This is something that has bothered me for quite some time. I bought and installed a great system, the Clear Vue Cyclone CV1800, which does a great job collecting and separating the saw dust from my shop. I didn't want to spend the $$$$ for the metal duct although I know it is a better product but not sure worth that much more so I used the 6" PVC pipe and fittings making sure to use the wyes and long radius ells or 2 - 45 degree ells with a short straight piece between them.
I limited the flex hose to as short as possible and when used as tight as possible (stretched out) same as you would with flex duct in a home HVAC system. This has worked well but I always noticed that the arm hair would raise up anytime I got near a running tool while the DC was on. Lately the wire coil in the flex would sometimes reach out and zap me. The end cut on the flex was pealing back on the hose covering the end...
So after watching a video
on grounding the system, actually more than a few videos, I set out to remedy the problem. At 1st I looked for bare copper wire at Lowe's and ended up with 2 reels of insulated green coated wire 14 gauge. I figured I could strip back the connection points but really wanted twisted bare copper and later found this 18 gauge
wire that I really wanted to use. Smaller gauge but a better choice. The 250' spool was more then enough and proved easier to crimp on the 18 gauge ring terminals. Instead of a ring at each end on each section I doubled the wire ends (2 in each terminal) except for the 1st and last. Hope that makes sense.
I drilled the screw holes where the ground wire attached using screws that just cleared the fittings leaving just the tip inside the pipe and countersunk the holes just enough to have that exposed tip. Take a fitting and scrap piece of pipe to determine this depth. I wrapped the wire around the pipe in maybe 6-8" intervals as I worked down the straight pipe using blue tape every now and then to keep it tight til I made the next connection. Each section that connected to a fitting or another pipe was drilled, countersunk, and screwed with a terminal.
It may have been overkill but the fittings had the two connectors drilled and wired as did both sides of the blast gates. In the case of the flex hose I peeled back the cut end that attached to the PVC pipe or blast gate and used a butt connector crimped to the hose wire and bare copper wire. I went all the way back to the PVC connection on the CV1800 and then ran it down the wall to a near wall outlet and tied into the ground on the outlet. Yes, I am comfortable with electrical wiring as I did a great deal of both line voltage and control wiring in my past HVAC life. In old houses with copper/steel water lines you could easily attach a ground clamp and ground at that point.
After several hours of wiring I ran the planner, the worst offender, and tested the system. Not a hair raised on my arm much less a spark to shock me. I have one run off line going to the band saw that needs tying in that I'll get to this evening and the system will be complete. To test the wiring you can rig you continuity meter to test the full wiring from start to finish to be sure there are no breaks in the wiring.
Note on the main line there is a transition that was installed to clear the door that opened inward. That door has been replaced with an active double door that opens outwards so the transition is no longer needed. I may redo that at some point if it proves to be helpful. The minimum straight line to the cyclone is there now that ensures low turbulence thus it separates the saw dust as expected.