a little Help pls, Electrically "HOT" motor case

[VC455]

I have a bench grinder I've been using for years, works great, BUT.
The motor case is electrically HOT.
I've lived with it, but now that I'm getting older... I thoughtful about getting an unexpected & unwanted, DeFib.
I've found that there is continuity between one blade of the plug to case body/ ie cover mounting screw.
Thoughts??

 

[pattenp]

That's not good. There should be no continuity between the case and the hot legs. I'm surprised you have not been shocked from touching the motor.

Edit: Is that a 115V motor? It could be that the leg that has continuity to the case is the neutral which is not good either, but not as bad as a hot leg.

 

[ddawg16]

If your running it off 120vac....then swap legs so that the neutral is on the case.....or toss the motor.

I think it would be worth the effort to find out why one connect is tied to the case. I 'have' seen some older stuff where the case was tied to neutral but used a polarized plug.

 

[VC455]

I have been shocked, and learn fairly quickly to give the motor some room.
Thanks patten and dawg
I hadn't condsidered that it was Neutral continuity to the case and since it is an
UN-Polarized plug... 50/50 chance of pluging in Hot side.
Thanks again, great haveing GJ resources.

BTW, I'll install a polarized plug,
which blade is neutral Wide or Thin? I suppose I could just look in a box to see which is White...
Sorry for such a niave question.

1)... It could be that the leg that has continuity to the case is the neutral which is not good either, but not as bad as a hot leg.
2) .... find out why one connect is tied to the case. I 'have' seen some older stuff where the case was tied to neutral but used a polarized plug.

 

[pattenp]

Wide blade is the neutral. The thing is the neutral shouldn't be contacting the case. You should fix the problem plus add a three prong plug and cord with a ground to the case.

 

[ishiboo]

I have been shocked, and learn fairly quickly to give the motor some room.
Thanks patten and dawg
I hadn't condsidered that it was Neutral continuity to the case and since it is an
UN-Polarized plug... 50/50 chance of pluging in Hot side.
Thanks again, great haveing GJ resources.

BTW, I'll install a polarized plug,
which blade is neutral Wide or Thin? I suppose I could just look in a box to see which is White...
Sorry for such a niave question.

1)... It could be that the leg that has continuity to the case is the neutral which is not good either, but not as bad as a hot leg.
2) .... find out why one connect is tied to the case. I 'have' seen some older stuff where the case was tied to neutral but used a polarized plug.

The smaller blade is hot, the larger blade is neutral.

Definitely swap the two and install a polarized plug... this is similar to how new motors, appliances, etc. are set up - the difference being that they are physically connected to a separate ground, which connects to neutral at the main panel.

With both methods, if the motor shorts hot to the case internally, it would blow the breaker instead of having a hot motor case which could kill you - which you have now

 

[nehog]

I...
BTW, I'll install a polarized plug,
which blade is neutral Wide or Thin? ...

Easy way to remember: "Wide is white" (so w in wide and w in white.)

 

[truckn_r]

I would replace the cord with a three prong cord and plug set up, and some times the leak to ground is slight and will drain, if its shorted it wil trip the breaker.

 

[ishiboo]

I would replace the cord with a three prong cord and plug set up, and some times the leak to ground is slight and will drain, if its shorted it wil trip the breaker.

A two-prong is fine if it's polarized, no need for a 3-prong since the motor neutral and case grounding are not electrically isolated, unless you remove the connection and isolate the case. Then it could be attached to ground.

I don't think you can easily do that with most motors though as they were designed that way, new motors are "double insulated".

 

[VC455]

Thanks everyone, got it.