What are the pros and cons of copper versus aluminum entrance cables for a residence?

Question

Wire has to be buried for 50 feet and in conduit for 25 feet.

Answer 1

Copper can be smaller to go the same distance and still carry the same amperage. Alum is lighter and cheaper, but you will need to use a larger size to get the same capacity as copper. Alum is used all the time as Service Entrance Cable, more economical, usually slightly easier to work with.

Answer 2

Copper wire is a much better conductor of electricity and for the same amperage you can get by with a much smaller conductor in copper than aluminum.  Other benefits are that copper is a much better medium for heat transfer so when copper heats up it tends to get rid of the heat better than aluminum and at connections aluminum tends to shrink and swell more than copper increasing the risk for the wire to come loose at the connection and arc.  But if done properly both types of wire will preform well and give long life.