Mark asked about:

>.... There was discussion about
> using capacitive isolation instead of an isolation transformer.

Mark, the techniques that was being discussed did not isolate the cicuit
from teh mains; it simply used a capacitor to drop the applied voltage to a
managable value.  This technique relies on the series capactive reactance of
the capactor, instead of teh turns ratio of the transformer.

The capacitor will *not* give you isolation from the mains, since it is AC
you are conducting, and it passes through the capacitor ... otherwise it
could not work. The transformer provides isolation because the two windings
are physically insulated, and the energy transfer between them happens by
virtue of the coupling the magnetic flux from one winding to the other.

Hope this helps,

.... Gregg