The sinking of high voltage transmission lines presents special challenges, with the costs likely to be five or 10 times (in places even 13 times) the cost of overhead high voltage transmission.
It is not surprising that throughout Australia only a tiny percentage of the lines of 66 kilovolt (kv) and above are underground.
In the case of the lowest voltage category in this range there are 24 500 kilometres of overhead lines, but only 156 kilometres are buried.
Even in the most advanced classification, the 110 kv lines, only 4.6% of 3670 kilometres of lineage (178 kilometres) is buried.
The proportion of underground cable in the 132, 220, 275, 330 and 500 kv classifications is even lower.
Those costs to put power underground about 50 billion i believe...wouldnt be sauprised if half netword cabling or more is redundant in 50 years due to people having personal solar and batteries aswell as micro grid setups as many countries are now installing now
