The arc length rule of 1.5 times the electrode diameter specifically refers to which component's diameter?

• A. Filler rod diameter
• B. Electrode diameter
• C. Shielding gas line diameter
• D. Torch handle diameter

Answer: (B)

In GTAW, arc length is controlled as a function of the electrode size to keep the arc stable. The rule “1.5 times the electrode diameter” means the gap from the tip of the tungsten electrode to the workpiece should be about one and a half times the electrode’s diameter. This works because the electrode diameter sets how concentrated the heat and current are at the tip, so tying the arc length to that diameter helps maintain a stable arc, good penetration, and clean welds. Other components don’t determine arc length: the filler rod diameter affects only the amount of filler, the shielding gas line diameter matters for gas delivery, and the torch handle size is an ergonomic feature. The electrode diameter is the factor that governs the arc length in this rule.