Gary Tait
DaveC
What are my options to run just a ground back to the panel?
Nehmo
That would be fine, but if you run anything back to the panel, you can
just about as easily run the whole romex.
DaveC
If I understand
the code correctly, a ground isn't considered a current carrier and can be
run outside the house, even buried in the earth (I'm speaking of an insulated
wire, of course).
Nehmo
Under normal circumstances a ground wire doesn't carry current, but it
has to be prepared to do so in the event of say a short from the hot to
the case of an appliance. If the case were grounded, then even if you
were holding the case, you would be outside the circuit and unaffected.
The ground wire bonded to the case would carry the errant current.
If there were no corrosion problems, you *could* burry an uninsulated
ground wire. The ground wire is supposed to be electrically connected to
the real ground, and that is exactly what a ground electrode does.
And a metal water pipe does make a good ground. There are certain
considerations: it should also be bonded to the neutral bus on the main
service panel; there shouldn't be any non-metal fittings between your
connection and the pipe entrance to the house; and there should be a
jumper around the water meter. In other words, it should be electrically
continuous to the ground.
NEC compliance is somewhat different than electrical and practical
reality. I understand NEC 2002 didn't allow water pipes a supplemental
ground connection.
This may confuse more that elucidate, but the issue is discussed here
http://ths.gardenweb.com/forums/load/wiring/msg0715444810937.html
But, of course, you didn't say a water pipe was available.