May 122014
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If you want to get a “vigorous” conversation going in woodworking, it seems you only need bring up SawStop or dust collection.

It is true that in my reading and research I can find no instance whatsoever of a static spark in a small shop dust collection system causing a fire or explosion. Therefore some folks are adamant that static dissipation is unnecessary. Large shops and other “dust-producing” industries, such as milling flour, grain, etc., are a different game completely, and there have been some devastating (documented) accidents caused by static electricity.

Then there is the group that (I think) live in humid warm locales and since they have never been shocked or had their hair stand on end from the static in their dust collection system, project their micro-environmental situation onto all others and assume static electricity is a hoax or myth.

There is a group that knows static is a real issue (they have been zapped, seen dust clinging to the outside of their pipes, or felt the tingle as they walked by their ductwork) and for comfort and/or safety reasons feel that providing a static dissipation system is just “good insurance.” I fall into this camp, by the way. For the $30 or $40 cost, why not?

You can add to that a group of folks who have suffered damage to sensitive electronics (smart phones, cameras, iPads, etc.) by static. They, too, are comfortable with the “better safe than sorry” approach. Then, on a serious note, there are the folks with pacemakers who will not get within 50 feet of an ungrounded dust collection system.

As one level-headed commenter on my YouTube channel posted, “Whether or not to ground your system comes down to personal choice.” If you do choose to ground your system, here are two frequently asked questions and answers about that.

PVC is a non-conductive material, so how can you ground PVC?

You cannot… it is merely “verbal shorthand” to say something like “grounding the PVC.” Technically, we are providing a conductive path to ground for excess electrons that accumulate as a result of wood chips and sawdust repeatedly contacting the walls of the ductwork. Think of it this way: Buildings are not conductive, but we install lightning rods to provide a path to ground. We are, in a sort of imprecise verbal shorthand, “grounding the building.”

I have heard it is a good idea to run the ground wire inside the pipe. Is this true?

A conductive path should be provided for excess electrons both inside and outside the pipe. The system I describe in my recent Popular Woodworking webinar, “Dust Collection Ductwork” accomplishes this without the struggle of trying to install a wire inside the pipe. Anything inside the pipe adds airflow resistance and creates the potential for a clog.

CLICK HERE to read Steve Johnson’s full Dust Collection System FAQ.

  One Response to “Shocked By Your Dust Collection System? By Steve Johnson”

  1. I was looking at your dc videos. A couple of comments

    1. Consider sewer & drain pipe over schedule 40. Thinner, lighter, and cheaper

    2. Ground with aluminum self stick tape instead of wire. You can ground inside and out if you like. Much faster to do.

    You will get better airflow with 90 degree bends if you use 2 45 degree bends with more room between the bends.

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