[R-390] Isolation transformer question

[2002tii]

Gene wrote:

>Yes, you lose protection.  The GFI measures a difference in current 
>between hot and neutral.  Hook up the isolation transformer.  You 
>can touch one winding and not get a shock because you being at 
>ground does not complete the circuit.  However, grab both windings 
>and you'll electrocute  yourself.

Sure, but that's not what a GFI prevents.  If you are well insulated 
from ground and grab the hot and neutral sides of a GFI outlet, you 
will get a shock and the GFI won't trip.  But if you grab the hot and 
house ground, the GFI will trip.  With a regular non-GFI outlet, hot 
and ground will give you the same shock that hot and neutral will give you.

With an isolation transformer, you can grab either secondary leg with 
one hand and your house ground with the other, and you won't get a shock.

Best regards,

Don



Disclaimer:  There is always a little leakage curent because the 
transformer insulation is not perfect and because there is some 
interwinding capacitance.  But with a good isolation transformer, 
this should be negligible.  This is where the medical-grade iso 
transformers excel -- they are built with the best insulation and 
have balanced windings to minimize the capacitance.