What is arc blow and how can it be prevented?

• A. Arc blow is wandering arc caused by magnetic fields; fix by proper grounding, adjusting lead placement, and moving the workpiece.
• B. Arc blow is a short circuit caused by moisture; fix by drying surfaces.
• C. Arc blow is a normal arc operation; fix by increasing current.
• D. Arc blow is a heat phenomenon; fix by decreasing current.

Answer: (A)

Arc blow is the wandering of the welding arc caused by magnetic fields around the arc, produced by the welding current and the way the return path is arranged. When these magnetic fields interact with the current in the electrode and workpiece, they push the arc off the joint, leading to poor penetration and inconsistent welds. This isn’t about moisture, a normal arc, or a heat effect—those describe different issues. To prevent arc blow, improve the electrical return path and minimize stray magnetic fields: attach the ground clamp close to the weld joint on the same piece being welded, keep the electrode and work leads short and with minimal loops, ensure a clean, solid ground connection, and position or reconfigure clamps or the workpiece so the current returns don't create large magnetic loops around the weld area. If needed, adjust the setup or polarity and recheck fixture grounding to further balance the fields.