Subject:  (Philips) (Maxey) Avoidance & shielding (fwd)
Date:     Thu, 14 Jan 1999 065244 -0600 (CST)
From:     "Roy L. Beavers" <rbeavers@llion.org>
To:       emfguru <rbeavers@llion.org>
--------------------------------------------------


---------- Forwarded message ----------
Date: Thu, 14 Jan 1999 10:33:27
From: Alasdair Philips 
To: "Roy L. Beavers" 
Subject: Re: (maxey) Avoidance & shielding (fwd)

I completely agree with Ed, below.  In fact the bulk of the public's
magnetic field exposure is due to underground cables - certainly in Europe
where most low-voltage (230/415 volt) distribution cables are buried.  It
is made MUCH worse by interconnecting neutrals by the supply companies to
limit over-voltage errors if a neutral gets broken - this practice results
in many error currents causing elevated magnetic fields over large areas
(complete streets, etc).

In practice very few people ( at least in Europe) live within 100 yrads of
a high voltage cable.

In some parts of the USA it is higher due to local HV distribution overhead
wires being run along streets - whereas in Europe local overhead wires
feeding houses tend to be 230/415 volt with very high currents!
Cheers

Alasdair



At 11:44 12/01/99 -0600, you wrote:
>---------- Forwarded message ----------
>Date: Tue, 12 Jan 1999 11:03:05 -0800
>From: Edward S Maxey 
>
>Hello Roy,
>The phrase "also high power lines by putting them 
>underground" in the message below alerted me.  A 
>couple points need to be made.
>
>1. The earth is NOT and effective shield of 50-60 Hz magnetic 
>fields.  Such fields penetrate soil almost as efficiently as they 
>do air.  Placing high power lines underground does not 
>significantly reduce the magnetic fields from such lines 
>because of the soil.  Rather, the reduction (if any) comes from
>the phase carriers being placed closer one to another thus 
>causing the magnetic fields from any one phase to more 
>effectively counteract those from adjacent phases.
>
>2.  If reduction of magnetic fields is the objective high voltage 
>lines are our friends.  A 20,000 volt 100 ampere line carries 
>twice the power of a 10,000 volt 100 ampere line while both 
>create identical magnetic fields.
>
>Cordially,
>Ed Maxey

 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Alasdair Philips    (aphilips@gn.apc.org)
Director, UK Powerwatch,
EMC Engineer and EMF-bioeffects researcher
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



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Reprinted with permission of Roy Beavers, http://www.feb.se/EMF-L/EMF-L.html