In article , w_tom wrote:
Ioslation transformer must still have the secondary (the 120
volt side) connected back to the building safety ground. If
not, then the appliance will 'float' - can become electrically
hot. If the transformer is properly designed, then either it
has such a connection OR it has a dedicated grounding wire
terminal to make that necessary connection.

No, that's the point of isolation. Because the appliance floats, it can
become "hot" but the leakage current has no reference to the building
ground so if you touch the hot case, no current will flow through you.

Not that a safety ground isn't _still_ a good idea, mind you.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."