Grounding Wire for Dust Collector
I'm redoing my dust collection system, and running some PVC pipe for the dust collector hose system. When running the grounding wire, should I run it inside the pipe, or outside the pipe. On my old layout using DC hoses I did run it inside the hose, but just wondering if it would still work when run on the outside of the hose/pipes (which is easier to run).
Discharge static where it's being generated
The most respected resources on this forum have always advocated for locating ground wire inside, be it a short run of flex line from machine to a main metal duct branch, or a complete pvc system.
Reason: the dust chips are causing static rubbing along inside of any plastic duct, be it flex hose or pvc.
Discharge of that friction energy should be taking place inside as well, in order to shunt any charge as it is being generated.
When placed on the outside, internal static may not be discharged until it reaches ground at the pickup, very close to your machine, which is where you don't want it. Better to discharge inside the tube than let it build to that entry point.
You may be successfully avoiding comm errors with continuous external ground, but you are not fully mitigating risk of fire, IMHO.
Yes, stringy fibers can catch on that wire. My clear flex tube does so periodically, but I am able to see if a clog is developing and take care of it. Indeed, with pvc, you cannot visually detect this problem.
Optimal solution: Use professional grade spiral metal duct work, and you won't need to run a ground wire inside OR outside, as long as you are grounded at the collector. Further, if you are running a professional shop and your insurance company sees it, you'll likely be asked to remove / replace the pvc or risk non-renewal of your policy.
Exceptions:
1>
Quote:
no static problems since the ground wire, going on 20+ years now.
Okay, hard to argue with that for comm issues, but what of the ever-present risk of fire? Neutralization of static with an internal ground wire is again, one step closer to safety, especially with wood chips and dust.
If I recall correctly, you are milling aluminum more than wood, so your exposure is a bit unusual compared to majority of users running primarily wood chips through those lines.
2>Perhaps your insurance carrier hasn't had any major losses with your type of business category in your region and doesn't feel compelled to inspect. Would hate to be in an argument with the adjuster about an unapproved (or worse, excluded from coverage) method of dust collection after a loss.
Just because they haven't discussed it with you, doesn't mean they're cool with it.
I hate taking dictation from government and insurance companies, but thanks to my insuror's inspection and correction of my finish room practices and electrical systems years ago, I function much more safely, and therefore sleep and breathe better. Never did have a problem prior to their advice,
but it doesn't mean I was not at risk.
At the end of the day, the argument for internal grounding of flex lines connected to spiral metal duct wins for me.
Safety First !
Jeff