Arc, TIG, and MIG welding is fairly low voltage, like 15 - 30 volts. To start the arc there's a brief high-voltage high-frequency burst, but it's current limited. So it's pretty safe as far as electrocution goes.
I'm a hobby welder (going on 2 years). My inverter stick welder will go to 90 amps on a 120V outlet and up to 180 amps on a 240V outlet. It's not uncommon for engine drive welders (like what you see on trucks) to go up to 250 or 300 amps.
2 things that make welding relatively safe from electrocution are: (1) the steel you're welding on makes a much better path for electricity flow than your body (especially when you're wearing heavy welding gloves), (2) welding in a dry environment (not raining, not standing in water, not drenched in sweat, etc.).
