This link might help with understanding and methodology of the grounding of plastic pipe.
Everyone has to understand a couple of basics; any time you have air flow across a surface, you will build static, moisture (humidity) contributes to the control or generation of static.
With all that being said, I have never seen or heard of any definitive evidence of a fire starting in a hobbyist type wood shop environment, which was caused by a static discharge in a dust collection system. If anyone has such evidence I would like the details for my own edification.
In my opinion (as a safety professional for over 35 years) I do not see it as the huge danger that some folks claim it to be. However, the grounding of ducting, even PVC is not that difficult to do. So why not do it?
Is there a danger? Static can always be an issue in a fine dust environment (look at grain silo explosions). Is it prevalent in a hobbyist wood shop? Probably not.
I think the real issue in not the grounding of ducting to prevent an explosion, but more of preventing a static discharge shock that might result in an unintended reaction by an individual. The use of volatiles near a static source is always a paramount hazard.
I'd be interested in hearing from some EE types, if there are any out there, or anyone familiar with the installation of commercial duct systems, as to what their opinion is on the matter.
I have a couple of quite major issues with that video.
I have been a mechanical engineer in commercial catering installations for 20 years, and part of that job involved earth continuity installing and testing. Admittedly this was in the UK, and I know the USA has some variations of regulations, but even so, nobody can say the UK is backward in safety regs.
The first issue is he is advocating a certain type of wire crimp tool that does not meet safety regulations any where in Europe.
The ratchet crimp as in this pic https://www.google.com.cy/search?q=w...ml%3B450%3B314
is far safer, giving a consistant pressure on each use. the thin model used by the guy will give wildly varying pressures according to who uses it. Arnie would cut the crimp in two, a person with arthritis for instance will make a joint that is not secure, and unsecure joints are a big cause of sparking.
The ratchet crimp will only release when the correct pressure has been applied, even if that means a frail person has to use two hands, or even lean it against the bench, but at least you know every joint is consistantly good.
My main concern is the BARE metal wire he is using. I repeat, BARE metal! he is attempting to stop static sparks by looping BARE metal all across the place? He's not insulating the equipment, he's radiating the static.
If the wire was loaded with static and anything metallic was passed anywhere near that bare wire, he would soon learn about static sparks.
Standard household insulated ground wire should be used everywhere on a small earth continuity circuit. If anyone wants to test its efficiency, use a multitester set to Ohms, and check between any of the connections to a known ground. The power socket ground will be enough. While youre there, test your equipment metal case to the same ground screw. Hell, test everything!
We tested to achieve LESS than 0.2 ohms.
A Quick point here for people not used this kind of test on a multimeter, first put the two leads together and measure the resistance of the machine and leads themselves. Its possible to get a reading of 0.6 or so from the machine depending on quality, and this number can vary every single time you use the tester.
So, when making the real test, you should check the machine EVERY TIME. Then when you test you should see the original number plus no more than another 0.2. So in this example, if you got 0.6 from the tester, and then checked the installation, If you got more than 0.8, that would be bad.
(1 decimal point either way would be regarded as fluctuation on a cheap tester, if you got more than 3 decimal points you should be worried)
If you want to be really anal about it, test between every connection on the run, and the run to ground at both ends.
Again, if your leads arent long enough, you can use extra wire to wrap around the test leads to reach, but you must make the self check again before testing the installation.
If you do not achieve these numbers then my advice is to go over the entire installation checking until you do. Or get a QUALIFIED electrician in, not a mate who has done "a bit of that".
Hope this helps.