Question about voltage, lethal current, skin resistance

Yep. I used to work on the electrics on my car without disconnecting the battery because the bolts on the post clamps were often either rounded/corroded or the lead clamp itself was in danger of breaking the next time I had to tighten it down. I replaced starters, solenoids, alternators, voltage regulators and lots of other things. One day I was replacing an alternator and it slipped while I was positioning it (having just connected up the electrics to it, which you can't do once it is mounted in place) and shorted the battery connection to the block. After a trip to the auto parts store to get a another alternator and voltage regular I got "smart" and disconnected the battery at the solenoid so that I didn't have to disturb the post clamp. But when the nut broke free the wrench came in contact with the fender and tried to weld itself in place. I was able to force the wrench away fairly easily without getting burned but it took a small chunk out of both the wrench and the fender. Not one of my better days. But, demonstrating that even a 16-year old can learn, I disconnected the battery at the terminal and proceeded to finish the job without incident. I still run across that wrench from time to time and it serves as a good reminder that shortcuts are often just not worth it. Fortunately, I didn't damage any wires in the loom (too much).