Max Sag occurs at max. temp. in most cases. You need to work out the max. sag from other cases such as wind or icing in which the conductor tension reaches the max. tension. Max. tension is limited to UTS/F.O.S, sometimes EDS may become a critical factor when you calculate the sag-tension.
Tower height is decided this way:
1.You calculate the max.sag at basic span to get the height of the bottom crossarm height, you need to consider the electrical clearance to the ground as well.
2.You decide the vertical phase spacing and earthwire to uppermost phase distance which you may...