EMF Question

[urbanxer]

New 345 kV transmission towers are going up here in N.E. USA to replace 115kV along the same right of way. Of course the cry of EMF's have come up again. Would it be correct to say at the same damand, the 345 line would produce one third the EMF of the 115 line? EMF is a function of current correct? I lost some books but isn't it also true that elecrtic fields drop off at the square of the distance. So the 100 foot steel 345 tower would have significantly less EMF at groung level then the 50 foot wood 115 tower. I'm asking all this because it would be interesting (if correct) to see if the media would pick up the story that in fact the new higher voltage lines produce a fraction of the EMF of the old line. Thanks in advance to anyone who contributes.

 

[itsmoked]

A big part of the EMF as relating to power lines IS a function of the voltage. So it's going to go up because of that. But it would be interesting to see if the voltage/height trade off makes the difference up.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[cuky2000]

The enclosed link is a comparison of magnetic field profile under a typical 115 kV and a 345 single circuit transmission line.
I hope this could help:

http://cuky2000.250free.com/EMF 155 vs 345 kV.jpg

 

[NormGA]

Years ago I assisted my young daughter with a science fair project titled: EMF's: Higher in your home or near power lines?

After making many, many readings with a Gaussmeter we determined that the magnetic field levels were much higher in the average home than near power lines or substations. The reading near a hand held hair dryer was over 1000 mG. The highest reading I found near a transmission line was about 5 feet from a 115 kv low profile bus in a substation, and that was only a couple hundred mG. So if you are worried about EMF you need look no further than your own home. If you're really worried about it, don't sleep under an electric blanket. That's about 75 mG and the exposure time is long.

BTW, the numbers we got under local 115 kv lines corresponded real well to the numbers on the Cuky2000 charts in the link above.

NormGA

 

[Skogsgurra]

As I have said before - and will continue saying for as long as I can talk/write: There are NO PROBLEMS WITH ELF!

EMF is quite another story. If there is an EMF of more than 50 - 60 volts and you touch it, it may kill you. That is also known as electrocuting.

But, please, try to understand that a magnetic field with low frequency (ELF = Extremely Low Frequency) has never been a problem for living organisms. It is only when you approach 50 - 100 millitesla (500 000 to 1000 000 mG) that any influence on humans can be detected. Such field strengths do not exist in nature or close to electromechanical devices. Only inside motors and generators.

I cannot understand why otherwise intelligent and well informed people at all do worry about ELF. I really can't.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[itsmoked]

But what if they're really nasty ELFs! Like with knives?

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[jraef]

Correct me if I'm wrong, but I'm in a not picky mood today.

Isn't EMF the acronym for Electro-Motive Force? Electromagnetic Fields would be EF, or maybe EM Fields, but EMF is already taken as an acronym within this engineering discipline.

By the way, I live underneath a 230kV distribution line and I have no ill effffffecccvctssa,lmnpvbiajh nas/dlk,fb ap;rkojngb!

 

[Skogsgurra]

Yes, Smoked. Steel knives will concentrate the flux considerably. You have to consider that...

And, yes, Jeff. As I said EMF of more than 50 or 60 V may be letahl (under the right - or, rather, wrong - conditions). And, yes again, the acronyms are taken many times. But the electric allergy/sensitivity/luny business people do not know about electricity. So they coined their own TLA back in the eighties. They use ELF for Extremely Low Frequency (magnetic field). But everyone has forgotten what the TLA stands for. So, nowadays, it is something you use to scare the cr-p out of people with.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[jghrist]

EMF stands for Electric and Magnetic Fields. These are not the same as electromagnetic radiation like radio waves, x-rays, or light. Electric fields depend on the voltage and magnetic fields depend on the current.

Most health concerns have been with magnetic fields.

I think that Power Lines and Cancer FAQs at

http://www.mcw.edu/gcrc/cop/powerlines-cancer-FAQ/toc.html

gives a comprehensive and fair treatment of the subject.