Which statement about open-circuit voltage is accurate?

Which statement about open-circuit voltage is accurate?

• A. It exists only during welding
• B. It exists when the machine is on but the electrode is not in contact with the work
• C. It is zero when the welder is on
• D. It only appears when the arc is established

Answer: (B)

Open-circuit voltage is the voltage available at the welding power source output when no current is flowing—that is, before the arc is struck. When the machine is on but the electrode isn’t touching the work, there’s a potential difference across the gap even though no welding current is flowing. This is the open-circuit voltage, and it’s what helps you start the arc. Once the arc is established and current flows, the voltage drops to the lower arc voltage rather than remaining as open-circuit voltage. So the statement describing the presence of voltage with the machine on but the electrode not in contact with the work is the correct idea. The other options aren’t accurate because open-circuit voltage isn’t zero, isn’t limited to the moment of welding, and isn’t only present after the arc is established.

Open-circuit voltage is the voltage available at the welding power source output when no current is flowing—that is, before the arc is struck. When the machine is on but the electrode isn’t touching the work, there’s a potential difference across the gap even though no welding current is flowing. This is the open-circuit voltage, and it’s what helps you start the arc. Once the arc is established and current flows, the voltage drops to the lower arc voltage rather than remaining as open-circuit voltage. So the statement describing the presence of voltage with the machine on but the electrode not in contact with the work is the correct idea. The other options aren’t accurate because open-circuit voltage isn’t zero, isn’t limited to the moment of welding, and isn’t only present after the arc is established.