For a given conductor size, which material has the greatest ampacity?

The choice of copper as the material with the greatest ampacity for a given conductor size is grounded in its superior electrical conductivity compared to other materials. Ampacity refers to the maximum amount of electric current a conductor can handle before its temperature rises to unsafe levels, which often leads to potential overheating and failure of the conductor.

Copper has a resistivity of approximately 1.68 x 10^-8 ohm-meters, which is significantly lower than that of aluminum, steel, or bronze. This lower resistivity allows copper conductors to carry more current safely without generating excessive heat, thus providing higher ampacity for the same cross-sectional area.

In contrast, while aluminum is lighter and often more cost-effective, it has higher resistivity and, consequently, lower ampacity than copper for the same size. Steel, on the other hand, is not commonly used for electrical conductors due to its higher resistivity and lower conductivity. Similarly, bronze, being an alloy primarily composed of copper and tin, does not match the conductivity of pure copper.

This understanding of material properties is crucial for electrical system design, ensuring that conductors are appropriately sized and material-selected to handle the expected load safely.