the hot side is always to the switch.

 

[Tony in SD]

So I put a new 3 conductor grounded cord on the grinder and problem is solved. I did see the black side of the cord went to the motor and not the switch so fixing that further isolates the power. One thing I noticed this grinder is on a old Metal lathe also with a 2 conductor cord and before the repair the Lathe had 1.2 volts between the machine and a known ground either way the cord was plugged. Now with a properly grounded cord it is gone. Does this mean I am constantly using power when this machine is plugged in?

Not knowing everything about the setup, I would be hesitant to give a definitive answer but I am leaning toward yes you are consuming power.