Steve...

Ah yes the tongue tip taste !! There is something tantalizing (addictive perhaps) about the tongue tip taste for a battery (up to 9volts DC) not so ?

And then there's something thats very off-putting like the shock delivered working older monitors and some TV's and getting a nice belt from the LOPT or finding out from the other side of the room as an apprentice with your mentor laughing at you afterwards about the fact that the chasis of one such monitor was live.
Something so different between a shock from DC and one from AC.

Many years back I heard about an incident at a nearby college where a student had used the tongue tip test on a PC PSU (when they still had live coming to the front power switch)...they lived but couldn't do anything but mutter and waffle for quite a while afterwards !

We were always taught to use things like the right hand rule and have a friend nearby (some lecturer's actually joked about it and said the friend was there to laugh at your stupidity or have them test the circuit first :-))

Dave ...
How does one learn without experimenting ?

Keep well

Kind regards

Dennis