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Trying to buy quality EM meter and need help

  1. Nov 9, 2018 at 8:13 PM #1
    Hi all!

    Not sure if this is the right place but I am having really hard time getting these questions answered in other places as well. I became interested in EM topic when power company decided to build a 2x110kV power line near my house. I would like to approach this problem rationally with measuring tools to determine how far the EM field can reach before it becomes indistinguishable form other present radiation. Upon reading more about it I also became more aware of other source, especially HF ones
    inside my home and cell towers.

    I began to search for a viable measuring tool and quickly realized that I'll need to buy several to cover different frequencies and radiation magnitudes. If I may, I would like to ask everyone here a few questions:

    1. Why do experts recommend measuring RF with a single meter while low frequency radiation is measuring magnetic radiation separated from electrical field?

    2. Am I required to re-certify or re-calibrate my meters every once in a while to assure that the accuracy is still decent? I am afraid that this might prove to be very costly, especially in my country.

    3. Some recommend using body volt meter to measure the electric potential on the body itself? How does it compare with mid tier hand-held meters and how would one compare the measurements from both methods?

    4. I noticed that pricier gauss meters measure magnetic field in all 3 axis, 3d basically. But I couldn't find one that does the same with electrical field. Why is it so and do I even need to measure it in 3d? If I measure in 1 axis, do I need to take 3 measurements and combine them?

    5. What exactly does noise represents on the measurement screen (I noticed HF meters often include signal amplifier but not LF ones)?

    I did email all of these questions to 2 re-sellers and 1 manufacturer and haven't received any replies in days even thou the meters in question were $500-$1000. I hope I can find some answers on this forum:)

    Thank you all for your effort and time.
     
  2. jcsd
  3. Nov 10, 2018 at 2:36 PM #2

    dlgoff

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  4. Nov 10, 2018 at 4:39 PM #3

    davenn

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    how far is near ?


    stuff in your home is going to expose you to much more EM than power lines at a distance or cell towers
    eg ... do you use an electric blanket to heat the bed in the winter time ?


    The 2 links @dlgoff has provided should belay your worries :smile:
     
  5. Nov 10, 2018 at 6:50 PM #4

    jim hardy

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    We had a thread last year about magnetic field from a three phase transmission line.
    I think it might be of help

    here it is
    Ampere's law to calculate the B field from a balanced three-phase system

    I can add an anecdote.
    Recall that tap water is pretty conductive.
    A good friend bought a band new house immediately adjacent a 230 kv power line. His back fence was right at the utility right of way.
    When taking a shower in his upstairs bathroom he noticed a mild electric shock from the water.
    He didn't mind the 'tingling' but his wife put her foot down and insisted he fix it.

    He did measure a few volts between the shower head and drain ..
    We discussed his measurements and decided there was some some sort of AC coupling, probably capacitive, into the water inside his PVC plumbing.
    He notified the builder .
    The builder had several more houses in progress alongside the same power line so wanted to nip that problem in the bud..
    The builder removed the bathroom drywall and wired all the metal wall studs to the earth ground rod at electric service entrance.
    That fixed the "Shocking Shower". But i will never know why.

    Point is
    you might find an E-field that's feel-able as far out as a hundred feet
    and measurable somewhat farther .
    Look at that thread i mentioned above
    for it shows that
    once you're away by a distance of (several X the spacing between the phase wires),
    the individual fields from the three phases very nearly cancel one another
    so your total field drops to nil.

    old jim
     
    Last edited: Nov 10, 2018 at 7:08 PM
  6. Nov 10, 2018 at 8:36 PM #5

    Tom.G

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    Faraday shield comes to mind.
     
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