What amperage rating will allow you to weld a plate over 3/8 of an inch?

• A. 60-120 amps
• B. 500-700 amps
• C. 210-430 amps
• D. 1000-1200 amps

Answer: (C)

When welding, amperage provides the heat needed for fusion, and thicker plates require more heat than thin ones. For a plate thicker than 3/8 inch, you need a mid-to-high current to achieve proper penetration without burning through. A range around 210 to 430 amps is typical for common welding setups on carbon steel with standard filler metals, giving enough heat to fuse the joint while maintaining control.

Using too little current (like 60–120 amps) would not penetrate adequately on this thickness, resulting in a weak weld. Very high currents (500–700 amps or 1000–1200 amps) tend to be excessive for just over 3/8 inch and can cause burn-through, excessive penetration, and distortion. So the 210–430 amp range best matches the requirement for welding a plate over 3/8 inch.