What amperage is required for 3/8" material?

• A. 100 amps
• B. 188 amps
• C. 250 amps
• D. 300 amps

Answer: (B)

Amperage sets the heat input for the weld. For 3/8" plate, you need enough heat to achieve good fusion without burning through. In common welding charts used for SMAW on mild steel, the setting that matches 3/8" thickness falls in a range around the upper hundreds of amps, and 188 amps sits right in that practical, mid-range spot. It provides a solid arc and proper penetration without excessive heat.

Choosing a much lower value, like 100 amps, would likely underheat the joint and cause weak fusion. A much higher value, such as 250–300 amps, increases the risk of burn-through and distortion on 3/8" steel with typical filler. So the 188-amp setting is the best match among the options.