Just finished installing my VSM a couple weeks ago. I asked the same questions. I found twisted 18 guage wire at a local electronics
store that sold, installed and repaired ham radios. The wire is not "marine grade", but it is a short (less than 10 feet) run that is well protected from vibration/damage/moisture/etc. I installed the shunt and temp sensor next to my house bank negative, and added a new negative bus after the shunt in order to "consolidate" any/all grounds pre-shunt. So battery
negative-shunt-negative bus. I was told that I should use 18 or 16 gauge twisted wire for the shunt (by a marine electronics
store); they recommended manually twisting the wire if I didn't have any pre-twisted. The temp sensor wire...I used 20 guage, and did not twist. So far, all seems to be working flawlessly.
Also, I wired a relay into my NovaKool refrig/freezer system, and now monitor
my "Refrig Status" instead of a bilge pump
. Very nice to know my NovaKool is running 19-22 minutes/hour and cycles on and off, on average, 48 times per 24 hours. Works out to 2 amp/hours x 24 hours = 48 amps out of my 12 volt system. With this info, I have a very clear picture about my solar
needs...my next big project
. Hope this helps.