In arc welding, what must be high enough to overcome the resistance of the gap between the electrode tip and base metal?

• A. Voltage
• B. Amperage
• C. Resistance
• D. Power

Answer: (A)

Strike voltage must be high enough to overcome the gap’s resistance between the electrode tip and the base metal. The air gap behaves like an insulator, so you need a sufficient potential difference to ionize the air and form a conducting arc. If the voltage isn’t high enough, the arc won’t strike, regardless of how much current is available later. Once the arc is established, the current (amperage) controls heat input and the voltage drops to the arc voltage, with power simply being voltage times current. So the key factor that enables starting the arc across the gap is having adequate voltage.