🔍 Key Concepts

• American wire size units are based on cross-sectional area, not volume • In U.S. electrical practice, the traditional unit for wire area uses the diameter in mils (thousandths of an inch) • Think about how a round wire’s area is usually described: does it use square units, circular units, or cubic units?

💭 Think About

• First, decide whether area should be measured in square units or cubic units—what does area represent? • For a round wire, is it more natural to describe its size by a unit that relates directly to its diameter, or by standard metric area units? • Look at the options that clearly relate to volume versus those that relate to area, then focus on the traditional American electrical terminology.

✅ Before You Answer

• Eliminate any options that refer to volume (cubic) rather than area • Identify which option is a traditional U.S. electrical engineering term for wire cross-sectional area • Confirm that the correct unit is based on mils (0.001 inch) and is used specifically for round conductors in American wire tables