Ok, some folks seem to need to review current and conductor ampacity.
It's pretty simple - the conductance of aluminum is somewhat poorer than copper, so one needs a slightly larger Aluminum conductor.
Once you have that heavier conductor, the voltagd drop for the same length wire is the same.
So, for example, for a few hundred amps, the voltage drop (which is what it's all about) might be the same with 4 ga copper and 2 ga aluminum. Remember, the only term of relevance is voltage drop, which can be calculated as current*resistance. Aluminum has a higher resistance for a given gauge, so the drop is higher. But that is easily mitigated with a bigger conductor. And since the density of Aluminum is like 1/4 that of Cu, the mass required for equal voltage drop is miniscule.
So my curiosity was more about mechanical longevity of CCA. The current carrying capability of Al vs Cu and how to engineer around it is well known.
Of course for the same price, and/or where the value lies, if Cu is a better value, great, but Al is still half or less than Cu on a conductor cost basis.
It's pretty simple - the conductance of aluminum is somewhat poorer than copper, so one needs a slightly larger Aluminum conductor.
Once you have that heavier conductor, the voltagd drop for the same length wire is the same.
So, for example, for a few hundred amps, the voltage drop (which is what it's all about) might be the same with 4 ga copper and 2 ga aluminum. Remember, the only term of relevance is voltage drop, which can be calculated as current*resistance. Aluminum has a higher resistance for a given gauge, so the drop is higher. But that is easily mitigated with a bigger conductor. And since the density of Aluminum is like 1/4 that of Cu, the mass required for equal voltage drop is miniscule.
So my curiosity was more about mechanical longevity of CCA. The current carrying capability of Al vs Cu and how to engineer around it is well known.
Of course for the same price, and/or where the value lies, if Cu is a better value, great, but Al is still half or less than Cu on a conductor cost basis.