simplify the thought process...
every place there is combustible dust static electricity is an issue....
the possibility exists...
choose to blow it off, ignore it, gamble, play chicken (w/ yours and other's) w/ life, limb and propertybelieve ''not me,'' or it's all just rhetoric and if the day ''should'' arrive enjoy the I tol'ja so's... https://www.osha.gov/dsg/combustibledust/index.html https://www.osha.gov/dts/shib/shib073105.html NFPA 652: Standard on Combustible Dusts
A wide variety of materials that can be explosible in dust form exist in many industries. Examples of these materials include: food (e.g., candy, sugar, spice, starch, flour, feed), grain, tobacco, plastics, wood
, paper, pulp, rubber, pesticides, pharmaceuticals, dyes, coal, metals (e.g., aluminum, chromium, iron, magnesium, and zinc). These materials are used in a wide range of industries and processes, such as agriculture, chemical manufacturing, pharmaceutical production, furniture, textiles, fossil fuel power generation, recycling operations, and and metal working and processing which includes additive manufacturing and 3D printing.
It's not that I'm disagreeing with anything you have said, and I agree with "belts and suspenders" in this case. However, The real danger of explosions is evident in commercial operations where the use of the dust systems is a continuous operation. The possibilities of static discharge are probable and possible.
However, in a hobby or small shop operation where continuous operations are unlikely the probabilities of a static event are very low.
I have never, in all of my research, ever come across a documented event in a small workshop that caused a fire or explosion due to static discharge in the ducting. I am not saying that there aren't any but I have never found a credible documented case.
That is why in my first post I asked if anyone who has knowledge of such an event to provide me with the details.
I spent 30 years of a much longer career as Safety Engineer for a large aerospace company. My first assignment was to oversee the construction, testing and operations of a building that had a self contained "Mix Room" and three spray cells.
We sprayed primer on a 27 foot by 100+ foot Aluminum tank and then coated it with a cork based mixture in a heptane slurry.
The mix room is where the slurry was made.
We dealt with Heptane, Toluene, Alcohol, and Methyl Ethyl Ketone in the processes. Needless to say, grounding and static was a big issue, right down to the non-conductive flooring and the use of wrist stats for static.
We never had an incident and thank God we eventually did away with the some of the processes.
My point to the ramble is that I have extensive experience in grounding and the techniques involved. Sonnybob is astute in his observations, but for a hobby shop I just don't see a high level of concern over static in the dust system.
I would, personally ground my own systems, but not for the fear of a static discharge fire and certainly not an explosion, but to keep from getting my fingers zapped.
Bottom line, ground the system, it's not "rocket science", if anything it will keep you from getting zapped when you get near the ducts or machinery.