There is a possibility that one of the two machines has a faulty ground
connection and you are seeing the connection of an ungrounded
machine to a grounded one. Check to ensure there is zero-5 ohms
resistance between the saw chassis and the shop-vac motor frame
when they are plugged in...... or....There are kits available to
ground plastic 4" hose to discharge static. Guess it could
happen in aluminum pipe too. Wrap a copper ground wire
around the pipe and screw the ends of the wire to the saw and
DC frame.

Jim


"RayV" wrote in message
oups.com...
My hi-tech DC system for my TS consists of a shop-vac connected to a 30
gallon plastic dust bin. The dust bin is then connected to the bottom
of my contractor saw with a flexible aluminum 4" dryer vent. I
normally have the back of the saw closed off with 1/4" plywood and this
system works fairly well.

Yesterday I needed to clean out the inside of the saw, so I unplugged
the saw and turned on the shop vac. I then bent over and pushed the
sawdust into the chute on the bottom of the saw. While I was doing
this everytime my hand partially blocked the hole leading to the dryer
vent it would compress slighty and touch the frame of the saw. That is
where I saw the spark.

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?