PWSlack is right. Selecting a conductors for H.V and L.V systems will need a consultants support for the start till knowledge and experince is gained. There are alot of factors to consider when selecting areal condcutors for a distribution system. This all starts from the project investigating, scoping, and the design phase. Some of these factors include;
1. the line span
2. mechanical loading from wind speed, still air, sun, rain, ice, tension from suspension and pin insulators, pole top construction type
4. voltage and current to be transported
5. conductor expansion rate
6. line support structure, pole top construction type, and protection.
7. line route and geography
The first thing the consultant may ask for is your design requirements. Based on that, the conductors may be determined. Read on the Design and Construction of Distribution Systems from the net, there's alot of free books in PDF format you can download on the topic.