Welding cable ampacity refers to the maximum amount of electrical current a cable can safely carry before the insulation begins to degrade from heat. This is a crucial factor in making sure that your welding equipment operates efficiently and safely. In most cases, ampacity takes into consideration material of conductor, area of cross-section, insulation type, ambient temperature, duty cycle. Q: What size welding cable do I need for 200 amps? A: For runs up to 30 feet, 2 AWG or 1 AWG is typically sufficient. For longer runs, size up to 1/0 or 2/0 to reduce voltage drop. The two primary sizing systems are: AWG (American Wire Gauge): A U., 2 AWG is thicker than 4 AWG).