Under DCEN with thoriated 1/16" tungsten, what is the amperage range?

• A. 20 to 60 Amps
• B. 150 to 250 Amps
• C. 70 to 150 Amps
• D. 5 to 15 Amps

Answer: (C)

With GTAW, the combination of tungsten size and electrode polarity sets the current you can use safely. A 1/16" thoriated tungsten is sized for moderate to high currents, and using DCEN (electrode negative) tends to put more heat into the workpiece and less into the tungsten, so you can run higher currents without overheating the electrode. That config is typically operated in roughly the 70 to 150 amps range. Going much below 70 amps can make the arc unstable and undercut or poor penetration can result; pushing above about 150 amps increases tungsten wear and can cause arc instability or contamination. So, the best fit for this setup is around 70–150 amps.