Every new neighborhood I’ve seen has underground lines. Why do you think we are repeating past mistakes?
I don’t buy a couple of your arguments either. Around here, whenever the power has gone out, it has been restored within hours, which is not long enough for food to spoil. Also, if a car has gone off the road already, it’s probably going to hit something. The fact that it hits a utility pole isn’t the fault of a pole being there. If the pole wasn’t there it would likely just hit something else. The points about safety, reliability, and asthetics are valid though.
Power is generated at a relatively low voltage at the generators. The losses in the line have a lot more to do with the current than the voltage, though, so transformers are used to step up the voltage. The higher the voltage, the less loss you have in the lines, but higher voltages are also more dangerous. You have to keep them up higher so people can’t climb up and electrocute themselve, and you have to keep the lines spaced farther away from things so that the electricity doesn’t arc over (the higher the voltage, the farther it will arc). Power is often generated very far from where it is used. Just because you have a power plant nearby doesn’t mean your power comes from there. Most power companies have a bunch of small plants, but only a small number of really big plants, and the big guys supply most of the power for the entire system (nuke plants are the biggest, usually followed by a couple of coal fired plants). In order to get the power to where it needs to go, they transform the voltage to a very high level (tens of thousands of volts), and run it over the really high voltage transmission lines that you see (the ones with the really big towers). This goes to a substation, which transforms the voltage down to a lower level (a few thousand volts), which then goes around to all of the neighborhoods. Inside the neighborhoods, transformers take the voltage down to what goes into your house (240 center tapped, so you can get both 120 and 240 circuits out of it). It’s very inefficient to carry power at this low of a voltage, so usually only a few houses will be fed from a single transformer, so in that respect transformer placement is important. These transformers are in large boxes on the ground (or in older above ground systems they’ll be in big cans on the utility poles). Substation placement is important too, since fewer substations means longer distribution wires and more wire losses, but then no one wants a substation in their back yard (there are many folks who are convinced just being near this stuff is bad for your health).
I’ve never seen a high voltage transmission line that had insulated wires. The distribution lines will sometimes be insulated, but usually won’t. If they are underground they will always be insulated.
Underground wire breaks are rare, but when they do happen they can be a real bitch to find. A friend of mine who works as a transmission and distribution engineer was telling me how they go out “thumping” sometimes. What they do is “thump” the broken line with a high voltage, and literally walk around in the area where they think it might be broken, listening for the thumping sound, and watching to see where the worms all come up out of the ground.
Also, people will often break underground lines when doing construction work. At least with overhead lines it is easy to see where they are. With underground lines, the only thing you have are diagrams showing you where the wires are suppsoed to go, and sometimes they aren’t accurate. People have dug into the ground and found a wire, only to have the power company come out and shrug, having no idea where the wire came from or where it goes.