Morgans wrote:

A GFI senses how much power comes out of the hot wire, and goes back into
the neutral. It does not care if the power is going through the tool, or up
one arm and down the other, and it will still think everything is OK. With
a true separate ground, it would have another path for the juice to go and
trip the GFCI. This still does not address the concern that the ground of
the table saw is carrying current, while all it is supposed to do is trip a
breaker. Juice in the saw frame is bad.

Hmm, Morgans makes a very good point here. While GFCIs are a code
approved way to add a 3 prong outlet to an existing 120V ungrounded
circuit, in this case there is a potential exposure because it is
a 240V circuit with a real 240V appliance attached. Not the same
situation.

Morgans is right.

Bill Ranck
Blacksburg, Va.