# Finally, a logical study of why grounding a PVC dust pipe is "useless"!



## woodnthings (Jan 24, 2009)

This guy works in electronics near explosive environments where he must be cautious to avoid static explosions especially around PVC pipe. That's the same pipe a lot of woodworkers use in their dust collection systems and get persuaded that running a bare wire either inside the pipe or around the outside will effectively "ground" it. This video pretty well "explodes" that myth:


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## difalkner (Nov 27, 2011)

Good info and a good video.


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## TimPa (Jan 27, 2010)

at 11:45 he admits that he ran a wire inside his own pipe, becaue it does remove static inside the pipe. 

agreed, that it is unlikely there will be an explosion in a home shop dc system - from wood dust particles. air laden with other combustables (from finishing, gasoline, etc) would be a different story of course. i was an ESD instructor at a large defense contractor, static is powerful. i respect it. do what you wish...


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## woodnthings (Jan 24, 2009)

TimPa said:


> at 11:45 he admits that he ran a wire inside his own pipe, because it does remove static inside the pipe.
> ........


He also says the "it's almost doing nothing, but if you want to do it go right ahead.... " in so many words.

We still need to differentiate between static shock that is "painful or annoying" and "potential static induced dust explosion"
The Dr. Cole article I posted above clarifies that issue by saying that he has never heard of a static induced "home shop dust explosion"
Read the Summary and Recommendation, second paragraph down:
QUOTE:
_Also, there has never, to my knowledge, been a documented case of an explosion problem with PVC in the home shop or a case of an explosion in a filter bag in a home shop_
Grounding PVC and Other Dust Collection Myths

Now, to your point about using highly sensitive electronics in the same area as the dust collector system, you are totally correct!
Not only would the dust itself be harmful because of heat build up, but any potential or actual static would shock damage the electronic components. I would assume that you have taken all the necessary precautions in this regard and would advise anyone using a CNC router or computerized device to do the same.
For those home shops like mine, where I was getting painful and annoying static shocks anytime I was near my running DC, I fixed the issue with a simple bare copper wire between the blower motor and the separator as I posted above. I have no fear of a static induced dust explosion in my shop after doing all the research I have on this issue. YMMV.


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## Kudzu (Dec 23, 2008)

woodnthings said:


> We still need to differentiate between static shock that is "painful or annoying" and "potential static induced dust explosion"


I see this over and over and people focus on the explosion aspect. But getting shocked is rarely talked about and I don't know anyone that likes static shock. 

Removing that shock is work the trouble to me.


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## TimPa (Jan 27, 2010)

the generation of static electricity and its potential when discharged (ESD) has been studied by engineers for decades now. the possible damage to electronics is real. 

will i keep running a bare copper wire thought my dc pipes/hoses - absolutely
do i think it is helping to preveent the generation and discharge of static electricity - absolutely
needed to prevent an explosion in my home - unlikely
needed to help prevent damage to electronic equipment - absolutely

i am glad you posted that Bill, it may help someone...


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## Jay_L (Oct 16, 2020)

Whether useless or not, the NFPA requires grounding and OSHA will issue a citation for non-compliance.


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## woodnthings (Jan 24, 2009)

Jay_L said:


> Whether useless or not, the NFPA requires grounding and OSHA will issue a citation for non-compliance.


For home shops?!!! 
OSHA has not and never will see the inside of my shop without a search warrant specifically naming the items to be searched for as required in the warrant.


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## BigJim (Sep 2, 2008)

I agree, the only reason I would have a ground wire is to keep from getting shocked, I absolutely hate being shocked. Maybe being hit by lightening when I was a kid has something to do with that.


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## Rick Christopherson (Jun 27, 2016)

woodnthings said:


> The Dr. Cole article I posted above clarifies.....


Rod Cole and I were internet friends back when that article was written. As a matter of fact, he asked me to give the article a technical review before he published it, because the topic was outside of his background. I pointed out several significant mistakes in it, but he decided to publish it anyway. 

I haven't thought about the topic for years, and I don't recall the details of the article. However, I would caution you from using it as a reference for any legitimate arguments. 

The video you posted does sum up the situation pretty well, though.


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## RepairmanJack (Aug 4, 2013)

I've read published articles on this topic (not just web articles and videos) and they all say pretty much the same thing - that this isn't a significant fire risk except in very rare circumstances (BIG industrial shops with very dry conditions, etc.) but that reducing static electricity is a definite plus as it keeps the sawdust from sticking to the inner walls. 
I don't use the stuff (PVC) for various reasons, but I do ground my DC pipes to my electrical ground as this is a basement shop.


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## DrRobert (Apr 27, 2015)

Yesterday I got the crap zapped out of me off the wire in the flex going to my drum sander.

Aluminum blast blasts, too. I had them grounded but for some reason didnt reattach the wires when I made some mods.


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## RepairmanJack (Aug 4, 2013)

Sandor Nagyszalanczy, Dust Control book shows all of his machines grounded along with all of his dust collection ducting. I thought that sounded like overkill, but your post makes me want to re-evaluate my position.


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## woodnthings (Jan 24, 2009)

BigJim said:


> I agree, the only reason I would have a ground wire is to keep from getting shocked, I absolutely hate being shocked. Maybe being hit by lightening when I was a kid has something to do with that.


Yup, that was my reasoning also. I would get the meanest ZAP when I got near the DC and for a few years I put up with it. Then I tried the bare copper wire to connect the separator to the blower/motor and that went away entirely. Thankfully!

I can remember when you rubbed the cats fur then touched the door knob as a kid, you got a pretty good jolt.
I guess it's when the dust particles flow along inside the PVC pipe they charge it or get charged enough to produce the static shock?
I don't know what else it could be.... ? anyone?


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## BigJim (Sep 2, 2008)

I don't know the scientific reason, just know it will knock your jock strap loose. Lol


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## HoytC (Dec 30, 2019)

woodnthings said:


> I guess it's when the dust particles flow along inside the PVC pipe they charge it or get charged enough to produce the static shock?
> I don't know what else it could be.... ? anyone?


Exactly right. That's called the triboelectric effect. The PVC steals an electron from the wood becoming negatively charged and leaving a positive charge on the dust particle. Here's some more information:
https://www.alphalabinc.com/triboelectric-series/
https://www.eesemi.com/tribo_series.htm
Quantifying the triboelectric series - Nature Communications

Also note that a grounded wire wrapped around a duct does not remove the charge. Instead, it becomes charged with an equal and opposite charge. This effectively neutralizes the charge in or on the duct, shielding you from that charge.


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## GCTony (Apr 5, 2018)

Jay_L said:


> Whether useless or not, the NFPA requires grounding and OSHA will issue a citation for non-compliance.


On the NFPA grounding requirement comes into play based on size. I think it's over 5000 cfm's bonding is required.


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## holtzdreher (Jul 20, 2016)

The old argument about static igniting things. With black powder firearms the argument goes on across all the major forums. Run of the mill walk across the carpet in wool socks in winter will not do it. But, there are varying degrees of static all the way up to lightning. I lost the link a while ago, but there was a German study about the number of joules of static at which some materials could be ignited. I was surprised at how low the joules could be to ignite some things. There is a centuries old hand cranked static generator at a museum near here. if highly charged it could burn a tiny hole through a playing card with the spark generated between the large brass globes. The thing was a large glass cabinet with brushes that spun between several large glass circles..


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## Botiory (4 mo ago)

woodnthings said:


> He also says the "it's almost doing nothing, but if you want to do it go right ahead.... " in so many words.
> 
> We still need to differentiate between static shock that is "painful or annoying" and "potential static induced dust explosion"
> The Dr. Cole article I posted above clarifies that issue by saying that he has never heard of a static induced "home shop dust explosion"
> ...


Thanks for a number of tips, I think I need to go through my small workspace and secure myself against static as well.


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