Although it is made of steel and iron, the ht(high tension) xlpe cable is not more stronger than lt(low tension) al xlpe cable. A super typhoon can scar the power grid. Then why can't we bury all high voltage extension cord underground like urban underground 3 core steel wire armoured cable, so that we can do it once and for all, no matter how many typhoons?
At present, there is no effective electrical wire insulation to be used as the outer sheath of the ht(high tension) xlpe power cable transmission. Therefore, the extra high voltage power cables are exposed and cannot be buried underground.
There are distributed capacitances around the high voltage grounding cables, and current can leak out through these capacitances, which increases consumption on the one hand; on the other hand, if any animal approaches, there is a danger of electric shock.
Air is an insulator, but the earth is a conductor. In the air, you only need to put the heavy duty electrical wire directly there, but in the ground, you need to add layers of insulating casings to the high voltage electrical cable, otherwise the electricity in the wires xlpe insulated power cable not go far, and there will be little leakage left.
Underground electrical wires are more complex in structure than overhead high voltage power cables, have higher technical requirements, and are difficult to manufacture and construct. In addition, the aluminium electrical wire is buried underground, so it is not easy to find faults, and it is also difficult to repair and maintain.
Generally speaking, the cost of underground electrical wires of the same voltage level will be several times or even dozens of times that of high voltage extension cord in the air.
No one wants a power outage, and once something goes wrong, it is necessary to "dig three feet in the ground" to check and repair the high voltage single core cable.
First, they have to go through the procedures for digging the "underground high tension power lines"; then, they have to work overtime to dig tunnels; then they have to check the underground electrical wire one by one to find the fault point; finally, they can find the right medicine for the fault point. This delay is all the time of the big guys, and the staff responsible for power supply cable repair is also very innocent, cause they really want to restore the power quickly.
To sum up, burying ht(high tension) xlpe cable underground has both safety and economic problems.