Every time there is a natural disaster, or bad weather, the power goes down for huge number of people when power lines are disrupted. Is there any technical reason that all power lines cannot be buried. They are where I live.
No technical reason, just cost.
A couple of different questions here. No, not just any old cable can be buried. Some can be–the direct bury kind can be put right in the dirt, and other kinds can be run underground if they’re sheathed in a conduit–but some will degrade underground, which can cause dangerous shorts.
For why we don’t just underground all of our cables, this Popular Science article explores the reasons why (as has been said, it’s mostly about cost).
I believe it’s considered inadvisable in areas subject to flooding by salt water.
We’ve discussed this before. It basically comes down to cost.
And the increased cost for underground lines is not just in burying them initially – it is a constant increased cots. Underground lines have higher power losses than overhead wires; that is a continuing expense every day they are used. Plus maintenance is more expensive on underground lines; they must locate the problem, then dig to get at it; that makes it longer & more expensive to fix.
Undersea cables have been around since the late 19th century. Is it that much more difficult to make saltwater-proof underground cables?
Not more difficult, if anything, easier nowadays.
Just more expensive.
My brother’s home does not have utility power. He is about 1/2 mile from the nearest power pole. If he were to connect up to PG&E the line will have to be berried with a pull box every 100 feet. When he checked in the cost about 15 years ago, it was going to be in the range of $35,000. This is 240 vac three wire large enough for 3 homes.
If you go large enough for a subdivision the line and voltages are going to be much large and more expensive.
Undergrounding distribution cables isn’t unusual. As you correctly point out, this protects them from being damaged during storms. Undergrounding transmission lines is very unusual for the reasons mentioned. However, transmission lines are less susceptible to storm damage because they are less likely to be downed by falling trees.
But much more likely to be damaged by someone digging.
And digging (by construction companies, road builders, landscapers, etc.) happens every day; major storms only occasionally (even with global climate change). Overall, power companies have found the risk of damage to distribution lines roughly equal.
I agree 100%, but I was making a slightly different point, which I will try to make more clearly.
Low-voltage (“distribution”) networks such as the one in the OP’s neighbourhood are sometimes undergrounded. High-voltage (“transmission”) lines are almost never undergrounded, except in very special circumstances (for example where an undersea interconnector makes landfall, or over short distances within a city). However, overground transmission lines are normally strung at a height where they are not vulnerable to damage by falling trees/branches. So, even though they are overground, they are not as vulnerable to storm damage as overground distribution lines are.
In my company’s networks business the term “cables” always refers to underground and “lines” to overground. I don’t know how universal that convention is.