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Posted By: kiwi health & high voltage - 06/18/05 12:16 PM
A big topic of discussion here in NZ right now is ELF emmissions in the immediate vicinity of overhead HV transmission lines and the effects on the human nervous system.

A recent T.V. documentary here showed a meter which measured 0.1 micro- teslas in a typical home with the fridge and the T.V. on. Then measuring 1.5 micro teslas in the back-yard of a house directly under a 220kV transmission tower.

The World Health Organization recommends that 0.1 micro-teslas are O.K. but 1.0 micro-teslas are not O.K.

Italy and one other European country have now legislated to segregrate HV transmission lines from residential land.

Does anyone else have any ideas on the elf emission debate ?

Would an earthed shield around the HV lines running over houses solve this problem ?
Posted By: C-H Re: health & high voltage - 06/18/05 03:17 PM
My view on this is extremely biased as I install equipment that exposes the operators to magnetic fields far greater than this. Sometimes the operator has the electrodes touching the body with 10kA flowing in them. In the conductors, not the operator [Linked Image] As the electrodes are about a foot apart, the magnetic field cancels some distance away from the electrodes. Nuts and other small metallic objects have a field day near the electrodes...

As far as I know, there haven't been any recorded short term effects on people from this despite half a century of widespread use.

Long term? Don't know.

Would I want to live right under a 220kV line? No! Apart from EMF, those wires can come crashing down. Not to mention bird droppings from the chatter party on the wires...
Posted By: gideonr Re: health & high voltage - 06/19/05 12:15 AM
Anyone who lives near the Underground (Subway) in London will also be exposed to large fields as the trains run on dc and tend to pulseate as the contact with the rail/cantenary varies.

You could only effectively sheild with some kind of ferrous material which would be impractable for a whole house.

In any case, at what level is the increased risk? We have Radon gas seeping into some houses here, and people still smoke cigarettes!
Posted By: Alan Belson Re: health & high voltage - 06/19/05 12:55 AM
And the same people who prattle on about 'Pylons', give their young children mobile phones.
Posted By: jooles Re: health & high voltage - 06/19/05 09:22 AM
We were looking once at houses in Portugal to buy. The idea was to use it as a holiday home and to rent it out when we don't want to use it ourselves.

There was one in particular that was beautifully appointed and would have been superb, but for the power lines whose path swooped straight across the upstairs balcony! The lines looked as if they where close enough to touch, although there was a perfectly safe clearence -- it was the optical illusion of being right under them.

Not sure of the voltage: I would guess it was 150kV, but the line was buzzing like a hiveful of bees. The internet says there is an effect called Corona discharge that causes this noise.

Whatever the scientific evidence for the risks of electric and magnetic fields, I'd rather not risk being deprived of a good sleep because if it sounds as loud as that in the day, then at night it would be intolerable.

The only good thing would be that thing of standing under the lines with an old flourescent tube and playing 'light sabers', but I should think the novelty would probably wear off very quickly [Linked Image]
Posted By: djk Re: health & high voltage - 06/20/05 02:25 PM
What I don't get is that there is no evidence of massive cancer clusters in power workers. Lets face it, someone who's has spent their life ontop of, beside, sitting on, having lunch near etc high voltage AC cables would be the most likely person to have any problems.

So, I'd say if the power workers have been doing it for over a century it can't really be that big of a deal.

I'd agree though, I wouldn't fancy a power line that close to my house. Noisy and ugly!

I'd be far more concerned about getting sunburnt than I would be about A/C power lines to be quite honest when it comes to cancer risks.

Smoking, Pollution, excess use of volitile cleaning chemicals, pesticides, radon gas, dental and medical xrays and their overuse.. food additives etc seem to pose far more of a risk.

I'm not even very concerned about mobile phones. Ionising radiation sources and chemicals are what worries me most!

[This message has been edited by djk (edited 06-20-2005).]
Posted By: Trumpy Re: health & high voltage - 06/20/05 11:50 PM
Dave raises a very interesting point here.
We are monitored here annually with various tests to make sure that nothing untoward is going on with our bodies.
I have to agree though, surely anyone that works that close to the lines, has to be a litmus test for everyone else.
However, this aspect of the power-lines vs. cancer has never even been mentioned.
Instead, the media tends to go for the more emotive side of the story.
One thing that a lot of people here in New Zealand seem to forget, is the fact that in a lot of places, the Asbestos pipes that fed water to thier houses are either still in the road or have only just been removed in the past few years.
It seems that people here only blame things that they can see. [Linked Image]
Another thing about using a Gauss meter is the rule of distance when it comes to radiation sources, I can't be sure, but I seem to remember that the field strength decreases by a multiple of 4(?) of any unit distance away from the source.
{Could someone please correct me if this is in-correct?}
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Italy and one other European country have now legislated to segregrate HV transmission lines from residential land.
In my opinion, this whole problem has come about by urban sprawl, the power lines were more than likely there before any housing was.
To a degree, any councils and developers really need to bear some of the blame for the reason why houses are under the lines in the first place.
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Would an earthed shield around the HV lines running over houses solve this problem ?
In a word, no, in fact it would cause more problems than what it would solve.
At 110 or 220kV, the Eddy currents flowing in the shield would be horrendous, not to mention the problem of Flash-over between the bare line and the shield.
The last thing you want near an HV or EHV line is an earthed conductor anyway, that's why they use insulators on pylons.
Posted By: pauluk Re: health & high voltage - 06/27/05 07:45 PM
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What I don't get is that there is no evidence of massive cancer clusters in power workers.

Nor is there any evidence of such in telephone switchmen, who for over a hundred years have worked in equipment racks surrounded by coils, solenoids, and relays generating various steady and pulsing fields.

If there was any real concern, surely we would have seen some sort of higher average occurrence rate in those exposed to strong fields regularly by now?

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I'm not even very concerned about mobile phones.
Over in North Walsham -- about 10 mi. from here -- there's a protest going on about the new TETRA antennas which have recently appeared on the town's police station. It's funny how the people never complained about the old VHF and UHF antennas, which have been there for years.

I've never heard of any protests over UHF TV masts either, which on the upper end of the band are on near-enough the same frequencies as cellphones, but with a much higher ERP.

Have a look at this site and see what you think:
http://www.emfs.info/



[This message has been edited by pauluk (edited 06-27-2005).]
Posted By: djk Re: health & high voltage - 06/27/05 09:49 PM
The ironic thing about mobile phone mast protests is that the bigger number of masts that go up the weaker the signals you're going to be exposed to are.

i.e. if you're in a good coverage area your mobile uses far less power to connect to the cell mast!

----

Also, with regard to the transmission systems for TV and Radio. In modern radio and tv systems operating on FM/VHF/UHF you usually have a network of small repeaters covering a small area with relatively low power signals, much like a cellular telephone network. However, in the old days you had truely scary AM and VHF towers that broadcast using brute force technology i.e. just pumping in huge amounts of power from a single site.

Modern technology is probabally a lot healthier.

There are a few things when it comes to cancer risk:

1) Cancer's now being diagnosed more effectively where as decades gone by it was often undetected and the symptoms may have been attributed to something else. So, rates may not be actually rising, but rather detection.

2) We're sorrounded by known carcenogens, yet we choose for whatever reasons to ignore them.

The fundemental people have to get into their heads is that life is carcenogenic generally. And living will lead to your eventual demise!


[This message has been edited by djk (edited 06-27-2005).]
Posted By: pauluk Re: health & high voltage - 06/28/05 01:54 PM
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if you're in a good coverage area your mobile uses far less power to connect to the cell mast!
Maybe we need a campaign to educate people on this subject? How many times have you heard somebody going on about the radiation from the cell-tower, yet not say anything about the field from their own cellphone?

I'm sure you must have tried to explain the inverse-square law too. I've tried dozens of times, but I'm not sure whether I've always been understood or believed.

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However, in the old days you had truely scary AM and VHF towers that broadcast using brute force technology i.e. just pumping in huge amounts of power from a single site.
Back in the early days of TV when the BBC was still broadcasting from the Alexandra Palace transmitter my family lived in a part of North London just up the road. That was before my time, but my parents assured me that they could get a viewable picture with nothing connected to the average set, and an absolutely perfect picture with just a couple of feet of wire hanging out the coax socket. That was Ch. 1,, so fairly low freqencies (~45MHz), but it still must have been a pretty high field strength.

I still remember the announcements from Radio Luxembourg when I used to listen in the early 1980s: "This is RTL Radio Luxembourg on 208 meters, 1440 kilohertz, broadcasting with one million three hundred thousand watts of power!" [Linked Image]

If you lived next door to their AM array I reckon that with suitably placed coils you could get enough free power to light your house! [Linked Image]

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2) We're sorrounded by known carcenogens, yet we choose for whatever reasons to ignore them.
Yep, there is more than one variable in the equation, which makes objective comparisons that much more difficult. Even finding a suitable section of the population to use as the control is going to be tricky.

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And living will lead to your eventual demise!
Hey nobody told me that when I started out on this adventure. I've been conned! It's not fair! [Linked Image]



[This message has been edited by pauluk (edited 06-28-2005).]
Posted By: Trumpy Re: health & high voltage - 06/30/05 01:50 AM
kiwi,
I had the chance to do some "research" of my own yesterday.
I took a Micro-Tesla meter with me and stood under some lines around the district.
(Ok, so I was bored, but it made for interesting readings and some really strange looks from passing motorists) [Linked Image]
All of these tests were taken directly below the lines (ie: in the centre of the two 3-wire circuits on each side of the pylon)
with the meter held at eye level (1.79m):
  • 220kV circuit- Boundary Road: 0.37 uT
  • 110kV circuit- Laghmor Road: 0.52 uT
  • 500kVDC circuit- Cairnbrae: 1.16 uT
  • 66kV (1 circuit)- Pendarves: 0.08 uT
  • 22kV (1 circuit)- Tinwald: 0.021 uT
  • 11kV (1 circuit)- Boundary Road: 0.002 uT
  • 400V- In Town : Too low to measure.

I might add, that these tests were done with a TELARC calibrated meter.
Which raises the question about the meter used in the original documentary, was it in fact accurately calibrated?.
Posted By: mxslick Re: health & high voltage - 06/30/05 03:39 AM
Trumpy:

Very interesting readings. Anyone else notice that the HVDC line has the highest reading? (By a factor of at least two times the AC circuits...)

And the 110kV was the highest of the AC lines (more heavily loaded, perhaps?)

I would not lose any sleep being near the AC lines for sure, not in regards to the EM fields. I'd be much more concerned about the lightshow during an earthquake! (Been through a few, that evil arcing sound always scares me more than the shaking.) [Linked Image]
Posted By: djk Re: health & high voltage - 06/30/05 01:04 PM
Trumpy:

There's a campaign in Germany against powerline internet access as it potentially interferes with shortwave radio.

[Linked Image from delta-oscar-qrp.de]

no e-smog in my home!
Posted By: Trumpy Re: health & high voltage - 07/01/05 10:42 AM
Djk,
E-smog,
Now I am impressed, I've never heard it called that before.
BTW guys, TELARC is a Testing Laboratory here, it has nothing to do with the ISO 9001 Accreditation system touted around the world.
Mxslick,
Yes, there is a bit within the readings, but on the other side of the coin, never has it been stated on any programme that I've ever seen, that the meter used was calibrated to any standard at all.
Which in my own opinion, makes the readings meaningless.
Makes you wonder if the "consultant" didn't buy the meter from a cheap dodgy $5 market place, or the $2 shop.
One other thing, is the fact that, would a reporter actually question the readings, if it sounded good to those watching?.
There is real science and there is the media's take on science.
Don't forget, it's all about ratings these days, not facts. GRRR
[Linked Image]
Posted By: pauluk Re: health & high voltage - 07/02/05 09:53 AM
I've just remembered one other little incident which was on a TV documentary a few years ago.

A family living with HV lines running near the back of their property were concerned about the EM fields (I can't remember the voltage levels, but must have been 132kV or above).

Field strength readings around the house didn't show anything out of the ordinary, except when they reached the head of one of the kid's beds when the strength shot up.

It turned out that the meter was located right on the opposite side of the wall.
Posted By: jooles Re: health & high voltage - 07/03/05 02:43 AM
Pauluk:
http://www.offshore-radio.de/JelleBoonstra/luxembourg.htm

This is a good site about RTL Radio Luxembourg.

I worked and lived in Luxembourg City for a while, and a few times we went up to the town of Echternach in the North of the country, not far from the German border. In fact, that's where I bought the nice old SABA radio I sent in the pictures about.

The road from the capital to Echternach goes past a really amazing set of masts. They include the old RL 208 AM ones, but I don't know if they are still there or not, as this is seven or eight years ago. There are no houses nearby, so power theft is probably not an issue -- it is mostly very atractive woodland out there, and it rather hilly with the masts near the top of the hills.

The web page also shows the rather odd and forbidding-looking RTL tower, which is in the middle of a park in the centre of Luxembourg City, very close to Sq. Winston Churchill and very near the bank where I worked at that time. It is surrounded with a dense thicket of pine trees, which are full of crows. The rest of the park has woodpeckers, which are facinating, but also lots of laurel bushes, which cause bad hayfever, so I didn't like going there much.

My Father used to listen to 208 because of the jazz (he is a musician) and said its pinnacle was in the 1950s/1960s.

I'm not sure what those transmitters are doing now, but not all of them are closed.

j
Posted By: pauluk Re: health & high voltage - 07/03/05 08:38 AM
Thanks Jooles -- Interesting pictures.

Completely off-topic, but I notice in one of the photos of a control desk that they have the BBC-type of PPM. I'd always thought that was a peculiarly British type of level meter.
Posted By: kiwi Re: health & high voltage - 07/03/05 10:10 AM
Nice work Trumpy. Nothing beats doing your own research. Your meter is callibrated by a TELARC accredited laboratory, and I'd assume the meter on the NZ made documentary was callibrated also. "Cheap hardware-store" gaussmeters don't exist do they ?

Your higher reading under the HVDC line is interesting. Maybe the house in the documentary I saw is under an HVDC line.

I also saw a NZ made news article this week that showed the gaussmeter measuring up to 40 micro-teslas next to a microwave oven with a bad door-seal. The program then went on to prove that microwave cooking destroyed much more nutrients in food than boiling or steaming.

This now means that the microwave could be more of a health risk than the hv lines over our heads ! ? ! ?

Hell I just don't know what to be scared of now !

By the way the program I just mentioned also advised against under-bench microwave ovens where they could be positioned next to your reproductive organs whilst you are cooking.

Perhaps my recently patented "Lead Apron" will be in stores sooner than I anticipated !
Posted By: Trumpy Re: health & high voltage - 07/03/05 11:02 AM
kiwi,
I've only ever had the one scare with Cancer and that was having a Melanoma cut out of my back about 6-7 years ago.
Mind you, that was more to do with baking in the sun down at Orari Gorge Station as a young fella, nothing to do with EMF's.
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"Cheap hardware-store" gaussmeters don't exist do they ?
You can buy one these days for $4.93 at XXXXXX XXXXXXXXX.
Just like you can get an expert to tell you what you want to hear, if you pay them enough. [Linked Image]
Kiwi,
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Your higher reading under the HVDC line is interesting. Maybe the house in the documentary I saw is under an HVDC line.
I'd doubt that mate, the South Island>North Island Link is the only DC part of the National Grid here at least as far as I'm aware.
It only runs from Benmore to Haywards Bay at the Southern tip of the North Island.
And even then it's kept right out of the way of people.

{Message edited to remove company name}




[This message has been edited by Trumpy (edited 07-03-2005).]
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