The attenuation is more from salts and water content in
surface soil. E-fields are not completely attenuated.
The oil industry uses E-field for monitoring head
information. E-fields communicate from the drill head back
to the surface over a distance of several miles *except*
when there are salt water layers.
- Robert -
On Tue, 9 Mar 2004 11:39:51 -0800
"Steve Toyama" <[email protected]> wrote:
> Is the electric field completely attenuated under ground
> and is it due to
> the water and iron in the ground being conductive?
>
> Curious,
>
> Steve Toyama
> ----- Original Message -----
> From: "robert Macy" <[email protected]>
> To: <[email protected]>; <[email protected]>
> Sent: Tuesday, March 09, 2004 10:11 AM
> Subject: Re: Pace makers, speakers, magnetic fields
>
>
> >
> > Electric field of course is attenuated being buried in
> the
> > ground. But [to me] it is unlikely E-fields do much to
> the
> > body since the body is conductive and therefore is
> > "self-shielding". With the conductivity of the body
> like
> > sea water, there is little self shielding of mag fields
> > below 40KHz.
> >
> > Remember that the magnetic fields drop by the ratio of
> the
> > square of the distance to the separation.
> >
> > For example, tower mounted high tension 115KV lines are
> > around 12 feet apart and buried lines are what? two
> feet
> > apart? That reduction in separation distance drops the
> mag
> > field by 36 to 1 at the same distance from the pair of
> > wires! Big change.
> >
> > - Robert -
> >
> >
> >
> > On Tue, 09 Mar 2004 09:36:03 -0800
> > Richard Nute <[email protected]> wrote:
> > >
> > >
> > > Hi Robert:
> > >
> > >
> > > > Later the high tension towers have been replaced
> with
> > > > underground transission lines as part of the
> Guadalupe
> > > > corridor beautification plan.
> > >
> > > Hmm. I don't believe burying transmission lines
> > > attenuates either the magnetic or electric fields.
> > > Obviously, something must be done to attenuate the
> > > electric field to prevent shocks above ground due
> > > to a body crossing too many equipotential lines.
> > > Attenuating the electric field may or may not also
> > > attenuate the magnetic field.
> > >
> > > Comments on attenuation of electric and magnetic
> > > fields of buried high-tension lines as compare to
> > > overhead lines?
> > >
> > >
> > > Best regards,
> > > Rich
> > >
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