QUOTE(gedall40 @ Jul 6 2009, 10:12 AM)

High DC voltage is dangerous, but so can the 50 volts used in for example telephone exchanges, since the fuse protecting the battery can allow enough current to flow to kill you with just 50 volts). On no account should current from these sources be discharged to earth using any part of the body, since the current more often than not travels through internal organs and causes irreversible if not fatal damage.
I am a first aider at work, and as part of our training we were told that
all mains electric shocks should go to A&E for an ECG. It's most likely not necessary, but it should be done (but bear in mind I am doing the first aid
at work course so it is the employer covering themselves in this situation).
The reason given is that an electric shock that goes near the heart can set up an out-of-phase heart rhythm. If you take an ECG, there will be a normal tracing, and a less-powerful version of the same tracing slightly out of step - a sort of 'shadow ECG'. This can just fade away naturally with no problems, but the problem is that if while it is 'wearing out', the shadow ECG and normal ECG cancel one another out - one should be an up and the other a down, and you end up with a flat line...no heart beat.
They did tell us that it is very unlikely, and also that if anything were going to happen it would happen within 24 hours, but that if we ever had to deal with a main electric shock -> ECG required.
Actually, knowing our first aid trainers, they've probably told us the right thing to do, but their reasoning could be thoroughly dubious. They once asked us what was in danger if you had an injury to your left-hand side, and we all muttered 'spleen' and the trainer said 'no, your liver' and proceeded to demonstrate where his liver was on the left side of his body...
Of course, my husband got an electric shock at home once, he told me a day or two later, and laughed at me when I said that if he'd told me at the time I'd've said he needed to go to hospital