I spent 33 yrs in the telephone industry working on the lines and outside plant equipment and finally managing the inside and outside equipment departments providing service to our customers. We always used copper instead of aluminum lines for its better conductivity, the power companies switch to aluminum and increase the size of their lines due to cheaper costs of the lines. Copper does conduct both heat and electricity way always better than aluminum is what our design engineers preached when it came to buying lines or components, gold being the best conductor