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View Full Version : Regarding the welder shock thread - question on belt sander



BadDog
07-14-2006, 05:20 PM
I've got 3 belt grinders I use a lot. One of them shocks me periodically when I switch it off. Strangely, it does not ever shock me after just turning it on and back off, but only after some significant “grinding”, particularly involving slack belt work. It’s just a quick “pop” like static electricity and I had assumed it was just static generated from the belt over the platen like a Vandegraff(sp?) generator affair. Then again, that is a guess/assumption and I got to wondering if the might be another more dangerous explanation. If it were a static effect, why never on the others? If an electrical fault, why only periodically after some time? And shouldn't the ground circuit bleed off any static accumulation anyway? Maybe that's the real problem?

Takes only a minute to type this question so why not... :D

Millman
07-14-2006, 05:24 PM
Static electricity, like using a steel blast head on the end of a rubber air hose, tingles a little bit.

JPR
07-14-2006, 05:27 PM
does the belt grinder have a three pong or two prong plug?

Evan
07-14-2006, 05:54 PM
My buffer generates one heck of a charge in winter when it's dry, even when buffing metal parts. It sometimes makes me drop the part. There isn't any easy way to prevent that since the charge is being built up on the person. I suppose I could use a ESD wrist strap though.

Wareagle
07-14-2006, 11:51 PM
Evan, unless your messing with delicate electronics, I'd forget about the ESD wrist strap. Two reasons:

1) I'd hate to get the ground cord wrapped up in a piece of machinery! That'd make for another story for the close calls thread!

2) If you were to get into a stray voltage, you are grounded and will provide a pathway for the current to follow. With out it, you may become energized, but as long as you are insulated, there isn't a pathway; no pathway = no shock!

On the grinder issue, just check out the ground on the equipment, and verify that the ground is good on the outlet. A cheap three light plug tester is sufficient to check that out (as well as polarity).

Optics Curmudgeon
07-15-2006, 12:49 AM
It's a double insulated tool, with no ground wire, I'll bet. Sounds like static to me. Still, the ground strap sounds like a problem on several levels.

Evan
07-15-2006, 01:10 AM
1) I'd hate to get the ground cord wrapped up in a piece of machinery! That'd make for another story for the close calls thread!

Nope. The cord fastens to a carbon filled rubber wrist band with a simple snap. A tug unsnaps it.

2) If you were to get into a stray voltage, you are grounded and will provide a pathway for the current to follow. With out it, you may become energized, but as long as you are insulated, there isn't a pathway; no pathway = no shock!

Nope, not directly grounded. The cord has a ten megohm resistor in it. It's low enough to bleed off static but not low enough to pose a shock hazard. This sort of ESD equipment was provided by Xerox for use around rotating machinery. The problem is remembering to use it and then remembering that you are hooked up.