"Woodhead" wrote in message
...
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.


I'd have a whole lot more confidence in your method if they didn't put
(insu/iso)lation on conductors to keep them from grounding.

Testing for stray voltage or bad ground is a good idea in the conducting
saw.