Aluminum branch circuit conductors should be sized ________ copper.

Aluminum branch circuit conductors should be sized one to two sizes larger than copper conductors to safely carry the same amount of current. This is primarily due to the differences in the conductivity and thermal properties between aluminum and copper. Aluminum has a higher resistivity than copper, meaning it is less efficient at conducting electricity. To compensate for this reduced conductivity, aluminum conductors need to be larger in cross-sectional area compared to copper conductors in order to minimize voltage drop and ensure there is sufficient current-carrying capacity without overheating.

On top of that, aluminum also has a tendency to expand and contract more than copper when exposed to heat, which can result in connection issues if not sized properly. Increasing the size of the aluminum conductor accounts for these factors, ensuring both safe operation and adherence to electrical codes which prioritize safety and efficiency in wiring practices.