Belt Sander Electrocution

[thestelster]

I keep getting electrocuted when grinding down metal on my belt sander. How do I stop that? It arcs from the metal being sanded down, to the belt guard, and then through me. It also happens when I flip the switch to turn off the machine. I've started to use a stick to turn it off, but don't know how to prevent the other.

 

[David]

There's a short to the frame somewhere. I'd start by unplugging it and opening the switch cover. Look for any wire that's missing insulation or any wire that's making contact with the box or any metal that's not another wire.

 

[Whiskey.Gap.Garage]

If you can’t find a short, take some anti-static spray used on clothing and spray the back of the belt with the machine unplugged.

 

[YotaBota]

What they said.

Is this something new or have you been getting zapped for a while?

 

[thestelster]

What they said.

Is this something new or have you been getting zapped for a while?

Well, I've just started using it for grinding metal a couple months ago. Before, it was only for wood, rubber, or plastic.

 

[YotaBota]

Sounds like static. If you have a test lead with alligator clips, ground the switch body to the motor frame and see if that fixes it. If there is no more getting zapped then run a permanent ground strap in place of the test lead.

 

[thestelster]

Still the same. And then I tried putting the alligator clip on the actual switch toggle, and the shock was even worse.

 

[David]

It definitely sounds like there's a conductor that's contacting the machine frame somehow.

 

[YotaBota]

Is that just turning the machine on without doing any grinding of wood or metal?

 

[thestelster]

It definitely sounds like there's a conductor that's contacting the machine frame somehow.

Ok, I'll go looking inside.

 

[thestelster]

Is that just turning the machine on without doing any grinding of wood or metal?

No issue turning it on. I think maybe after grinding metal, the capacitor of the motor is still holding a charge, so when I go to switch it off, I get zapped. IDK.

 

[David]

No issue turning it on. I think maybe after grinding metal, the capacitor of the motor is still holding a charge, so when I go to switch it off, I get zapped. IDK.

If you can turn it on without getting a shock then a short from the start capacitor is a definite possibility.

 

[thestelster]

Ok, I looked in the switch enclosure. Everything looks good, nothing loose or burnt, everything is tight and I checked the continuity of the ground of the plug to the switch, and it's good there. Now what? Go into the capacitor box?

 

[David]

Yup.

 

[Tom O]

Just curious is that marking from a arc?

 

[PeterT]

I don't know if metallic dust in & around the motor windings can manifest into static or shocks, but might be a good idea to have a peek in there too. Vacuum out or blow it clean. The good thing is, looks like your fan is on the opposite side but check cooling direction & any intake openings. I once made an edge chamfering assembly using a trimmer router but I started to notice some little electrical storms & realized it was possible for metallic swarf to drop in there. Normally the motor is pointing down not up & pushing air out. Sawdust buildup could be troublesome but its not problematically conductive. But it sounds more like a connection or component type issue if I had to guess

 

[thestelster]

I don't know if metallic dust in & around the motor windings can manifest into static or shocks, but might be a good idea to have a peek in there too. Vacuum out or blow it clean. The good thing is, looks like your fan is on the opposite side but check cooling direction & any intake openings. I once made an edge chamfering assembly using a trimmer router but I started to notice some little electrical storms & realized it was possible for metallic swarf to drop in there. Normally the motor is pointing down not up & pushing air out. Sawdust buildup could be troublesome but its not problematically conductive.

Well, I vacuumed everything and was still getting shocked so I grounded myself to the belt sander. Worked perfect, though the alligator clip bites a little hard on my finger (hence the elastics to counter act the forces). Amazon sells an anti-static wrist band for $10.00 which I'll order.

 

[David]

Is there no ground on the power cord?

 

[thestelster]

Just curious is that marking from a arc?
View attachment 62971

No. No arcing that I saw.

 

[thestelster]

Is there no ground on the power cord?

There is. That's what I checked for continuity. Between the prong and the ground in the box. And bent the plug in different directions too. All good there.