I am not sure if this is a GQ or should be in IMHO.
When I first moved to the United States (from India) 8 years ago, it amazed me to see the power cables strung up on wooden poles. The power to the house itself came via underground cables but it was delivered to the neighborhood on these tall wooden poles. I had never seen anything like this except in small towns and villages. But here it was everywhere except in the downtown areas.
I know that this is probably a holdover from the past and the economics stands in the way of moving from a pole based distribution system to an underground one. But surely, neighborhoods and suburbs that have sprung up in the last couple of decades or so could have underground cables bringing in power to the neighborhood – but the wooden poles are still being used! Not only are they an eyesore, but more importantly, during a hurricane like Ike they have put almost all of Houston in the dark.
Any dopers know why we still have these wooden poles?
Inertia and cost of replacement in a lot of places, I would assume. The suburb I was born in had underground power in the early sixties. The suburb I live in now, dating from the early fifties, does not.
Main distribution lines with their higher voltages are above ground, and a lot of those follow main roads.
It does indeed depend on the locality. My own neighborhood, which is about 40 years old, has underground power cables.
Underground cables have their own costs though when it comes time to repair or replace them. I don’t know how the numbers work out, but it’s not necessarily a no-brainer decision.
Sure, they get knocked over whenever there’s a light breeze, but they’re easy and cheap to replace. Underground cables are more reliable and last longer, but more expensive by an order of magnitude or more to build and service. In northern climates, it may be too difficult to install conduits underground due to freezing soil. In southern Florida, you can’t put anything underground because you’ll drown.
It’s a lot easier to put in underground cables in new neighborhoods, and a lot of them will have them if the builders are willing to foot the bill (or local codes require it.) But there’s no motivation to bury existing above-ground lines in most places; the cost is either prohibitive or it just can’t be done.
OP should keep in mind that the area of the States that is exposed to hurricanes or weather that otherwise can damage power lines on poles is a small percentage.
In my neighborhood the power lines come to the house from the pole–nothing is underground. I can see the three lines and where they connect to the house. There’s never been a problem with the lines.
Out here on Long Island (NY), there is a dispute as Southhampton town wanted LIPA (the electricity distribution company) to place a planned main feeder underground - the addition cost is 8 million vs above-ground on poles, plus additional cost throughout the life of the feeder for maintainence.
Not sure if this Newsday story will remain, but while it’s there: Newsday | Long Island's & NYC's News Source - Newsday
And though hurricane-prone areas would see a lot of benefit from the wind-proof nature of buried power lines, these also tend to be the same areas where the water table is so high they have problems keeping dead people buried 
. (See also friedo’s south Florida comment.)
For what it’s worth, here in St. Louis we had a few big summer storms the past couple of years that left thousands of people without power for weeks in some instances. The power company was scolded for failing to keep up with tree trimming and line maintenance, so they announced this big program to start trimming trees and converting significant sections of the grid from poles to buried cables. Our rates jumped 30-50% in some cases for their trouble (expiration of price regulations had something to do with it too, IIRC)
For main power feeder lines, it can be very difficult (= expensive) or even impossible to put these lines underground. (The ground conducts electricity, after all, and high voltages mean they have to be kept farther apart – thus the ‘wings’ on overhead towers holding the wires from each other.)
Thus even if Houston had been wired with the neighborhood distribution lines and lines into houses underground rather than on wooden poles, they still would have been without power. A storm like Ike was powerful enough that some of the main feeder lines would have been knocked down anyway. Also, much of the electrical problems relate to the flooding of transformer stations, switching substations, etc. That too would have happened even without lines on wooden poles.
Why do power lines electrocute people if they are properly sheathed? I’m thinking of tbonham’s comment about underground power lines and the ground being a conductor.
I know that birds can sit on them just fine on telephone poles, but if a person hangs from one, they get electrocuted due to weight?
If the lines have a proper covering over the metallic wires, why would this happen?
The U.S. was one of the first parts of the world to electrify, and compared to much of the rest of the industrialized world, the U.S. is big and spread out. All in all, it was much cheaper and easier to use utility poles. Since this was the default, even new neighborhoods were built with utility poles. And contrary to your comment about underground conduits to the individual homes, many houses in the U.S. (especially those built before 1970 or so) still have overhead lines that are strung from utility poles to the houses.
In some more upscale neighborhoods, it was recognized that utility poles were an eyesore. In my grandfather’s neighborhood in Houston, built in the early 1960s, the utility poles were strung along the back yards. (BTW, his power is still out as I write this, going on 7 days since the storm.)
As time went on, utility companies began to recognize that utility poles have low upfront costs, but high maintenance costs (e.g. tree trimming, repairing downed lines, etc.).
As utility companies realized that underground conduits are more reliable and cheaper in the long run for them, they began to require that the new neighborhoods being built in recent decades have underground conduits instead of utility poles. This is also because the municipality and utilities can typically require the developer to install the underground conduits, and it’s no more expensive for the utility company to pull wires through conduits than to string wires on poles–in a new neighborhood. Also, it’s not that expensive to add conduits when the road is being put in. Finally, the developers and potential buyers liked the look of these new utility-pole-free developments.
For underground high-voltage lines, the big issue is not that the ground conducts electricity. The main issue is heat dissipation. The conduits themselves are encased in concrete duct banks that serve to insulate the cables from the ground. A typical duct bank is typically about 4 feet by 2 feet in cross-section.
Power lines in neighborhoods are typically a few hundred to a few thousand volts. These lines are insulated. So long as the insulation is intact, they should be safe, but if a line is down, you can’t count on the insulation being intact.
The high-voltage cross country lines are anywhere from tens of thousands to hundreds of thousands of volts. They are not insulated. You are looking at bare wires. This is because it would take as much as a foot of insulator to cover these, which is not practical. Birds don’t get electrocuted because they are not grounded. If a bird touches two wires, though, or a wire and the ground, you’d be looking at charred bird.
There’s a picture in a physics book I used (Halliday & Resnick) with a utility worker working on a 500 kV (500,000 volt) live line by hand. He is sitting on an outrigger of a helicopter, so he is not grounded. The helicopter outrigger is connected up to the line, so the man, the helicopter, and the line are all at the same electric potential (i.e. the same voltage). So long as they don’t touch another line or the ground, they are safe.
Anecdotally, I’ve heard of a military fighter pilot who bailed out of his jet, and whose parachute was entangled and hanging from high voltage lines. A farmer approached him with a ladder, intending to rescue him. The pilot realized that if the farmer’s ladder touched him (or got near him), they would both be killed. The pilot reportedly had to point his service pistol at the farmer to dissuade him from approaching any closer.
Video about a High Voltage Cable Inspector. And yes, “He is sitting on an outrigger of a helicopter, so he is not grounded.” 
He says at the end that he’s only been afraid of 3 things…
This varies a bit. In some areas, only the wire between the transformer and your home will be insulated. In other areas, the entire distribution line will be insulated. Often the insulation is only good enough to prevent the line from shorting out against local vegetation. The insulation in those cases isn’t designed to prevent you from being shocked should you accidentally come in contact with the line.
The insulation isn’t there to protect you, it’s to stop the power from going out too often.
Connections around transformers and such on poles are often not insulated. Not only can people get electrocuted from them, but birds and squirrels often get electrocuted by them as well.
Thanks guys. Learn a new thing every day! And here I was at work all afraid of 480v three phase power…pffft!
FWIW, Canada and Australia also have a good portion of their electrical distribution system above ground.
Electricians have often said that 240V AC is the most dangerous. !20V you are able to pull away from, while 480V will throw you and break the connection, but 240V is serious that you can’t break away, but not enough to throw you, so you are stuck there getting shocked.
All these very high voltages are pretty rare for most electricians, who work with 480V and down. These are power company circuits, which only specialized electricians work with regularly – and they are very aware of the risks involved, and treat them with care.
Depends on the particular danger. Shock is one thing but for arc flash, industrial 480-600 V presents the greatest danger, hands down. The amount of energy released in an arc flash incident depends on a number of variables, particularly the current capacity of the circuit in question. With a voltage high enough to sustain an arc over a fair distance and instantaneous-trip currents in the high tens or even hundreds of thousands of amps, these circuits can deliver arc flash energies that can kill you dead up to several feet from the point of origin.