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I have to ground all my power tools that are hooked to the dust collection system now. I am a little foggy as to how I do this.
I read that I can run a copper wire through the plastic tubing and poke it out just as it reaches each machine, and then screw it to the machine for a ground. The other end tied to the dust collector. I am confused because I also have a 50 foot tube (not in use) that I got from Penn state Ind that says " Just ground the wire at either end of the hose to ground your collection system. 50 feet long."
Does this mean that I can simply tie one end into the collector and the entire 50 foot length is grounded?

Thanks

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Lance@LuthiersForum.com

If you want to run a ground wire through the tubing, the only criteria is
that one end of it be connected to a ground somewhere. It could be at a
machine or at the dust collector so long as they are properly grounded. If
you're not sure about the proper grounding of your electrical system (or if
there are any two prong outlets involved) you may want to run a backup
ground to a cold water pipe.

That said, Penn State probably included that recommendation for the
same 1:1,000,000,000,000,000,000 odds that there were actually any
danger that prompts gas stations to post "no cell phone" stickers by thier
pumps. To my knowledge the risk of a dust explosion caused by static
discharge is non-existant and is essentially a myth. I actually think
Mythbusters did a show on this some time back. The static charge that a
piece of plastic tubing is capable of holding before discharge is far far too
small to create a spark that would ignite even the ideal dust/air mixture.

It may however help keep static down enough to reduce dust clinging to
the tubing. The 50-60 feet of PVC I just pulled down from my shop were
a terrible dust magnet. Although I'm not sure how much a ground wire
would have helped, I suppose it can't hurt.

David Collins39037.6871527778

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I have to agree with David about dust explosions caused by static being a myth. In my 20 years of reading every wood working article written, I recall that every time this comes up it is thoroughly debunked.

Having said that, it is still a good idea.

Mostly I like to ground myself, cause I hate shocks.

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"Building guitars looks hard, but it's actually much harder than it looks." Tom Buck

I was taking a tour of the Heritage Guitars factory in K'zoo a few years ago when we had to evacuate the building due to a fire in their dust collection system ductwork. Any number of things could have caused it, I suppose.

I haven't grounded mine yet ... probably should, though.

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James Warwick
J. Warwick Guitars, LLC
http://www.jwarwickguitars.com

My dust collector will pull about 1100-1200 cfm, and the reason I
decided to switch over to metal from plastic is simply a matter of air flow.
It's not the material itself, but the shapes that it is available in. Metal
ductwork made specifically for dust collectors will have smoother and
wider wyes, 90 and 45 degree fittings, and are crimped for the correct
direction of air flow. Standard HVAC fittings are generally crimped the
wrong way for suction, and the PVC fittings will have a rough joint going
either way. Plus even ef you use sewer & drain pipe it gets rediculously
expensive when you get larger than 4".

The most important thing is to remember to turn off and disconnect the
dust collector whenever you decide to cut or sand metal on a tool. I would
have to imagine that sanding a board with nails, screws, etc., would be
among the more common causes of dust collector fires.

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PLEASE! ...don't dismiss the potential for static electricity to become a source of ignition for a fire or explosion.

I am - by profession - a Master Electrician and electrical system designer for an engineering firm doing work for BP on the North Slope. I have been involved with electrical systems most all of my life.

There is a whole classification of hazardous environments that have been identified and are regulated for both for gases (Class 1) and dust (Class 2) to protect against fires and explosions.

THEY WERE WRITTEN FOR A REASON. And they were NOT written because of a preceived potential for an event. They were written because something did happen and they didn't want it to happen again.

Sorry, but I don't think we should ever offer advise to anyone to dismiss a recognized hazard as a myth, based on what we think to be true. Especially if it is a hazard that has been identified by an agency whose very existence was created to protect the public from such hazards.

Not trying to scare anyone - just trying to warn against being our own worst enemy.

Mahogany out. (I like that better than orange)

[EDIT]Clarification - I'm only warning against advising others that it is ok and there is no danger - you should just ignore codes and regulations when it pertains to - well, anything. People will do what people will do - but we should not offer them any justification for ignoring the NAPA or NEC regulations based on our advise or opinions.

Does that make any sense?tony39037.9084027778

I don't think we need to know what causes static electricity, but static charges are present because there is a voltage potential difference between two conductive surfaces that are electrically isolated from one another. The best way to bring the 2 surface to an equal potential is purposely and permanently to bond them to one another with a wire that acts as an equipment grounding jumper. While bonded together there will always be a 0 voltage potential between them. There will be no static charge build up between them.

The wire doesn't have to be large at all. #18 AWG is large enought to discharge static electricity. Each end fo the wire needs to be effectively attached (bonded)to the metal surface of each piece of equipment you want to include in the "circuit". Running the wire through the duct will not add anything the effectiveness of the grounding system - but doesn't take away anything either.

The ground wire can be routed from tool to tool, OR individual ground wires can be routed from each tool (duct) and then all bonded together. Either way the tools need to be all bonded together back to an earth ground. Your cold water pipe is a good earth ground, or even the plate screw of a receptacle will work (as long as the receptacle is grounded to the electrical system's ground). Again the idea is to eliminate voltage potential differences between equipment and bring everything to 0 by bonding the tools together.

I'm sure everyone knew this - but in case someone didn't ... well, this is your basic / down & dirty. Probably more than you wanted to know - so - no more info unless requested.

Bill Pentz has put together a wonderful collection of just about
anything you could want to know about dust collectors. It would
probably take many nights to read through, but it's a good
bookmark to refer to

http://billpentz.com/woodworking/cyclone/Ducting.cfm

There is another page which like so much information on the
web, is not to automatically be taken as absolute fact. This
fellow seems to have his credentials and research in good
order though.

http://mywebpages.comcast.net/rodec/woodworking/articles
/DC_myths.htmlDavid Collins39037.9066666667

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Eschew obfuscation, espouse elucidation.

I edited my earlier post to include the following -

[EDIT]Clarification - I'm only warning against advising others that it is ok and there is no danger - you should just ignore codes and regulations when it pertains to - well, anything. People will do what people will do - but we should not offer them any justification for ignoring the NAPA or NEC regulations based on our advise or opinions.

I'm reposting it, so everyone gets the benefit of my clarification.

Hope it makes sense.

It does make sense Tony. It's not much work to run a strand of wire through
a tube to a ground. I'm sure it's more important when you get in to larger
pipes or over 1500cfm, but even with a 700cfm 4" pipe it could at least offer
peace of mind.

It's easy for me to say something is statistically & vitually impossible, but I
still buy the occasional lotto ticket.

David Collins39037.924837963

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Eschew obfuscation, espouse elucidation.

Put the wire on the outside.A wire on the inside acts just like placque in your arteries. It's just a matter of time until some shreds of fiber get caught and a clot starts to form and it's a real nuisance to dismantle your ductwork to find this offender. Been there, done that!

Dean

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Dean

     A much much greater likelyhood is something that happened to me while grinding dyall phthalate(electrical insulating material commonly seen as that brown hard almost plastic material).

     In grind this material a piece of the jig touched the grinding wheel and sent a shower of sparks into the vaccuum inlet! No real problem immediately!

     People in other parts of the building were smelling smoke, as the exhaust was sent straight up to the cieling and out across the building I couldn't smell it at all. When it was finally found the whole dust tray was a smoldering pile of dust.

     If we hadn't of caught it the whole shop could of burned. This is much more of a likely event and easily blamed on static, though this of course happens if anybody has heard of grain silo expolsions.

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Billy Dean Thomas
Covina, CA

"Multi famam, conscientiam, pauci verentur."
(Many fear their reputation, few their conscience)

Congrats on your 1000th post Todd!

Great Info guys! Thanks for the input.
So Tony, your saying that I can simply daisy chain my tools together? That the wire does not need to run in or out side the tube it self? That would quick and easy, heck my cold water pipe runs right about my cyclone and all my tools, along the same wall.

Needed or not, this seems quite easy.

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Lance@LuthiersForum.com

Lance - Yes, a simple daisy chain would work fine, but it might not be the best design. Any break in the chain will leave the remaining tools on the "tail end" ungrounded. For instance, if you neede to remove a piece of equipment for service, you would need to make sure your grounding conductors are still connected to one another when the equipment has been removed in order to protect the remaining equipment.

The best design (IMO) would be to have individual grounding conductors from your earth ground to each tool, and - ideally - to have all of the earth grounds collected at one location (easy to check the connections from one place). Eliminates the concern about having a break in the chain.

But either method would work.

The NEC requires cold water pipes to be included as part of the grouding electrode system. However, there are some things that have to be done for it to be acceptable for use. (not going there - PM me if you have questions) The biggest issue to check on would be to detemine if there is any PVC water lines that would electrically isolate it from the main coming into the house or from where it is bonded to your electrical system ground.

Another thing - about the duct. The duct - plactic or not - will discharge it's static electricity through any thing that will conduct that charge to anything with an unequal charge. I would assume that somewhere in the system it is connected to metal. Bonding the metal is about the best (maybe only practical) thing you can do to provide a conductive path for the discharge. I agree with Todd - I'm not sure there is an effective way to really ground the duct itself if it is plastic.

I don't believe you will be able to prevent a static charge from being created, but you can design a grounding path for it it remain at a 0 volt potential with everything else.

One last thing - this seems to be over kill just to protect against static electricity. But this isn't just about static electricity. There are other ignition sources, and shock hazards that these systems work to protect against. My final caution - sometimes we can do things thinking we are making it better, when in fact we may be just giving ourselves a false sense of security, or worse yet introducing another hazard.

I can tell some stories.

Then again - maybe something like this is what we need to look at using to help solve the problem:
http://www.amazon.com/exec/obidos/ASIN/B000636P0K/nextag-aut o-20/ref=nosim

(edited is underlined)tony39038.4970717593

Todd, if you use the S&D pipe do you get your fittings from a local
supplier in your area or have them shipped? I'm in the process of moving
my tool room to the other side of my shop and pulled all the 6" S&D, but
haven't scrapped it yet. I was going to switch to metal ductwork mainly
because I thought the wide 90's and wyes were going to be cheaper than
the double 45 fittings (the system I had before was terrible with short 90s
and T's). It seemed like the 6" SDR35 fittings were way too expensive, but
I've been pricing through local distributors.

I'll probably switch to metal in either case anyway, because at 6" and
1100-1200cfm I'm probably pulling enough air to want to err on the safe
side. Plus I have to have my insurance agent by when I'm done with the
remodel and I'm sure the metal ductwork would look better to him.

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Maybe this would make it possible to ground the plastic pipe.?
Just paint it with this stuff.

here