Dust Collection Grounding Wires...WHERE?

[Ted Baca]

I am approaching the final touches on my dust collection system. I am using both flex clear wire-reinforced hose and some 4" PVC. I am concerned about the grounding requirements. I have read where some say wrap the wire around the hose/pipe and make sure all wires are interconnected and grounded at each tool and the DC. Others say run the wire inside. I am curious why instead of wrapping the wire aound the flex hose, why couldn't I use that wire? It is exposed at each gate and I could solder a connector and uses a jumper wire across each gate or connector. What do you WW's do in this case?:confused:

[David Rose]

Ted,

There really aren't any grounding "requirements" for air lines, as far as I know. Do some searches here and you will find lengthy discussions about static electricity in PVC lines. Evidence indicates no safety hazzard without grounding.

If you don't want to be shocked from the static electricity in your lines, try what I did. I did this by accident, then read that it was a fix. I had a few feet of power cord that needed to be taken up for the dust collector. I simply wrapped the excess around the PVC near the collector. I've never had a shock from touching it. I think I have three or four wraps around the pipe (just at the one spot) that seems to cover my 25 feet of line.

I guess the induction must effect it some way.

David


I am approaching the final touches on my dust collection system. I am using both flex clear wire-reinforced hose and some 4" PVC. I am concerned about the grounding requirements. I have read where some say wrap the wire around the hose/pipe and make sure all wires are interconnected and grounded at each tool and the DC. Others say run the wire inside. I am curious why instead of wrapping the wire aound the flex hose, why couldn't I use that wire? It is exposed at each gate and I could solder a connector and uses a jumper wire across each gate or connector. What do you WW's do in this case?:confused:

[Frank Hagan]

You might try looking at Rod Cole's testing on static electricity in PVC ducting in home shops at http://mywebpages.comcast.net/rodec/woodworking/articles/DC_myths.html

Its the only real authoritative thing I've seen on it. I think its much ado about nothing, and he puts several of the myths to rest (such as the danger of explosions in the ducting). In terms of eliminating static electric shocks, which I guess can be pretty large, he says:



If you use PVC the primary issue is to protect yourself from a shock. For this I recommend either a bare grounded wire in the duct, or grounded screws through the pipe spaced every 4 inches. This will reduce the maximum charge build-up by allowing more discharges at lower energies. In a four inch duct, the maximum discharge distance to the bare wire is 4 inches, and the maximum discharge distance to the ground screw is 4.5 inches, so both give approximately equal protection. Because both the wire and screw point have very small radii, they will cause discharges at a much lower charge density than you need for a similar discharge to your finger. The advantage of the screws is that they will not hang up shavings like the wire can. If you are not concerned about receiving shocks, you need not ground the PVC ducts. It is likely that the external ground wire, bare or insulated, or grounded foil wrap is safe in the home shop, but this is problematic if you can generate very large amounts of fine dust.

[Bonnie Campbell]

I'm definitely no expert on electricity or wiring. But when I set up my dust collector I'd wondered the same thing. Why not just connect into the hose wiring (instead of wrapping the whole thing). So finally I did. Where I had plastic connector piping I just ran a piece of copper wire from one hose wire to the next using wire connectors to attach. I haven't had any problem with static on my line or shocks, so I guess it worked. I never worked with much in tools before, so, paranoid as I am about 'power tools', I figured wiring was safer than not.