# Dust Collector System - Grounded??



## mmckee (Sep 20, 2012)

Hi all,

I recently purchased the Harbor Freight 2hp dust collector system and plan to do a fairly stationary hook up with 4" PVC duct work. I was talking to someone today and they mentioned that the system should be grounded as the air and sawdust moving through the PVC will create a fair amount of static and the possibility for sparking will be high. My shop is fairly small (20×20) and it is just me doing recreational stuff in it.

Has anyone else with a dust collection system had an issue with this? Should it be or does it need to be grounded? Do I not need to worry about it? If I do have to ground it how would I go about that? Any insight would be greatly appreciated.


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## wapakfred (Jul 29, 2011)

I grounded my first system and had a problem with it: it was a royal PITA! Don't worry about it, you don't need to do it, and it's a waste of time/money. Did I mention it's a royal PITA? You might have a personal discomfort issue if you get near the ductwork while the system is running, but otherwise there is no danger from fire/explosion.


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## BillWhite (Jul 23, 2007)

My HF unit is not grounded. No probs.
Bill


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## waho6o9 (May 6, 2011)

My dust deputy is grounded using a wire and a
bolt, nut, washer combo.


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## waho6o9 (May 6, 2011)

http://www.cbc.ca/news/canada/british-columbia/story/2012/08/16/bc-sawmill-fire-causes.html


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## ssnvet (Jan 10, 2012)

If it were really necessary to ground a pvc pipe or flex hose DC system, don't you think there would be at least one report out there of a fire that was started in one of the thousands of systems out there that aren't grounded?

IMHO, for small hobby shop use, with DCs 3 HP and under you can better spend your money in a lot of other areas of your shop and get a lot more improved safety bang for your buck, than you will by grounding plastic pipe.

If your a commercial shop, generatign a lot of CFM and a lot of dust, then you should go all metal.

In the link above, the cause of the fire is attributed to an accumulation of very flamable waste… and any commercial facility in a heavily regulated country, almost certainly has an all steel pipe DC system.

We've had multiple fires in our DC piping at work…. and they have always been attributed to insufficient air velocity leaving deposited wood dust in the horizontal pipe runs (16" trunk line half full) and the ignition source has been sparks from cutting lumber with nails in it (which we routinely do).

We finally got a spark detection and fire supression system installed…. $50K for a system bought at a bankruptcy auction and refurbished and installed by the OEM.

Read up an you'll learn that trying to ground an system made out of a material that is an insulator is somewhat of an oxymoron.


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## Kelby (Oct 19, 2011)

Lots of people have debunked this myth. There's never been a documented case of static discharge causing a fire/explosion in a dust collection system. People with much more science background than me have put a lot of material on the web explaining why it doesn't happen.

As someone else posted in a link above, wood dust is highly flammable. However, invariably, the cause of fires is a spark or hot piece of metal that gets sucked into the system because a saw blade hit a nail in the material, not static discharge.

Keep a fire extinguisher handy, and always use a metal detector before you cut your material.


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## DaveMu (Jan 4, 2012)

Not grounded here, no problems.


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## TeamTurpin (Oct 3, 2012)

There is about zero chance of a dust system explosion in a small shop.

That being said, I went ahead and grounded mine. (You guys just have no idea how desperately bad my luck is.) I screwed sheet metal screws into my 4" pvc dust pipe every couple of feet. I then wrapped a heavy guage copper wire around my dust system's frame and then around those embedded screws. Hopefully if static starts to build up in that pipe, it will jump onto that wire and find that fine Oklahoma clay soil.


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## MR_Cole (Jun 1, 2012)

I have pretty much exactly what you described. I do notice the static. I see dust clinging to the outside of the pvc and and sometimes i can feel it although in the few months ive had it, ive had no problems. I also asked my electrician about it and he said as long as there is no dust sitting in the pipes, its not an issue. This means that you shouldn't have duct work thats to big. If your just using 4" with a 1.5 hp DC then you are totally fine.


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## cstrang (Sep 22, 2009)

I'd ground it, if not for the fire hazzard for the dust clinging because of the static alone, why not go all metal? far easier to ground and where I live when I priced my duct work it was cheaper to go tothe hardware store and pick up some metal duct, no need for the heavy gauge spiral industrial stuff. Regular metal duct will work. Just a thought.


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## Johnnn (Sep 21, 2012)

I stand over a shortish piece of soft plastic flex duct when I'm working at the planer. Static builds up from the flow of debris and sometimes it's enough to give me a little surprise zap in the leg. I don't think I'd worry about the fire hazard, but it might do a number on say the electronic speed control on your lathe or other electronics you may have in your shop.


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## DustPipe (Oct 12, 2012)

I work for Dust technology/ Dustpipe.com, and we manufacture and install dust collectors of all sizes. In a commercial shop, PVC is not only not recommended it is Illegal as per NFPA code 664. Now, in 95% of shops running PVC, you might never have a problem, but they CAN start fires. Also, as mentioned, grounding may not adequately relieve this static. We sell metal ducting and flex hose if you should decide to go that route.


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## johnrs (Oct 13, 2012)

The fact that your shop is small negates the need for any static control. Any static buildup will dissipate once the system is shut off. IF you want to ground it though, I would place wire lugs/screw mounts five to ten feet of run. Attach a ground wire to each lug THEN hook it up to a Grounded Plug Repair Kit you only need the Ground prong anyway and simply plug it into the house outlet….presto…..grounded. Oh, and one more thing, a fire CAN start ANYWHERE.


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## mmckee (Sep 20, 2012)

All the insight is a great help, I will try it the way that it is and go from there. Its not like the system will be running for hours at a time and I will not be sending tons of sawdust thru it either at a given time. I hopefully will be done with it next week as i am just waiting for 2 air flow gates to arrive as I decided to add them at every drop. As soon as I get it wrapped up and cleaned up I will post some pictures.


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## pierce85 (May 21, 2011)

Here are two links that explain why the danger of a dust explosion in a small shop due to static electricity is virtually nill. Is it possible? Yes. Is it possible that you could win the PowerBall jackpot three times in a row? Yes.

http://www.thewoodnerd.com/articles/dustExplosion.html
http://home.comcast.net/~rodec/woodworking/articles/DC_myths.h


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## TheDane (May 15, 2008)

If you are using any solid state electronics (computer, TV, EVS tools, etc.), it is foolish not to ground the DC.

The risk of fire is almost negligible, but the risk of damaging electronic components due to electrostatic discharge is pretty high.

Besides, how much does it really cost to hook up a ground wire!

-Gerry


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## pierce85 (May 21, 2011)

Besides, how much does it really cost to hook up a ground wire!

Good point.


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## JJohnston (May 22, 2009)

I would really, really like to know how to stop getting the #$%^ shocked out of me when I'm using my planer. It's a DW735, so it has the dust hookup right there above the outfeed, so I can't avoid getting near the hose and the outfeed table, both of which zap me if I get within an inch or so. I've figured out that if I grit my teeth and touch it on every board, the shocks aren't as bad as when I try not to touch it, and let the charge build up. It sounds as if I should be grounding myself somehow. The planer is on a plywood fliptop cart with rubber or urethane casters, so I imagine it's insulated from everything. I have about 4' of 6" wire-reinforced flex hose connecting to PVC pipe up at the ceiling.


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## TheDane (May 15, 2008)

JJohnston-I assume your planer is on a grounded circuit. This sounds like ESD (electrostatic discharge).

Try attaching a piece of copper wire to bare metal on the planer (if the 4" hose has a metal fitting, try it), then attach the other end to something you know is grounded (e.g. water pipe, conduit, etc.).

Several years ago I leased office space which was carpeted, and had no humidification. In dry weather, the static buildup was so bad it actually killed off some of the computers in the offices. In our server room/computer lab, we installed anti-static mats, had a 'touch strip' by the door and at each control point, and required the techs working in that room to wear bracelets with a wire tethered to the 'touch strips'. The wires on the bracelets had alligator clips so they could move from one workstation or rack to another.

-Gerry


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## JJohnston (May 22, 2009)

I don't have a water pipe or conduit anywhere near; what else could I connect to?


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## Pete_Jud (Feb 15, 2008)

I run 4 inch PVC pipe around the shop for dust collection, and I think that my risk is much lower than winning the lottery. I have read the links Pierce posted, as well as others, and I will not spend the time or bucks to run uninsulated wire through the plastic pipe.


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## TheDane (May 15, 2008)

JJohnston-Anything that is connected to earth ground.

You might check to make sure the power outlet you are plugging into is properly grounded. It is possible the green/bare wire isn't actually connected to anything that is grounded. The green/bare wire in your service outlet should be connected to a ground bar in your breaker box, which in turn should be connected to a ground rod driven into earth. You can visually check this stuff out, but unless you know what you are doing with electricity, it is best to leave to a pro. The equipment to test grounding is not something the average homeowner would have, but it might be worth having a licensed electrician check out.

-Gerry


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## JJohnston (May 22, 2009)

I don't know for certain it's grounded. I'm pretty sure it is; it was installed by a licensed electrician I hired to add circuits in my garage. I do know that I have a ground rod; I saw it in place and connected when the house was being built. Maybe I should just try the obvious first - electrically connect the dust hose to the planer. As it is, they are isolated from each other because they are connected by a PVC fitting.


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## waho6o9 (May 6, 2011)

This might help. Plug into outlet and read the code
to the corresponding lights.


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## JJohnston (May 22, 2009)

In that case, I can be more certain they're properly grounded - the city inspector put one of those in every outlet before he signed off on the work.


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## thebigvise (Jun 17, 2010)

I agree with the camp that static electricity is a nonissue with PVC.


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