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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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Electromagnetic field and medium voltage power line.
I hope that this question is appropriate for this group. I was advised
by a colleague that many of the group regular members were well-informed. I have site that has a medium voltage powerline crossing it. I am engaged in a dispute with the power utility to get the line relocated. It would bolster my argument if I could show that the electromagnetic field (EMF) levels were above a certain level. I know the voltage level and current in amps of the line. Does anybody know how to: 1. Calculate or estimate EMF at a given distance from the powerline with data described. 2. Or where I might find on the Web a site that contains table with precalculated EMF and electric field values for different line types. I think these are called wire codes in the trade but googling has produced little of use - I need at this stage expert or experienced recommendation! Many Thanks Martin |
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Electromagnetic field and medium voltage power line.
"Martin H. Robinson" wrote in message om... I hope that this question is appropriate for this group. I was advised by a colleague that many of the group regular members were well-informed. I have site that has a medium voltage powerline crossing it. I am engaged in a dispute with the power utility to get the line relocated. It would bolster my argument if I could show that the electromagnetic field (EMF) levels were above a certain level. I know the voltage level and current in amps of the line. Does anybody know how to: 1. Calculate or estimate EMF at a given distance from the powerline with data described. 2. Or where I might find on the Web a site that contains table with precalculated EMF and electric field values for different line types. I think these are called wire codes in the trade but googling has produced little of use - I need at this stage expert or experienced recommendation! Many Thanks Martin Buy or hire an emf meter. I hired one as I was concerned about high levels in my house. I also walked across a local field with power wires across it, the readings at head height were off the scale. In my house my sons room had a bad area right where he slept. I think I hired from healthy house. These people hire all sorts: http://www.powerwatch.org.uk/sales/equipx.htm MrCheerful |
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Electromagnetic field and medium voltage power line.
MrCheerful wrote:
Buy or hire an emf meter. I hired one as I was concerned about high levels in my house. I also walked across a local field with power wires across it, the readings at head height were off the scale. In my house my sons room had a bad area right where he slept. I would like to see a certificate of calibration from an ACAS registered standards lab before I trusted a meter to tell me anything. What is "bad" ? What is "off the scale" nV/m ? V/m If I remember the thrust of some of the recent "research" it is LOW fields that cause more problems (if they do) than High fields Steve |
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Electromagnetic field and medium voltage power line.
"Steve" wrote in message ... MrCheerful wrote: Buy or hire an emf meter. I hired one as I was concerned about high levels in my house. I also walked across a local field with power wires across it, the readings at head height were off the scale. In my house my sons room had a bad area right where he slept. I would like to see a certificate of calibration from an ACAS registered standards lab before I trusted a meter to tell me anything. What is "bad" ? What is "off the scale" nV/m ? V/m If I remember the thrust of some of the recent "research" it is LOW fields that cause more problems (if they do) than High fields Steve The meter and research on the net gave some suggested figures that were the maximum to be exposed to. I cannot remember the precise figures that I got, suffice it to say that the only household problem place was my son's room and this was caused by the water pipes under the floor acting as some form of radiating antenna, near which was a very high field. I mention the power lines as an interesting show of the variations the meter would show. The figures indoors where bad were hundreds of times less than below the power lines. I am certain that for a court case it would need a calibrated machine with an expert witness, but I don't believe that is what the OP needs at present. MrCheerful |
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Electromagnetic field and medium voltage power line.
MrCheerful wrote:
The meter and research on the net gave some suggested figures that were the maximum to be exposed to. The problem is any figures will be based entirely on guesswork - there simply hasn't ever been any evidence that exposure to such fields causes any harm, and without such data any figures are meaningless. -- Grunff |
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Electromagnetic field and medium voltage power line.
"Steve" wrote in message
... What is "bad" ? What is "off the scale" nV/m ? V/m If I remember the thrust of some of the recent "research" it is LOW fields that cause more problems (if they do) than High fields I remember hearing a paper by an Oxford academic making this very point - probably about 8 years ago. Something to do with chemical free-radical generation at these lower levels. -- M Stewart Milton Keynes, UK www.megalith.freeserve.co.uk/oddimage.htm http://myweb.tiscali.co.uk/ms1938/ |
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Electromagnetic field and medium voltage power line.
On 10/02/2004 Martin H. Robinson a wrote :
I hope that this question is appropriate for this group. I was advised by a colleague that many of the group regular members were well-informed. I have site that has a medium voltage powerline crossing it. I am not suggesting it is inappropriate for this group, but if you want expert advice on this, then repost your question in alt.engineering.electrical -- Regards, Harry (M1BYT) (L) http://www.ukradioamateur.org |
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Electromagnetic field and medium voltage power line.
In article , Harry
Bloomfield writes On 10/02/2004 Martin H. Robinson a wrote : I hope that this question is appropriate for this group. I was advised by a colleague that many of the group regular members were well-informed. I have site that has a medium voltage powerline crossing it. I am not suggesting it is inappropriate for this group, but if you want expert advice on this, then repost your question in alt.engineering.electrical Where you'll probably get quite a range of opinions too!. IMHO there is, like mobile phone radiation, a lot of research needing doing into these effects, but I suspect that its not going to make a lot of moolah for anyone so it isn't a real high priority as such. I have heard of an anecdotal tale of a number of people who got various cancers who lived in a house near here that is directly under twin 33 KV overhead lines. The current incumbent is a university biological researcher who seems unfazed by his surroundings, and likes the peace and quiet in his location, except for damp foggy nights when the wires hum and fizz quite a bit!...... -- Tony Sayer |
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Electromagnetic field and medium voltage power line.
The Lord alerted my mind to the presence of this EVIL article by Harry
Bloomfield, and I thusly replied: On 10/02/2004 Martin H. Robinson a wrote : I hope that this question is appropriate for this group. I was advised by a colleague that many of the group regular members were well-informed. I have site that has a medium voltage powerline crossing it. I am not suggesting it is inappropriate for this group, but if you want expert advice on this, then repost your question in alt.engineering.electrical Who died and made you Queen? -- The Reverend Parson Peter Parsnip Smiting Sinful Usenet Users Since 1874 "A ******* shall not enter into the congregation of the Lord; even to his tenth generation shall he not enter into the congregation of the Lord." - Deuteronomy 23:2 |
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Electromagnetic field and medium voltage power line.
Hi,
If it is that important to you to get the power line relocated then have you tried asking the power company what they would charge to do the job?. (I am assuming you have been trying to get them to do it at their expense - sorry if I am wrong) Maybe if you were to pay, they would be happy to do it and it may be cheaper than taking the legal route. You say it is a "site" so I am guessing you have bought (cheap?) land where the line was already present. If so, I think you have no chance of getting them to move it at their cost. I got the overhead lines into my house (only 240V) put underground. I dug the trench and they supplied/fitted the cable. It only cost me £125 - bargain - although medium voltage would undoubtedly cost a lot more but may still be a bargain if it makes your site a great one. Costs nothing to find out. Let us all know what they say. Alan. (Martin H. Robinson) wrote in message . com... I hope that this question is appropriate for this group. I was advised by a colleague that many of the group regular members were well-informed. I have site that has a medium voltage powerline crossing it. I am engaged in a dispute with the power utility to get the line relocated. It would bolster my argument if I could show that the electromagnetic field (EMF) levels were above a certain level. I know the voltage level and current in amps of the line. Does anybody know how to: 1. Calculate or estimate EMF at a given distance from the powerline with data described. 2. Or where I might find on the Web a site that contains table with precalculated EMF and electric field values for different line types. I think these are called wire codes in the trade but googling has produced little of use - I need at this stage expert or experienced recommendation! Many Thanks Martin |
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Electromagnetic field and medium voltage power line.
Just as a follow up I discovered a good resource that might be useful
to others. National Grid, the UK power infrastructure company, maintains a website about EMFs at www.emfs.info . Amazingly, given the business that National Grid are in, it seems to be reasonable enough summary of the current debate about the potential dangers of EMFs, an explanation of EMFs and a wide range of links to interested parties including groups and people who clearly are not lackies or dupes of the electricity industry. It is about the best resource that I've seen so far. regards Martin (Alan Campbell) wrote in message . com... Hi, If it is that important to you to get the power line relocated then have you tried asking the power company what they would charge to do the job?. (I am assuming you have been trying to get them to do it at their expense - sorry if I am wrong) Maybe if you were to pay, they would be happy to do it and it may be cheaper than taking the legal route. You say it is a "site" so I am guessing you have bought (cheap?) land where the line was already present. If so, I think you have no chance of getting them to move it at their cost. I got the overhead lines into my house (only 240V) put underground. I dug the trench and they supplied/fitted the cable. It only cost me £125 - bargain - although medium voltage would undoubtedly cost a lot more but may still be a bargain if it makes your site a great one. Costs nothing to find out. Let us all know what they say. Alan. (Martin H. Robinson) wrote in message . com... I hope that this question is appropriate for this group. I was advised by a colleague that many of the group regular members were well-informed. I have site that has a medium voltage powerline crossing it. I am engaged in a dispute with the power utility to get the line relocated. It would bolster my argument if I could show that the electromagnetic field (EMF) levels were above a certain level. I know the voltage level and current in amps of the line. Does anybody know how to: 1. Calculate or estimate EMF at a given distance from the powerline with data described. 2. Or where I might find on the Web a site that contains table with precalculated EMF and electric field values for different line types. I think these are called wire codes in the trade but googling has produced little of use - I need at this stage expert or experienced recommendation! Many Thanks Martin |
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Electromagnetic field and medium voltage power line.
National Grid, the UK power infrastructure company, maintains a
website about EMFs at www.emfs.info I`ll check that one out myself - but the point that all the nay-sayers forget about - if you want electric, cables are required - it doesn`t get around by telepathy. I haven`t seen many of these activists wanting to get rid of all their electric and go back to using gas lamps. As far as EMFs go, you also have to consider "self-inflicted" magnetic fields - of which many you will come into far closer contact with on a regular basis. You can think of your own, but here are few to start you off... VDU / TV electric blanket hair dryer -- Please add "[newsgroup]" in the subject of any personal replies via email * old email address "btiruseless" abandoned due to worm-generated spam * --- My new email address has "ngspamtrap" & @btinternet.com in it ;-) --- |
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Electromagnetic field and medium voltage power line.
See answers embedded below.....
"Martin H. Robinson" wrote in message om... ....snipped I have site that has a medium voltage powerline crossing it. I am engaged in a dispute with the power utility to get the line relocated. ....it would be easier to give a relevant answer if we knew what the motivation was (aesthetic, interference/EMC, EM exposure, (or ???) and whether it's the electric or magnetic field that you're interested in. Does anybody know how to: 1. Calculate or estimate EMF at a given distance from the powerline with data described. ....it's easy enough to calculate for single phase (you need to know the wire separation, height and current) but harder for 3-phase (need to know the phase sequencing on the wires) and harder still for dual 3-phase - overall it's probably easier to measure. A 3-axis magnetometer will give you the magnetic field, the E-field can be estimated if you know the line voltage. 2. Or where I might find on the Web a site that contains table with precalculated EMF and electric field values for different line types. ....typically between 5 and 100 microTesla except under fault conditions, e-field depends on line voltage and height. If your interest is driven by EM exposure considerations these levels are way below the exposure guidelines. If you want more info on this there are a variety of sites: World Health Organisation EMF Project site (loads of authoritative info), UK National Radiological Protection Board (recently published a review of research and concluded no proven risk), International Council for Non-Ionising Radiation Protection (ICNIRP) and so on. If you search on "EC recommendation 519" you'll find a huge amount of info. The bottom line is that there's been a phenomenal amount of research in this area and the only proven and acknowledged effects are nerve stimulation at low frequencies and thermal effects at higher frequencies. It's possible to find loads of sensational scare stories but there is NO independently replicated and peer-reviewed science that supports them (stands back and waits for tidal wave). ....if your motivation is interference or EMC - the only common equipment that's affected by this level of B field are CRT-based VDUs (anything above 0.5 to 1.0 microTesla will cause perceptible jitter. Very little is affected by LF e-fields but ground shift (especially after a line fault) may cause damage if you have multiple ground reference points. Many Thanks Martin ....hope this helps Dave S |
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