For aluminum wire to match the carrying capacity of copper, how must its size compare?

To match the carrying capacity of copper wire, aluminum wire must be one trade size larger due to the differences in their conductivity. Copper has a higher conductivity rating compared to aluminum, which means that for the same amount of current to be safely carried without overheating, an aluminum wire needs to have a larger cross-sectional area. This is essential because aluminum's lower conductivity results in greater resistance and heat generation at the same current load. Consequently, choosing a larger size compensates for these differences, ensuring that the electrical performance remains safe and efficient. This information is particularly relevant in scenarios involving wire gauge selection for electrical installations, emphasizing the importance of understanding the material properties when planning electrical systems.