[TowerTalk] high tension wires

Jim Lux jimlux at earthlink.net
Sun Aug 27 19:13:05 EDT 2006

At 02:37 PM 8/27/2006, Gayle Kaye wrote:
>I found you by doing a search on google . I am just plain ol'John Q.
>Public who's trying not to panic. So try to use some plain talk. It
>would be appreciated. I am good with a dictionary.
>I just heard there is going to be a 500kV high tension wire built in
>our valley to help bring more electricity to the "city" 12 miles
>away. Of course I chose to live in a semi isolated area because I
>like it and feel upset by this "major intrusion."  My question to you
>is about the safety of this "wire" being put through our valley, and
>how concerned should we be?

The safety of the line is probably related to things like construction 
equipment when they build it, more than anything else.

>Not being an expert on electricity and it's effects I am looking for
>some information so I can be informed rather than just plain scared.
>I have two girls 11+14, livestock, and an orchard that helps to
>supplement my lively hood as a teacher. How concerned should I be?
>The wire will be about 5-700 feet from my house. there about 30 homes
>where it will pass and being a small town the is of course some
>hysteria going on. Please let me know your opinion or where i can get
>some information to be able to conclude my own opinion.

There was a widely publicized sensational book more than a decade ago 
called "Currents of Death", virtually all the claims of which were either 
subsequently refuted or found to be the result of something else.  I'll 
give some specific examples lower down, but, you should bear in mind that 
these kinds of books tend to live on for a long, long time, particularly 
since they pop up everytime someone googles it.  These sorts of things are 
good for news ratings too: "new power line responsible for increased 
cancer? Find out at 11!" (never mind that the story at 11 says nope, it's 

>Trying not to panic,

Don't panic..but be aware...

Here's the overall scoop.

40 odd years ago, someone did a statistical analysis of occupation and 
cancer incidence and found that people who worked in electrical switchyards 
and similar occupations had a slightly higher incidence of cancer. (along 
with lots and lots of other professions..) At that time, they hadn't 
controlled the statistics for things like age, smoking, income, etc.  all 
of which have huge effects on cancer incidence.  No big deal in general.. 
there are analyses like these all the time, insurance and public policy 
folks use them to set rates, figure out how much to budget for health care, 
predict future population.

About 10-15 years later (now about 20 or more years ago), someone said, 
hey, what if the thing for switchyard workers is due to electric 
fields?  So they figured, if we look at other populations that are exposed 
to high fields, we should see an increase in cancer.  Then, because at the 
time, actually measuring the fields was expensive (we're talking about a 
couple grad students and a professor doing the research essentially part 
time), they figured, if we get a map of Denver and the surroundings, and 
assume that power lines result in fields (not necessarily valid) then we 
might see a correlation between how close you live to a power line and 
cancer incidence.  Remember, this is back in the days when PCs were brand 
new, so most of the work was done manually, and there were lots of 
approximations.  They took regions of the city for which they had cancer 
statistics, and measured the distance to power lines with a map.  Sure 
enough, they found a correlation.. they published a paper, and it got 
picked up by the news.

What that study did NOT do (and to give the authors credit, they were very 
careful to say so in the paper) was:
1) Figure out if there was some other reason there might be a higher 
incidence.  Notably, neighborhoods with power lines have lower housing 
prices (because the lines are ugly), which means that people with lower 
incomes live there.  Lower income is definitely correlated with higher 
cancer (less access to health care, more carcinogen exposure at work, etc.)
2) Actually measure the fields.

The other very important thing is that nobody was proposing a credible 
biological mechanism by which the fields might cause cancer.

This story came out at a time when PCs and video display terminals (VDTs) 
were becoming much more common at work, and people were reporting aches and 
pains and "weird things" that they attributed to electromagnetic radiation 
from the displays. The most famous study there is the Kaiser study that 
showed a correlation between VDT usage and miscarriages.  If you recall, 
there was a bit of a recession around then, so things like this also wound 
up be used as a negotiating tool by unions: We deserve a raise because 
you're killing us with EMF from terminals.  {Turns out in the various VDT 
and PC studies they eventually attributed the problems to ergonomics.. 
people aren't designed to sit in traditional deskchairs staring at a screen 
all day...}

So there was a lot of attention to fields and health. And a lot of news 
stories. And a lot of people jumping on the bandwagon to survey your house 
or business for fields, for a nominal fee, etc.

Subsequent to all this (in the last 10-15 years) there have a been a 
variety of very well done studies, where they actually measured the 
electric fields, and controlled for previous health history, occupation, 
etc.  The result of all this is that all the studies have found is that 
there is no statistically significant increase in cancer due to living 
under a power line, at least from the electric fields.  Sure, there are 
increases, sometimes (but there are also decreases.. they don't get on the 
news), but they can be attributed to things like income, environmental 
contaminants, and the like.

This is not to say that a power line is a wonderful thing to live next 
to.  It IS sort of ugly. It does make noise (crackling and hissing when the 
weather conditions are right). It's real, real visible, so it can be used 
as an excuse for something else someone doesn't like. The construction 
process can be disruptive, noisy, etc., like any construction  (although 
these days, with helicopters, they can drop in new lines without having to 
bulldoze huge swaths of the countryside).  And older power lines may be 
associated with industrial contamination with things like PCBs (which were 
used for insulation in big transformers, and the like), not to mention just 
plain old stupid (in retrospect) things like using PCB contaminated oil as 
a spray to keep the dust down on the access roads.  This sort of thing is 
quite unlikely in today's regulatory environment.

There are also legal restrictions on what you can and cannot build directly 
under the line.  For instance, around here (southern California), you can't 
build a permanent structure, so you see lots of wholesale nurseries, 
christmas tree farms, and pipe corrals for horses and livestock under the 

There's a very authoritative source of information on the power line/cancer 
thing at:

As for aesthetic concerns and stuff surrounding construction hassles, 
you're sort of on your own.  The power company engineers tend to look at HV 
transmission lines as things of beauty and good engineering, particularly 
if the technology is novel or the route particularly rugged and 
challenging.  They also tend to be pretty focussed in on the cost/benefit 
ratio.. they solve problems with getting power from here to there, and to 
most engineers, that's a good thing.

Good luck, and feel free to ask questions..

James Lux, P.E.

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