What is the percentage of loss allowed of considered in different elements of network? ( 33 kv lines, 11 kv lines, substations and LT lines. what is the POWER allowed to transmmit in such lines ? what is the conductor use.

In my system the T&D loss is in the order of 30% of injection energy to billed energy. I have seen that most other country in west, the LOSS level is beloww 10% all inclusive. Please share experience for remedy of the problems.