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Powerful effect from high voltage transmission lines

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  • Steve Nazigian
    For an art project, people illuminated 1,301 florescent bulbs powered solely from the electro-magnetic effects of overhead power lines. Short paragraph and
    Message 1 of 2 , Feb 28, 2008
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      For an art project, people illuminated 1,301 florescent bulbs powered
      solely from the electro-magnetic effects of overhead power lines. Short
      paragraph and awesome photographs here:
      http://gizmodo.com/361390/1301-florescent-bulbs-lit-solely-by-magnetic-
      fields
      It just underscores the fact that power transmission lines have very
      real and powerful effects from the quantities alternating current they
      carry. These look like 40 watt or 60 watt tubes, so I would presume
      that small section of ground is supplying at least 52,000 watts and
      probably a whole lot more.
    • kallio_mn
      ... Actually, they are being lit by the Electric field, not the Magnetic field. Every time electic current produces a Magnetic field. Any potential at a
      Message 2 of 2 , Feb 28, 2008
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        --- In humforum@yahoogroups.com, "Steve Nazigian" <stevenazigian@...>
        wrote:
        >
        > For an art project, people illuminated 1,301 florescent bulbs powered
        > solely from the electro-magnetic effects of overhead power lines. Short
        > paragraph and awesome photographs here:
        > http://gizmodo.com/361390/1301-florescent-bulbs-lit-solely-by-magnetic-
        > fields
        > It just underscores the fact that power transmission lines have very
        > real and powerful effects from the quantities alternating current they
        > carry. These look like 40 watt or 60 watt tubes, so I would presume
        > that small section of ground is supplying at least 52,000 watts and
        > probably a whole lot more.
        >

        Actually, they are being lit by the Electric field, not the Magnetic
        field.

        Every time electic current produces a Magnetic field. Any potential at
        a distance produces an Electric field. An AC power distribution line
        would produce a both a time varying Electric field and a time varying
        magnetic field. The magnetic field has no effect on the gas in the
        tube. It is the Electric field (measured in volts per meter) that
        causes the potential difference across the tube causing it to glow.

        A good number of very high voltage transmission lines are DC, not AC.
        These create a very large Electric field (say 400 KV at the wire and
        zero volts at the ground. For these lines, both the Electric field
        and magnetic field would have a large fixed offset with the only
        changes being due to changes in the far end load.

        These fields drop off however. The rate of drop off from a line
        source is directly proportional to the dustance from the source.
        (1/R). The worst case field will be directly underneath the
        transmission line. Depending on tower height, number of conducters,
        and transmission line voltage, the field strength can be close to 4
        KV/meter near the ground.

        There is a power line alongside a road in a nearby neighborhood with
        homes set back about 100 feet from the road. One of the residents
        constructed an above ground swimming pool directly underneath the
        power line!

        Kallio
        Minneapolis, Minnesota.
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