Dave wrote:
the idea on 6ga is to have something heavy enough to handle the current of a
power line fault or lightning surge. so yes, use the 6ga. note that as you
bury the wire it will also reduce the total resistance some more, so its not
a total waste to take what you have left over and add it as buried
radials... don't do the tuck them into the grass trick though, trench or
make a good slit for them so they are in contact with solid dirt, the deeper
the better.

In fact I measured the resistance-to-a-ground-rod from a 20-foot
section of buried bare 6AWG stranded wire, and it was in the hundreds
of ohms. My conclusion was that buried radials, while great for a
vertical antenna installation, were pretty crappy as a DC ground. Of
course it's a lot easier to slit the ground (I have random mixed rocks
but ignore them) than to drive down a ground rod - I did several rods
this morning and am pretty sore from the sledgehammer work tonight.

It is no coincidence that the rods are laid out in a radial-type
pattern (at least until I get up to the driveway).

Tim.