"RayV" wrote in message
oups.com...

A tiny spark between the leg of the saw and the aluminum vent connected
between the plastic dust bin and the plastice adapter on the saw. In
theory, static can ignite fuel vapors or gases, but wood dust?

Both the shop-vac and TS are plugged into properly wired 3-prong
outlets but this is only really grounding them in case of a motor
failure. Should I somehow ground this DC system or just ignore the
static?


A while back an engineer, MIT I think, wrote an article on the subject for
one of the ww mags (sorry, don't remember which one). He essensially
concluded (supported by formulas & math) that you can't move enough air thru
a 4" pipe with a dust collector (let alone a shopvac) to generate enough
static charge to sustain a spark of sufficient duration to ignite wood dust.
But urban legends die hard. Anyway, the spark you saw is the same as the
one you see when you slide out of your car and touch the key to the door.
And if you touch the door with your finger instead of the key you'll feel
it. If you find that discharge thru your finger annoying, that's about the
only reason to ground non-metalic dust collection pipe. You can ground the
metal dryer pipe if it makes you feel better but you will still be building
static charge in the non-metalic shop vac hose. And I'll bet you never
worried about that when you were using the shopvac for other things.