Grounding a PVC dust collection system

[BenMinshall]

It is a common misconception that PVC needs to be or even can be grounded. PVC is an insulator, and as such it does not conduct electricity. Wood is also mostly an insulator and does not conduct electricity significantly. That means that no matter how you try by running wires through the pipe or wrapping the pipe in wire or foil, the charge will not flow through the pipe. It is an impossibility of physics to "ground" plastic pipe.

Consider this: the insulation in the power cords of all your power tools is made from thermoset PVC. If PVC was in any way conductive, you would get shocked every time you touched a power cord and the power cord itself would melt down as charge could flow freely between the conductors in the cable. PVC is the material that is specifically intended to prevent movement of charge.

If you want to prevent static shocks, then you need to build the dust collection system out of a conductive material like steel, aluminum or antistatic plastic ducts and ground them properly. Note that antistatic plastic is not off-the-shelf stuff like PVC, ABS, HDPE, etc; it is a specially made material with finely ground carbon powder embedded in the plastic effectively making it a conductive material.

[konkers]

The braided strap provides a lot of surface area for electricity to flow because electrons flow only on the surface of wire. Electrons do not go through the middle of a strand

This is a common misconception about current and skin effect. Skin effect (http://en.wikipedia.org/wiki/Skin_effect) only applies to AC and is proportional to frequency. Since static buildup or discharge is not an alternating current you have no skin effect. Even so, the depth at 60Hz is 8.5mm which makes it a non-issue even at 0000 AWG wire. Skin Effect become a larger issue with high speed interconnects such as HDMI (340 MHz) where the skin depth is 0.00412mm.

[nateswoodworks]

I have never heard of an accident but I wasn't going to take any chances either. When I ran mine I ran a copper wire through the whole thing attaching the leading end to a ground wire. I just bought a 50ft roll of 14/3 wire, took the ground wire out and stripped the insulation off of the others until I had enough to to my whole system. I ran it down each drop until the blast gate. I pulled the copper wire taunt and secured it with hot glue at the ends to hold the wire to the bottom of the horizontal PVC and then went over it as much as I could with silicone to keep it there. I figured if it was attached to the bottom it wouldn't be as apt to catch the sawdust and cause it to plug. It would be better to attach it to the top but since I wanted to run it down my drop tubes as well it would have hung right in the way. I did this something like 8yrs ago and still works as great as the day I put it in.

Nate