Which steps verify correct polarity in GMAW, and what issues arise from incorrect polarity?

• A. Verify power source polarity per manufacturer and ensure electrode lead orientation is correct; incorrect polarity can cause poor fusion, excess spatter, weak welds, or arc instability.
• B. Increase current to maximum without verifying polarity; this guarantees better fusion.
• C. Use a different shielding gas when changing polarity; this improves arc stability regardless of polarity.
• D. Rely on visual inspection after welding to determine polarity; polarity cannot be checked before welding.

Answer: (A)

Polarity determines where most of the heat goes in GMAW and how the arc behaves, so confirming it before welding is essential. To verify, check the power source polarity setting against the electrode lead connection and make sure the electrode lead is on the correct terminal with the work clamp on the opposite side, exactly as the manufacturer specifies. This placement ensures the arc delivers the intended heat distribution for proper fusion and stable operation. When polarity is wrong, heat is not directed properly, leading to poor fusion, more spatter, weaker welds, and an unstable arc that can wander or fluctuate. The other options don’t address verifying the electrical connections before welding, and they either rely on risky practices (cranking current up high) or misapply remedy steps (changing shielding gas or post-weld inspection) rather than ensuring correct polarity from the start.