re: Danger of sawdust combustion?

Let me weigh in on this. I was a firefighter for 32 years and have been a woodworker just as long. Dust explosions in a home shop environment are 99.99999% nonexistent, they simply do not happen. Even in industrial settings they are rare. The vast majority of the industrial fires are caused by sparks from malfunctioning equipment, ie seized bearings. Dust collection systems over 5000 cfm do require specific grounding and spark arresting technology as well as suppression systems.

Grounding a home/hobby shop dust collection system is only to alleviate nuisance static electricity that feels uncomfortable. There’s no danger of causing a fire or explosion. Years ago I tried running a bare copper wire through the piping I was using and had far more problems with clogging than any benefit I might have derived. I don’t recommend it.