E-rex,
I couldn't agree with Francis more.
I ran sound at an outdoor show about 2 years ago where the power was supplied by a generator. I took one look at the generator set up and aside from two broken electrical outlets that were dangling from the panel, there wasn't a ground stake. First thing I said was "Where's the ground stake?", then "Where's the licensed electrician?", and then "No licensed electrician, no show. I ain't risking my friends lives." One guy steps up and says he works with an electrician but when I asked if he was licensed, he said no. Sorry son, working with an electrician don't count. They finally found a licensed electrician and he supervised the connection of the ground stake. (Oh, they tried to do it themselves the first time but connected the cable to the painted part of the generator. Sorry, it has to be connected to bare metal, try again.) Then they found out that their feeder cable would need to run across a drive that was being used for wagon rides so they had to move the generator and ground stake to the side of the road that the stage was on.
A good ground stake and a common AC ground for the back line and sound equipment isn't just nice to have, as far as I'm concerned, it's mandatory.
I also carry a AC line tester to check the receptacles at every show to make sure the ground is good and the hot and neutral are good.
Something like these:
http://www.toolup.com/Test_Equipment/GF ... D=GT-10GFI
http://www.homedepot.com/prel80/HDUS/EN ... 0&MID=9876
Look up Leslie Harvey of Stone the Crows, bad ground + wet feet = dead.
Sorry for the rambling but I gotta passion for safety.
h2OH