10 Ways to Prevent ARC Welding Injury Arc welding is safe if the unit is properly installed and used. You can receive a shock, however, from the primary (input) voltage if you touch a lead or other electrically "hot" component inside the welder while any part of your body brushes the welder case or other grounded metal. If properly installed and used, the arc welder is very safe. If used improperly, the unit can expose welders to fire, explosion, and retinal burns.