RE: [CAD_CAM_EDM_DRO] Static electricity - WOW

Jeff:
 
If you paid close attention to my post you will see I recommend first a ground line back to the distrubution box and THEN for a backup, mainly to help prevent interference with the electronics, a ground rod near the machine.
 
As far as wood dust exploding being an uban legend, you must not have looked hard enough.  It is not a common everyday occurance but it does occur.  And yes it does occur sometimes from static electricity.  I have been to 2 factories over the 26 years or so I have been in this industry where they were totally destroyed by explosion of wood dust.  One of these, it was determined by the investigators, was caused by a maintenance man repairing a section of the dust collector pipe with PVC.  That section caused a big static buildup and ultimately caused a spark inside the pipe, which melted and the fire spread.
 
You are correct about proper dust collection helping to prevent this type of thing, the key is PROPER dust collection and I am afraid there are a lot of people out there that either don't know how to do this or just don't want to spend the money or time.
 
Stay safe.

Randy Abernathy
CNC and Industrial Machinery
service, repair, installation and
design

4626 Old Stilesboro Rd NW
Acworth, GA 30101
Fax: 770-974-5295
Phone: 678-982-0235
E-mail:
randyabernathy@...

--- On Mon, 2/22/10, Jeffrey T. Birt <birt_j@...> wrote:


From: Jeffrey T. Birt <birt_j@...>
Subject: RE: [CAD_CAM_EDM_DRO] Static electricity - WOW
To: CAD_CAM_EDM_DRO@yahoogroups.com
Date: Monday, February 22, 2010, 7:01 PM


 



>On large industrial machines we often ran a separate ground wire from the machine chassis directly to a grounding rod driven into the ground >thru a hole drilled in the concrete floor of the factory or shop.

Hopefully your bonding this to the main supply ground? Most earth ground driven inside of a factory are next to useless as the ground is too dry to provide a good ground at all.

>Many of the fires in woodworking factories start in the dust collection system from static sparks because of improper grounding or using PVC or >other polymer material in the dust collection tubing.

Urban legend as far as I have ever been able to find out. I have found no documented cases of the cause of a fire at a wood working plant being caused by a static discharge (but I would love to see it.). A grain mill would be much more likely and then it is from having just the right combination of flour dust to air, controlling the dust takes care of most of the problem.

Jeff Birt

Check out – Soigeneris.com…

From: CAD_CAM_EDM_ DRO@yahoogroups. com [mailto:CAD_CAM_EDM_ DRO@yahoogroups. com] On Behalf Of RANDY ABERNATHY
Sent: Monday, February 22, 2010 5:23 PM
To: CAD_CAM_EDM_ DRO@yahoogroups. com
Subject: Re: [CAD_CAM_EDM_ DRO] Static electricity - WOW

YES, the machine should have a ground run with the power line which is also connected to the machine chassis. On large industrial machines we often ran a separate ground wire from the machine chassis directly to a grounding rod driven into the ground thru a hole drilled in the concrete floor of the factory or shop.

Are you using PVC by any chance anywhere between your dust collector unit and the machine? If so, get rid of it and put metal pipe instead. If you are using a small portable dust collector or a shop vacuum with plastic head on it, you probably should ground the hose going to your machine.

One other thing you need to know is that wood dust can ignite and explode from even a small spark. Many of the fires in woodworking factories start in the dust collection system from static sparks because of improper grounding or using PVC or other polymer material in the dust collection tubing.

Hope this helps out.

Randy Abernathy
CNC and Industrial Machinery
service, repair, installation and
design

4626 Old Stilesboro Rd NW
Acworth, GA 30101
Fax: 770-974-5295
Phone: 678-982-0235
E-mail:
randyabernathy@ bellsouth. net <mailto:randyaberna thy%40bellsouth. net>

--- On Mon, 2/22/10, Jack <freshwatermodels@ yahoo.com <mailto:freshwaterm odels%40yahoo. com> > wrote:

From: Jack <freshwatermodels@ yahoo.com <mailto:freshwaterm odels%40yahoo. com> >
Subject: [CAD_CAM_EDM_ DRO] Static electricity - WOW
To: CAD_CAM_EDM_ DRO@yahoogroups. com <mailto:CAD_ CAM_EDM_DRO% 40yahoogroups. com>
Date: Monday, February 22, 2010, 2:32 PM

I guess I have a static electricity problem. While cutting a model boat
stand on my router I was using a dust collector . I was holding the
hose by hand. Something touched something else and both I and my
computer got a jolt of static electricity. Has anyone else run into
this? Cures???

I am assuming I need to ground the router which is aluminum on a wood
stand. Do I need to somehow ground the plastic hose on the dust
collector?

Any suggestions, insight, etc. appreciated! !!!!!!!!! !

jack

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