I wasnt expecting quite so detailed of a comeback ...lol
However, there is a minor error in your calculation. Conductivity is a volume measurement, not a distance measurement. You have to calculate the effective area of the connection (in all directions) and divide it by the distance. It makes conductivity go up real fast.
I once did a little experiment at work. We were working on a high powered alternator syetem for an MRAP vehicle.
There is a requirement that the truck has to go thru water of a certain depth, and the water might be salt water.
I was curious what would happen if I took no precautions.
I bought a 100 gallon Rubbermaid animal stock tank at tractor supply, and put part of my system in it (minus the alternator). The alternator was outside, running off a big electric motor. I expected the current to all be in the milliamp range so I ran some #22 wire from the alternator to the equipment in the tank and filled the tank with fresh water.
Current was indeed in the milliamp range.
The I dumped a cup of rock salt into the 75 gallons or so of water in the tank.
Within a few seconds, I watched the wire get so hot that the part of the plastic stock tank that it was resting on started to melt.
It was "lots of amps" at only 28 volts.