Naked Science Forum
General Science => General Science => Topic started by: LoneWolf on 11/04/2019 17:45:44
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My girlfriend had a health scare last year with cancer. After doing research I decided to put some faraday cloth behind our head board and noticed it removed half of the neighbouring wifi signals. So i bought an emf detector to see what the strength of the radiation is. I put the detector on the cloth and got a reading in the harmful range, so, i got an earthing strap with a crocodile clip and connected the cloth to the plug socket which doubled the reading of the radiation. What is happening here? I would have thought grounding it would suck it away to a reading of zero.
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I decided to put some faraday cloth behind our head board
Why?
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Because emf's cause a chemical response in the body. From 1 mobile phone isn't harmful I know but this stuff is now EVERYWHERE. She takes care of herself better than anyone I know and still she had cancer. So I started researching . . . your body can heal itself quite well from emf radiation but you need to be away from it while you're sleeping.
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Because emf's cause a chemical response in the body.
Nope.
So I started researching
You need to do better research.
There is no scientific link between EMF and cancer.
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Umm like I said I did my research! By 2050 everyone will have suffered from cancer at some time in their life, so that's the environment. So, can you explain to me why grounding my Faraday cloth doubles its harmful radiation?
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So, can you explain to me why grounding my Faraday cloth doubles its harmful radiation?
Best guess is that you set up a resonant system somehow,
By 2050 everyone will have suffered from cancer at some time in their life
Says who?
so that's the environment.
The environment clearly has an effect.
So does increased longevity.
Bu that's no reason to imagine it's anything to do with EMF is it?
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I watched an interview with Barry Trower who worked with emf radiation in the military. He claims there are effects on biology. Today I found a number of podcasts missing from my phone so I redownloaded them, it was about 1GB in total and while they were downloading my arm was tingling. There are effects from microwaves but general science says as long as they don't increase the temperature of the body it should be OK. If my arms tingling it meanselectrical impulses are flowing through my nerves of which I can sense. Dr Karl says its non ironizing radiation but there are other effects which he isn't concerned about. If there are other effects and its EVERYWHERE then reducing your exposure will do no harm if I'm wrong.
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My girlfriend says she sleeps much better since I've put the cloth there. That could be psychosomatic, but if she feels more rested each morning I'm leaving it there. Placebos can have positive effects.
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learly has an effect.
So does increased longevity.
Bu that's no reason to imagine it's anything to do with EMF is it?
I never said it was caused by EMF, its as if you're trying to talk me out of taking health seriously.
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Can you describe a resonant system?
The plug I used was in a 4 gang extension lead. I'm not sure if its a cheap surge protector (its behind the bed so I can't see ATM). Could that be the cause?
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50% of the current western population will get cancer. That is the normal, natural incidence. The reason the apparent incidence is increasing is because we all live long enough to get it, and don't die of anything else apart from heart disease, dementia, or pneumonia.By 2050 the life expectancy of babies born that year will be such that almost all of them will express a cancer and about half will die from it. It is the wages of success, not excess.
If you are worried about mobile phoine EMFs, get rid of the phone. The local field of the phone is orders of magnitude larger than all the other manmade sources that civilians are exposed to, including the repeater masts and wifi boxes that everyone makes a fuss about.
The tingling arm is interesting. Some time ago I chaired a conference on bioeffects of low EMF fields. The only experimental evidence was a squid axon that was stimulated by a mobile phone. It just happened that the axon was a quarter wavelength long and thus resonant!
Not surprising that the military are more concerned with EMF exposure as they work close to radar and very powerful UHF and microwave transmitters, all with big "DO NOT TOUCH" notices, but we are talking kilowatts to megawatts here, not a few microwatts of radio fog or even 5 watts from your beloved handset.
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My girlfriend is 43, I don't consider that to be an old age. What's your problem with me trying to reduce EMF radiation while we're sleeping? Its like you're scared that someone will read this and go mental. It's common sense to reduce anything in your environment that's artificial. Our bodies are designed to cope with some emf from the likes of lightning strikes, granite work tops etc. Most microwaves are on 4 specific wavebands but mostly its 2.4ghz. Just because we can't measure a temperature change doesn't mean its safe. imo. As long as we get restful sleep we should be OK. I'm prepared to be wrong on this because no harm will come from it, but if it is harmful then you risk a premature death. If microwaves are not harmful why do all detectors sound an alarm when the power of the radiation goes above a certain strength?
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For most people, it would make more sense to spend the money on a better diet or something (which would improve health) rather than on stuff that just makes conmen richer.
general science says as long as they don't increase the temperature of the body it should be OK
That's not what science did, is it.
Have you heard of epidemiology?
while they were downloading my arm was tingling.
That could be psychosomatic
It's common sense to reduce anything in your environment that's artificial.
So, no crop protection, no medicine, no cooking of food.
The problem with saying "artificial is bad" is that there's nothing more natural than death.
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Pesticides are carcinogenic, atrizine is horrific. We eat mostly organic food, ATM she is making a toastie with home made bread, organic peanut butter and an organic banana. Our grandparents would call organic food, food! Reducing emfs aren't the only thing we're doing, its a multi pronged approach. filtering water, more excersize etc My girlfriend is a qualified health coach but yet she still developed cancer. So back to my opening post: can someone tell me why grounding a Faraday sheet doubles its harmful radiation?
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She takes care of herself better than anyone I know and still she had cancer.
Cancer gains a foothold due to multiple DNA mutations.
- Every cell in your body suffers about 10,000 DNA mutations per day from normal cellular metabolic processes.
- This is without known carcinogens like radiation from granite, cosmic rays, X-Rays, cigarettes, alcohol or oranges.
- ...Let alone any effect of your microwave or mobile phone, which are consistently categorised as "never demonstrated to be carcinogens".
Healthy life processes produce the conditions for cancer to arise.
- In the end, it is death that stops cancer
See: https://en.wikipedia.org/wiki/DNA_damage_(naturally_occurring)#Types
Can you describe a resonant system?
This is where the inductance and capacitance together oscillate at the frequency of some nearby source of radio frequency energy. This can increase the amplitude of oscillation by a factor of 2-100, at a specific frequency (while reducing the amplitude at all other frequencies).
However, the degree of amplitude increase depends on the "Q-Factor" - effectively whether energy is retained within the resonant system, or leaks out of it.
- High "Q" means high amplitude at one frequency, but only over a very narrow frequency range
- The fact that you were measuring this energy on a meter suggests that a lot of energy was leaking out of the system, so any increase in amplitude would be minimal.
- I think resonance would not be the cause here.
See: https://en.wikipedia.org/wiki/Q_factor
The plug I used was in a 4 gang extension lead.
I hope that you are in a country which has an earth pin on its power socket (If you listen to Dr Karl then you may be in Australia, which does have an earth pin...)
- I hope that you connected it to the right pin, or you may have just electrified the wall!
The power line carries a lot of electrical noise, and so connecting the cloth to the power point may have injected noise into the Faraday shield from the mains.
So i bought an emf detector to see what the strength of the radiation is. I put the detector on the cloth and got a reading in the harmful range
Harmful by whose standards?
- Do they document what standard they are using? Please list it in this thread!
- If you connected the cloth to 240V AC, then that is definitely in the harmful range (hopefully the cloth is insulated!!??)
- Do you know what frequency range the EMF detector operates at? In particular, does it pick up 50/60Hz AC power frequencies?
A Faraday shield will reflect away frequencies whose wavelengths are much smaller than the size of the cloth
- Larger wavelengths will just refract around the cloth
- You have to put the cloth between yourself and the source, otherwise you will just be reflecting the radiation back on yourself
- As you note, sources are all around us
- But as others have noted here, the levels in residences are very low (unless you are actually working on a radio transmitter - one navy vessel I visited had lines painted on the deck around high-powered transmitting antennas, marking out the safe distance from each antenna - usually 1 or 2 meters).
while they were downloading my arm was tingling
If doing a download makes your arm tingle (almost certainly psychosomatic), I suggest leaving the phone on the desk while it does the download.
- And I suggest that you download over WiFi (very low power, range up to 30m) rather than over the mobile network (with a range of over 1km, the power produced by your phone can reach much higher levels).
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Hi, thanks for reply. I'm in the UK so we have the earth pin in the socket. I'm connecting the fabric to earth via a earth plug and wrist strap I have for fixing computers. The 4 gang extension is behind the headboard and its flex runs across the cloth/headboard. I'm wondering if its picking up the emf from the flex. I still don't understand how its increasing the mW of radiation. It goes up to 300mW, the alarm sounds at ~50mW.
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That's a lot of RF radiation. Try switching off your organic computer (especially the display), natural mobile phone, any wireless phones, grass-fed WIFI, vegetarian television, HIFI, any fluorescent or LED lights....in fact anything electrical made since 1960, and see what happens. If it still alarms, pop it inside your hemp microwave (plugged into the wall but switched off!) and see what it measures inside a very good faraday cage.
Cancers can occur at any age, as can being hit by a bus. But obviously the longer you live, the more likely it is that it will happen to you. Whilst 50% of the current population will express a cancer at some time, half of those are either curable or nonfatal. Interestingly, although we make a lot of fuss about breast and cervical cancer, more men die from cancer than women. And although we make a fuss about prostate cancer, far more men die with it than from it.
100 years ago UK life expectancy was 45 years. Thanks to "artificial" food, pharmaceuticals, electromagnetism, diesel fumes, etc., it has almost doubled from what my "natural" grandparents could expect. But because they were exposed to diphtheria, cholera, tetanus, smallpox, measles, mumps, rubella, tuberculosis, adulterated bread and milk, vegetables grown on animal faeces, coal dust, horse sh1t ankle deep in the streets, and a thousand industrial hazards, few of them lived long enough to get cancer. The outside toilet was a good idea, though.
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I haven't visited this site for a couple of years, I didn't realise it was so fascist, a place were you can't have a broader view on a subject than the majority in here. I followed Dr Chris Smith & Dr Karl religiously for years! Everything you have all said has been said by both Dr's, but I'm entitled to go and do wider research by people who say things that go against the mainstream and from there I can make an informed decision.
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i bought an emf detector to see what the strength of the radiation is. I put the detector on the cloth and got a reading in the harmful range, so, i got an earthing strap with a crocodile clip and connected the cloth to the plug socket which doubled the reading of the radiation. What is happening here? I would have thought grounding it would suck it away to a reading of zero.
What kind of instrument did you use to measure the radiation, did it require an electrical connection or not. How are you defining the harmful range. Is the earth point you connected to electrically noisy, can you make another earth point in your house perhaps, to copper plumbing maybe, for the test?
The type of meter and how you connect it, can affect sensitive readings dramatically.
It is unclear in your post if you are trying to detect a radiated EMF from a transmitter mast perhaps, or something putting a high frquency signal on your ground cable. Ground cables have an inductance, which is a high impedance path to high frequency and could cause an elevated reading, for various reasons.
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A curious definition of fascism, which is usually associated with The Old Ways and isn't known for espousing logic or helping people identify sources of RF radiation. Difficult to dismiss guys who know about radar, microwaves, ionising radiation, organic chemistry, epidemiology and longevity statisics, and contribute to all sorts of science discussions, as not having a broad view.
Still, I'm a vegetarian, as was Hitler, so there may be some truth in your assertion. We do tend to get a bit dogmatic, at least.
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Hi, thanks for reply. I'm in the UK so we have the earth pin in the socket. I'm connecting the fabric to earth via a earth plug and wrist strap I have for fixing computers. The 4 gang extension is behind the headboard and its flex runs across the cloth/headboard. I'm wondering if its picking up the emf from the flex. I still don't understand how its increasing the mW of radiation. It goes up to 300mW, the alarm sounds at ~50mW.
Putting aside any possible health effects which may or may not be possible. The earth wire could be where the electrical noise is coming from in your measurements. The earth in the UK runs through your house and possibly to a common earth point in the street. Lots of equipment have switch mode power supplies, which put electrical noise directly on to the common earth. Computers, TV's, etc. The earth connection you are using is most likely the source of your increased readings. ie the increased reading is not coming from the atmosphere its coming from your earth wire. You could try putting an ferrite core in your ground circuit, with your ground cable wrapped a few times around it, that may help reject the noise from the earth. and or connect to the heating system in the house, since you are in the UK assuming it is copper and not plastic plumbing, that may give you a cleaner earth connection
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Best of all, get an "earth rod" from your local builders' merchant, bash it into damp ground, and connect to it with a heavy copper cable. If you live in a flat, particularly over a shop, launderette or cafe, or in a high rise building, you may find anything up to 5 volts AC, at all sorts of frequencies, between the mains earth and the real one.
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The instrument I'm using is a Benetech GM3120. I spent days looking on web search sites looking a good one and this seemed to be the best. I've since found better ones which are in the hundreds of pounds range. The main emfs I'm trying to reduce are neighbouring WiFi signals, putting the cloth there has halfed the number of detectable APs. I'm sure its not very electrically active other than the 4 gang extension and its cable behind the bed. Your reply has been the best by far. Thankyou.
I've just noticed a few other reply's. I get the point about the common earth which I find scary because I use the ground plug while I'm repairing PCBs and building computers, it was what we got taught at night school. Its possible I might be doing more damage by earthing, possibly.
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Like Alan says above an earth rod independent of other electrical equipment would be your best solution.
If you do this you can confirm by measuring between your new earth and your old earth where the signmal is coming from.
A quick look at the meter https://www.testmeter.sg/products/Benetech-GM3120-Electromagnetic-Radiation-Tester/302 its field meter. What you are probably doing via connecting your mains earth cable to your shield is making a little antennae to retransmit the ground noise. Using a ferrite on the earth cable and or as Alan mentions a seperate earth rod should dispense with the induced electrical noise from your earth appearing on your screen.
You dont start physically feeling anything in the atmosphere until the field meters start reading 10000V/m when your fillings tingle. :) Then be very careful what you touch or you will be :o
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Using a ferrite on the earth cable
LOL
Do you realise what effect that would have?
est of all, get an "earth rod" from your local builders' merchant, bash it into damp ground, and connect to it with a heavy copper cable.
This is the equivalent of telling someone which font to use when replying to emails from Nigerian princes who are trying to get their money out of the country and just need to borrow your bank account.
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I was changing the charging port in her HTC phone before so I tested the proper earthing matt in the back room. Disconnected it gave no reading, connecting the earth strap direct to the wall outlet I was getting ~90mV. So it must be the earth in the house. I would have thought that would trip an MCB. I also tested it earth to a copper radiator pipe with the same readings. The grounding spike seems the best solution but getting a cable to downstairs is a pain.
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The grounding spike seems the best solution
Solution to what?
How have you come to the conclusion that there is a problem to solve?
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an organic banana
Bananas (even organic ones) are very high in Potassium, which makes the banana more radioactive than most fruits and vegetables (except maybe Brazil nuts).
See: https://en.wikipedia.org/wiki/Isotopes_of_potassium
It goes up to 300mW, the alarm sounds at ~50mW
Looking up the specifications, it looks like:
Alarm Threshold: electric: 40V / m, magnetic 0.4μT
Test Bandwidth: 5Hz - 3500MHz
This device does not measure milliWatts (mW) but milliVolts per meter (mV/m).
- And the alarm thresholds look very different from what you indicated (maybe I looked at the wrong datasheet?)
So it will be picking up AC mains voltage, which is the highest voltage flowing around your house (around 230V rms 50Hz, in the UK). This will include sources such as wiring in the wall, and the plugpack. Fortunately, if active and neutral are in the same cable (eg 2mm apart), the fields almost cancel out when you are measuring > 10cm away. What does not cancel out is any voltage on the Earth stake.
However, 50Hz has an extremely long wavelength, so it will refract around any sheet you put on your wall.
Fortunately, the coupling into biochemical reactions is effectively nil (unless you connect yourself directly to the mains voltage!).
wrist strap I have for fixing computers
These devices are intended for safely discharging electrostatic fields (which can be in the range of 10kV, or 1 MV/m).
- These discharges can cause cellular damage - to the 0.1mm2 of skin (or even smaller transistors inside a computer chip) which suffers the electrostatic discharge.
- To prevent discharge, they typically include a 1 MOhm or 10 MOhm series resistor.
- This is almost an open circuit compared to the 50-100 Ohms impedance of the cloth picking up radiation from free space.
I suggest that when measuring these fields, you put the wrist strap on yourself, as you are probably measuring electrostatic buildup as you walk across the carpet or slide across bedsheets.
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Cheers Evan_au. It looks like I got bamboozled with the alarm sounding.
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Using a ferrite on the earth cable
LOL
Do you realise what effect that would have?
Yes :) Firstly it would reduce some of the HF electrical noise, which I suspected was coming from the earth cable, reaching the head board and creating the perceived problem, not knowing what kind of instrument was being used. Any 50Hz signal induced by the mains effect would not be affected by a small ferrite. The meter was reading V/unit distance which is affected by how far from the source you are.
Introducing the ferrite might create other harmless electrical effects, do you realize what they might be LOL :)
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Never bath in Irish Stew,
It's the most illogical thing to do,
But should you go against my reasoning,
Don't fail to add the appropriate seasoning !
If you actually plan to do this, the cheapest + most effective approach is to wallpaper the room with aluminium foil. (You can put conventional paper on top if you like.)
You can tell when you have done it properly- because your mobile phone will stop working.
(But don't keep the phone in there with you, it's a radio transmitter and will be blaring out as much radiation as it can in an attempt to get a signal)
By this means you should be able to reduce the RF EM radiation down to levels lower than our elizabethan ancestors were exposed to.
And by your logic, with luck that will increase your life expectancy to that you would have had back then.
Google tells me that's 42 years...
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Thanks for the reply Bored Chemist, brilliant! I recommend a cup of Iyawaska (DMT). If you don't know what this is watch Graham Hancock's banned TED talk.
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And by your logic covering my walls with Aluminium and being 43 I will drop dead because the only the only thing keeping me alive is RF radiation. I've just had a brainwave, we should all move near Chernobyl!
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And by your logic covering my walls with Aluminium and being 43 I will drop dead because the only the only thing keeping me alive is RF radiation. I
No, you made that up, didn't you?
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What your reply was meant to say is 'I'm not allowing you to have the final word'.
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If I had wanted the final word, would I have asked a question?
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Very little RF around Chernobyl, but plenty of healthy wildlife.
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Indeed. Heres a website I sourced some of my knowledge from regarding EFRs
https://bioinitiative.org
This website says there are effects. So minimising rf will do me know harm. Imo
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Very little RF around Chernobyl, but plenty of healthy wildlife.
RF can cause burns but it does not ionize or change your DNA. https://www.cancer.org/cancer/cancer-causes/radiation-exposure/radiofrequency-radiation.html
Every cloud MAYBE has a silver lining http://birdingbelarus.by/tours/chernobyl/?lang=en I wonder if the animals develop tumours from the radioactive radiation in the exclusion zone. http://usukr-env.org/en/the-animals-in-chernobyls-radiation-zones-are-not-thriving-as-some-have-claimed-but-failing/ oops! it seems they might not be being hunted, but they do seem to have problems with tumours etc.
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wallpaper the room with aluminium foil
I have actually done something similar - for thermal insulation purposes, when building a new room, I selected wallboard which has aluminium foil on one side. The wallboard comes in big sheets maybe 2 meters long, and 1.5 meters high, aluminium already attached.
However, I changed mobile phone providers, and this Faraday-enclosed room appears to be between my home office and the nearest mobile base station, so now I get really bad reception in my home office!
The room is not entirely shielded - there are windows, and a wooden floor...
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I wonder if the animals develop tumours from the radioactive radiation in the exclusion zone. http://usukr-env.org/en/the-animals-in-chernobyls-radiation-zones-are-not-thriving-as-some-have-claimed-but-failing/ oops! it seems they might not be being hunted, but they do seem to have problems with tumours etc.
Nothing new there, though the comparison with Fukushima is scientifically disgraceful.
Always worth reading the small print. Yes, animals in the zones of highest activity have the most defects. Just as expected and consistent with laboratory studies and the fact that other animals eat what they find locally whereas humans are likely to reject contaminated food and import clean stuff. There is a huge difference between ingesting long-lived radionuclides, particularly α-emitting "hot particles", and being exposed to external γ radiation
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the comparison with Fukushima is scientifically disgraceful.
Says the man who said "Very little RF around Chernobyl".
It makes no real sense to try to compare RF which does not cause ionisation (and therefore chemical reactions), with nuclear radiation, which is ionising and does cause chemical change.
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The Fukushima radioactivity release was probably 10% or less of that at Chernobyl, with substantially better containment of solid materials, and the resulting exclusion zone appears to be less than 10% of the area of the Chernobyl EZ. Interestingly, it seems that some 1600 people died in the Fukushima evacuation, far more than at Chernobyl (I don't have the figures to hand but IIRC it was less than 50).
On consideration I am inclined to retract "disgraceful" and replace it with "an order of magnitude inappropriate".
It was the original questioner, not I, who implied that RF and nuclear radiation were sufficiently similar that his bedroom was comparable with the suburbs of Chernobyl.
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It was the original questioner, not I, who implied that RF and nuclear radiation were sufficiently similar that his bedroom was comparable with the suburbs of Chernobyl.
I will take your word for it. There's a lot he said where I can't really tell WTF he means.
I had missed this bit earlier
I'm connecting the fabric to earth via a earth plug and wrist strap I have for fixing computers.
It depends where the resistor is, but, if it's near the plug then you have effectively connected an aerial to your cloth.
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You have a space in which there are multiple sources all coming from different directions, they then reflect off anything and everything creating multipath interference. Hanging up your conductive curtain serves to do little other than stir the pot, and reflect the signals in a different pattern. A bit like holding up a mirror in a room full of lamps: as fast as you cast a shadow from one lamp you reflect another.
Your detector won’t show this because it’s not selective, it’s measuring the total field and unable to see what’s going on with each source separately. Imagine a classroom full of schoolkids: it’s bedlam because they’re all sat rabbiting. You wonder where the din is coming from, so you take out a gag and place it on one of the kids. You hear no difference, so you take it off and try the next kid, then the next and the next. By the time you’ve been round the whole class you’ve come to the erroneous conclusion that the noise isn’t coming from any of them. What you need is the ability to listen to each one independently so that you can see what effect you’re having on each source one at a time, and in your room, that’s what a spectrum analyser does: you would see a forest of signals, and when you move the detector, or the large objects in the room, the amplitude of the signals would bounce up and down like yoyos.
Failing that, a gag that fits all the kids at once will do, that’s where the suggestion of aluminium foil on the walls comes in. Your problem though is creating a seal: no window, a continuous connection at the seams (including around the door), a sealed air vent, and last but not least, if you want power in the room you need filtering to stop signals being carried in on the power leads.
Or alternatively, you could just sit and wonder why you’re so bothered about it in the first place.
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CANCER
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Since there is a 50% probability of anyone getting a natural cancer if they live long enough, it's probably not an efficient use of one's life to worry about it.
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Until you get it, which my girlfriend did. Thanks for everyone's input.
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Until you get it, which my girlfriend did. Thanks for everyone's input.
That rather misses the point that whatever caused the cancer almost certainly wasn't anything that a faraday cage would stop.
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Nor would it be any use as a cure. There may be means of treating primary tumors and minimising metastasis, but apart from avoding the obvious carcinogens like smoking and industrial feedstocks, there isn't a lot you can do about cancer except to spot it early and treat it like any other disease when it happens.
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avoding the obvious carcinogens like smoking and industrial feedstocks, drinking alcohol and exposure to sunshine.
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Benzene, toluene and xylene are labelled as carcinogenic, along with blue asbestos, aniline, beryllium, cadmium, dioxane, ethylene bromide.... NIOSH has a complete alphabet of stuff that we use to make other stuff, but prefer to keep inside glass and steel tubing, not becuase it is acutely toxic but is definitely carcinogenic. Fortunately civilians rarely encounter any of them.
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Fortunately civilians rarely encounter any of them.
Which means that, for most people, they are not the "obvious carcinogens".
BTX are carcinogens, but are products, rather than feedstocks. Ditto aniline, dioxane, and dibromoethane.
Blue asbestos is practically banned.
So, you just don't come across them much.
The exceptions are BTX which are present in petrol.
But that's reasonable well controlled and they are poor carcinogens. Most people who use them don't get cancer from them.
Industrial pollution is probably a bigger factor.
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Can I re-ask this question.
I've got a electrostatic matt that I use to ground myself when fixing computers. If I put my tester onto it while it isn't grounded I get a readout of 0mV. When I attach the grounding wire to the earth plug I get a reading of ~80mV. Shouldn't it be the other way around? I asked an electrician who didn't understand it either.
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Fortunately civilians rarely encounter any of them.
Which means that, for most people, they are not the "obvious carcinogens".
BTX are carcinogens, but are products, rather than feedstocks. Ditto aniline, dioxane, and dibromoethane.
Which means that, for most people, they are not the "obvious carcinogens".
BTX are carcinogens, but are products, rather than feedstocks. Ditto aniline, dioxane, and dibromoethane.
Blue asbestos is practically banned.
So, you just don't come across them much.
The exceptions are BTX which are present in petrol.
But that's reasonable well controlled and they are poor carcinogens. Most people who use them don't get cancer from them.
Industrial pollution is probably a bigger factor.
People are very rarely struck by lightning. I think we are arguing about the definition of "obvious"! But it keeps the wits sharp.
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Can I re-ask this question.
I've got a electrostatic matt that I use to ground myself when fixing computers. If I put my tester onto it while it isn't grounded I get a readout of 0mV. When I attach the grounding wire to the earth plug I get a reading of ~80mV. Shouldn't it be the other way around? I asked an electrician who didn't understand it either.
Voltage is always "relative to..." You are trying to measure a potential difference. So the first question is what is the other end of your tester connected to?
Next question is 80 mV AC or DC?
And finally, what is the input impedance of your tester?
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The technical parameters of the detector are as follows:
Unit - V/m
Precision - 1V/m
Range - 1V/m- 1999V/m
Testing bandwidth - 5Hz--3500MHz
Its not connected to anything else, its just face down on the antistatic matt. Ive just tested it and im getting 261V/m
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That's a lot of field strength. Need to think a bit.
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If I put my tester onto it while it isn't grounded I get a readout of 0mV. When I attach the grounding wire to the earth plug I get a reading of ~80mV.
I think you might be measuring 50Hz AC fields?
If the tester box is sitting on the electrostatic mat, the sensor within the box might be (say) 10mm from the electrostatic mat.
- If the mat is disconnected from the earth wire of your house, the mat and the tester will have effectively the same potential, and the reading will be 0 Volts/Meter (there may still be a magnetic field, as I understand it can detect both)
- If the mat is connected to the Earth wire in your house, the mat might carry an AC signal of (say) 2.6 Volts. Correct for the distance to the sensor (1/100 meters) and you could get a reading of 261 Volts/meter.
Precision - 1V/m...
I get a reading of ~80mV.
When you say "Precision", do you mean "Resolution"?
- If the Precision is 1V/m, then 80mV/m +/- 1V/m is still pretty close to zero (but depending on the design, it may still be a useful indication of relative field strength...)
- If the Resolution is 1V/m, then I don't see how it can report 80mV
These definitions can get a bit confusing, and I'm not sure I always get it right: https://en.wikipedia.org/wiki/Accuracy_and_precision
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According to The Control of Electromagnetic Fields at Work Regulations 2016, a 50 Hz field strength exceeding 1.4 V V/m will produce a sensory effect and 170 V/m is an "action level" in the MHz - GHz RF range. Health effects are likely at 10 V/m at low RF frequencies (below 10 MHz) The probability of anyone being exposed at these levels in the home is very low indeed unless they are using a mobile phone.
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Evan_au when I said ~80mV it should have been ~80V/m my mistake. I don't understand what's caused it to jump up to 261V/m. I have juatvdone some problem solving, I left the detector on the matt (it was beeping) and turned the electricity off at the consumer unit and the beeping stopped, the readout was 0V/m. So something is leaking to earth. I have a number of surge protectors, could it be them? Also, if I turn my hot water on (conventional system) the TV downstairs goes off for a second. Wonder if its that.
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Almost certainly a significant "earth" voltage, possibly a wiring fault. Has the property been extended, rewired, or acquired some new high-power kit like a jacuzzi? I recall a client complaining that he felt a "tingle" walking from his swimming pool to his new hot tub: I found the two "earth bonds" to be 50VAC apart.
So back to my earlier suggestion: bash an earth spike into damp soil and measure the voltage between the planet and your mains earth. Should be less than 5V AC or DC. If not, get an electrician to investigate. Likewise, as you now have a long piece of wire, check the voltage and continuity between the earth pins of your mains sockets in adjacent rooms.
Surge protectors and interference suppressors can leak significant current to earth but the bonding between adjacent rooms and from any room or installed device to the incoming main earth reference terminal should be better than 0.2 ohm.
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a 50 Hz field strength exceeding 1.4 V V/m will produce a sensory effect
Is this a typo of some kind?
When I pick up a 1.5V battery across the terminals, I don't feel a tingle - and that is through a 0Ω circuit.
- The reason is that my skin has a breakdown voltage of over 12V (provided I don't have any cuts)
However, 1.4V/m through air has a series impedance of 1 MΩ or so; I don't see how that could produce a "sensory effect"?
- Could you mean 1.4kV/m? (1.4MV/m would have a hair-raising effect, often seen in science museums!)
● the electric field induced inside the body is considerably smaller than the external electric field, e.g., five to six orders of magnitude at 50 – 60 Hz;
● for a given external electric field, the strongest fields are induced when the human body is in perfect contact with the ground through the feet (electrically grounded), and the weakest induced fields are for the body insulated from the ground (in “free space”)
And...
●Thresholds for direct perception by the most sensitive 10% of volunteers at 50 – 60 Hz ranged between 2 and 5 kV/m
●However, peripheral nerve stimulation induced during volunteer exposure to the switched gradient magnetic fields of magnetic resonance (MR) systems suggested that the threshold for perception may be as low as about 2V/m
●The threshold for induced electric field strengths in the retina has been estimated to lie between about 50 and 100
mV/m at 20 Hz
So here we have an enormous range of potential effects....
- For 50Hz electric fields in the home (through air), we are talking about kV/m
- If your home is within the extremely strong magnetic field of an MRI, and subjected to loud audible noises and radio-frequency fields, 2V/m may be detectable
- At the other extreme, your retina (essentially an analogue detector) can be fooled by fields as low as 100mV in the right frequency range (but external electric fields would be attenuated by several orders of magnitude because the retina is within the conductive fluid of your body). Magnetic fields in the mT range can also produce visual effects, and these aren't strongly attenuated by the body.
Overall, external electric field recommendations for public exposure to 50Hz voltages (through air) are < 5kV/m (and higher for workplace exposure)
See: http://www.icnirp.org/cms/upload/publications/ICNIRPLFgdl.pdf
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The reason is that my skin has a breakdown voltage of over 12V
No it hasn't.
A half decent meter will measure the current through your fingers driven by a 1.5 volt battery.
The current voltage curve probably isn't close to linear.
When I pick up a 1.5V battery across the terminals,
Did you see the bit about 50Hz?
Capacitive coupling starts to become important.
At higher frequencies you start acting like a radio antenna.
And that's where those field strengths they quote apply.
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IIRC the IEC 60601 low-frequency model for a human being is 1kΩ in parallel with 1μF with a maximum permissible current of 5 mA from hand to hand. This presumes intimate contact with saline-wet hands (it's the medical equipment safety standard). In my civilian capacity as a double-bass player, however, the skin on my fingers is so hard and dry that I don't always notice 100V DC.
The CEFWR sensory effect ELVs are for electric fields inside the head. Until Alzheimer takes over completely, I think the contents of my skull are a lot more conductive than my fingertips, and my optic nerves are carrying microvolt signals.