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High power transmission lines: underground?

  1. May 2, 2013 #1
    In the Midwest (Iowa, etc.), we get plenty of storms, mostly Winter, and power lines go down frequently.

    Someone is about to build a new high-power transmission line across my County (and too near my property!!), and I can't figure out why it is not mandatory in the 21st Century that all electrical lines, regular and high-power, be buried underground.

    It's been suggested that the factor is cost, but how can a large buried conduit be more expensive than towers and lines and guywires and thousands of insulators, etc. etc.???? Once buried, and using modern materials, no ice nor wind nor tornado will interfere; no "stray voltage" or other real or imagined health risk will escape; and, best of all, no ugliness will scar my fine prairie view.

    Any good reasons, engineering-wise? Thanks!!
  2. jcsd
  3. May 2, 2013 #2


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    In the ground, it is not sufficient to have a few insulators every kilometer - you have to insulate the whole cable. Losses should be higher, and you still have stray voltage. Digging up the ground is expensive, too, in particular if you have to cross existing infrastructure.
    Towers are easy to construct, and you don't need many of them. And cables are cheap, if you don't have to isolate them.
  4. May 2, 2013 #3

    jim hardy

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    Insulation for that voltage is REALLY expensive;
    both installation and repairs require excavation.

    Believe it or not, utilities spent a fortune developing aesthetic power line towers.
    When you see a monopole with cantilevered, curved crossarms and single suspended insulators, please appreciate these replaced awkward looking triangular supports that are much easier to design.

    But we're not here yet:


    Last edited by a moderator: May 6, 2017
  5. May 2, 2013 #4
    I've always been told that it was because high voltage cables had too much capacitance.
    This capacitance caused excessive current.
  6. May 2, 2013 #5


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    I don't know why it isn't mandatory in the 21st century that we have all of these surface roads taking up space. Why don't we dig tunnels everywhere?
  7. May 3, 2013 #6


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    This is definitely one of the coolest things I have ever seen. The other pics on the link are equally impressive.

    A man and a woman holding a 500,000 volts worth of cable. Ya, sounds about right:)
    Last edited by a moderator: May 6, 2017
  8. May 3, 2013 #7
    However, seeing mile after mile of that would look a bit creepy to me.
  9. May 3, 2013 #8
    In addition to the other factors mentioned, I understand there is a heat problem. It's much harder to dissipate the heat underground. You may notice that power lines hang lower in the summer than they do in the winter. Granted summer and winter have much less effect underground but how do you deal with the change in length of the cables underground between heavy and light loading?
  10. May 3, 2013 #9

    jim hardy

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    Who hasn't seen this one at Disneyworld?

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