# PVC Grounding



## djonesax (Mar 3, 2008)

Hi,

I was going to run metal pipe for my dust collection system but I have all this left over PVC from my previous garage shop. So I think I am just going to re-use the old pipe but want to ground it, which I had not done previously. I watched a youtube.com video where a guy put a small sheet metal screw into each blast gate, and section of pipe and then connect them all with grounding wire on the outside of the pipe/fittings/gates. The screw would poke into the inside of pipe just a hair. I had also heard of people running a wire inside the pipe too though and wondered what was the better way. It seems like wire inside the pipe would cause clogs. Thoughts?

Thanks,

David


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## woodnthings (Jan 24, 2009)

*this is a chicken or egg discussion*

According to Bill Pentz, the duct collector guru, there is no need to ground PVC pipe used in a small shop to prevent dust "explosions" ... never has happened so far... AFAIK. a myth. It has to do with large volumes of dust, the amount of spark, etc. not present in a shop home.

http://www.thewoodnerd.com/articles/dustExplosion.html

My only experience with static on a DC is because the feed hose to the separator above the collection bag/barrel is not an electrical conductor. It is a wire wrapped hose with a clear plastic cover and the wire is not connected at either end to the motor or to the separator. So, to avoid SEVERE static shock, I ran a bare copper wire from the motor base to a screw on the separator... problem solved. :yes:


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## ryan50hrl (Jun 30, 2012)

Agreed. It solves an issue that at best is an annoyance.


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## djonesax (Mar 3, 2008)

Lol, I spent a few years in my other house being slightly concerned about the PVC but its seems it was fine. It did built up a lot of dust on the outside of the pipe but I was never shocked from it.

David


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## TimPa (Jan 27, 2010)

there are many factors that are invovled in dust collector safety. amount of use, size/type of dust, velocity, etc.. if the proper amount and type of dust becomes suspended in the air, it can ignite. the air movement inside the pipe causes friction and allows static to built, which can be enough at times to support a spark. 

pro: a ground wire inside the pipe provides a path for the static electricity to discharge before it gets to spark level. con: the wire give wood chips someting to snag on and possibly cause obstruction. your choice.

not sure if the wire outside is as effective.


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## wericha (Apr 29, 2012)

There is absolutely no reason to worry about grounding pvc dust collection piping in a home shop environment. What little static electricity build up you'll have will not be enough to cause a fire.

Running a wire inside the piping is an even worse idea. I guarantee you will have clogging issues and will be pulling it out in short order.


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## Carvel Loafer (Dec 31, 2011)

Well with all due respect to the woodnerd, and the others that have commented on this topic, there is just something that feels wrong about static and sparks and combustible dust in the same mix. I certainly understand the idea of the absolute ideal conditions to cause ignition and more so an explosion, but it is the same with flammable liquids. They have a flash point where you will have ignition. Now wood dust and flammable vapours are not a fair comparison to each other necessarily, but I still have a tough time with the idea of static build up around all that dust. If there was a way to dissipate the charge it would feel better.

All that said from a guy that doesn't have a dust collector though so take it for what it is, my opinion. :blink:


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## woodnthings (Jan 24, 2009)

*You can have your opinion ...*

In spite of the facts, you are entitled to your opinion. Here's more info that may persuade you:

http://www.rockler.com/how-to/exploding-pvc-dust-collection-ductwork/


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## ryan50hrl (Jun 30, 2012)

Carvel Loafer said:


> Well with all due respect to the woodnerd, and the others that have commented on this topic, there is just something that feels wrong about static and sparks and combustible dust in the same mix.



You need to meet the lower explosive limit which for wood dust is around 40g per cubic meter (excluding red cedar). The ability to get 40 grams of dust per cubic meter would be virtually impossible in a home shop.....


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## Steve Neul (Sep 2, 2011)

I think most of the hysteria comes from lawyers trying to put a disclaimer for every possible mishap that might occur with a dust collector. I worked for a company one time that had an industrial dust collector which emptied into a dumpster outside. It caught fire one day but it wasn't caused by the static electricity, the motor caught fire. The fire stayed isolated in and around the motor and only spread a bit because one worker used a co2 fire extinguisher and it blew the burning dust that had settled on the motor for years.


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