What is a common cause of arc blow and how can it be mitigated in GMAW?

• A. Magnetic interference or improper grounding; mitigate by repositioning ground clamp, separating control cables, using a stable ground.
• B. High ambient temperatures cause arc blow; mitigate by cooling.
• C. Wire feed rate too high; mitigate by slowing feed.
• D. Incorrect polarity switches.

Answer: (C)

Arc blow happens when magnetic fields around the welding current create forces that push or deflect the arc away from the intended weld joint. In GMAW, a stable, low-impedance return path is essential to keep the arc centered and consistent. The most effective way to mitigate this is to ensure a solid ground reference and minimize magnetic interference from cable layouts. Repositioning the ground clamp so its return path is as close as possible to the weld area reduces the loop area of the current path and lowers stray magnetic fields that can push the arc off target. Keeping control cables away from power cables and grounding everything to a reliable, clean ground point further minimizes coupling that can distort the arc. In short, a proper, close, and stable ground together with clean cable routing reduces arc blow by stabilizing the magnetic environment around the arc. The other factors listed don’t address the magnetic field directly—temperature, wire feed rate, or polarity switches—so they don’t tackle the root cause of arc blow in this context.