How much variation of arc voltage is allowed from the stated value?

• A. 5%
• B. 10%
• C. 7%
• D. 12%

Answer: (C)

Arc voltage governs heat input and arc length, so a welding procedure specifies a target voltage and an allowed variation to keep the process stable and the bead consistent. The standard tolerance here is seven percent. That means the actual voltage can deviate by up to ±7% from the stated value. For example, with a stated voltage of 20 V, the acceptable range is roughly 18.6 V to 21.4 V. Staying within this range helps maintain penetration, bead shape, and overall weld quality; going outside it can lead to changes in heat input that cause defects or poor fusion. If you notice the voltage straying beyond this allowance, check and address the power supply, connections, tip wear, and related factors to bring it back within the limit. Other percentages would be tighter or looser than the standard tolerance, which is why seven percent is the best choice.