Positive or negative ground turns out to be not that important with the stuff available these days. Everything is enclosed in plastic cases so you need to run two wires to it anyway. And, it's so cheap that if it gets wiped out by a voltage spike, replacement is not a problem.
I found this out after developing a totally isolated, clean power 6 volt positive ground to 12 volt negative ground booster unit.
It seems that I should have been chasing 30 year old broads.
