"John Grabowski" wrote in
:

It sounds as though your wiring is in complete violation of the
National Electrical Code. #12 wire is rated for 20 amps and should
have a 20 amp circuit breaker protecting it. The three wire plus a
ground rod set up for a detached building is no longer permissible
under the 2008 code. You need the four wires. Using the bare wire in
the cable as a neutral is not allowed. You are seeing current on the
ground rod because you do not have a good neutral connection. The
ground and neutral must be separate at a subpanel. That connection
together is only made at the main panel or the meter. Romex is not
approved to be used underground even though it is in a pipe. You need
to use conductors such as THWN or type UF cable in your PVC pipe. You
are not seeing any current on the ground rod connected to your main
panel (Assuming it is connected properly) because you have a low
resistance neutral conductor to carry the current back to the
transformer.


Well, yes. That all sounds correct. Thanks.