I watched an electrician test for live wires by touching them! Made me cringe. He told me that it was OK as long as he used the back of is hand not the front. I understand the logic but don't think that I will try it.

I am not in the trade myself, but I know several electricicans, one electrical engineer and one high-voltage technican.

The general consensus seems to be that unless you go above 10.000 Volts, no one really cares. They will try not to get into situations where the current would flow through both arms (as the heart is somewhat in between, especially with the large artery that goes to the left arm) and that's about it.

"Still I guess they must know what they're doing; they've not previously been killed ..."

Isn't that a form of selection bias. The ones who electrocute themselves never answer your pleas for help.

But proper statistics bear this out as well.

http://www.statistics.gov.uk/pdfdir/mortsec1107.pdf

The secret it seems is to make sure you don't fall off anything.

http://www.building.co.uk/story.asp?storycode=3039851

The same happens to a lot of software developers and software security.