Replies

1. 
   esch5995 | Jul 19, 2021 07:18am | #1

   Some do run it inside, but I think the reason most of us run it outside is because not only is it easier but it won't disrupt the air flow inside the duct. It only takes the smallest disruption to create a potential choke point where blockages could become a problem. The possibility of a screw causing an air leak is extremely remote and can be made almost impossible if you do as I did, spiral wrap the bare copper wire around the pipe with screws at the joints before wrapping the joint with duct seal tape(the aluminum one not duck tape) if you were to run it inside you eventually need to brig it outside through a hole in the pipe anyway which is much more likely to leak.

1. 
   sed156 | Jul 19, 2021 08:50am | #2

   Good to know. Thank you for the feedback. I appreciate it.

2. 
   DRBWWing | Jul 19, 2021 09:39am | #3

   I don't think there is any benefit or need. But I don't live in a low humidity climate, so I could be wrong.

   Aluminum blast gates can collect a static charge, so you might want to ground them. I simply run a wire to the nearest outlet box (mine are metal surface mount).

3. 
   rob_ss | Jul 19, 2021 05:34pm | #4

   There is no risk of spark formation in PVC ducting.

   It simply does not happen.

   Further, the quantities of dust you would have to be shifting to create an explosive mix are simply not feasible outside a large industrial facility. With 4 inch pipe, you would need to generate about 1lb of fine dust per minute to maintain an explosive mixture.

   As the PVC is an insulator, you also don't get large charge density concentrations building up on it, nor can you ground it effectively, nor will running a wire within make the slightest difference, save possibly reducing the risk of a tingle from touching the outside of the pipe.

   Fires in woodbins do occur, but not for this reason. The prevailing theory is that most of those are caused by metal striking fan impellers leading to hot sparks.

   Basically, static build-up in PVC leading to fires is a massive myth and you are wasting your time grounding it. This excellent piece of work by an appropriately qualified person gives chapter and verse.

   http://store.workshopsupply.com/catalogue/pdf/DC-Myths.pdf

   For what it is worth, I live in a very dry climate and use ungrounded PVC. Even shifting dust off my drum sander (the biggest fine dust creator) for an hour at a time will not generate noticeable static. I get shocks of clothing, but not off piping.

4. 
   user-7630268 | Jul 20, 2021 08:42am | #5

   I'm in total agreement with RobertE and Rob SS. After a few iterations my dust collector is stationary. It has 4 "drops". Except for a few feet of flex hose at each drop, the piping is all 6 inch or 4 inch pvc SDR. In its current form this configuration has been in place for several years with no static electricity issues. By the way there are no grounding wires.