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A popular woodworking magazine published a letter a few months ago from a guy whose doctor said he could no longer use his woodworking machinery because of his pacemaker.  If that was me, I don’t know if I’d take that advice sitting down — I’d probably try to measure the fields with a meter like this one from AlphaLab to see if there actually was a danger or if I could shield the machinery somehow.

Made in the USA, AlphaLab’s TriField meter measures magnetic, electric, and radio/microwave field strength continuously on its analog meter.  The device is sensitive to electric and magnetic fields regardless of orientation because it uses three mutually perpendicular coils in AlphaLab’s unique network configuration.  The included 9V battery lasts for about ten hours of continuous use.

Look to pay about $130 for the meter.

TriField Meter [AlphaLab]
Street Pricing [Google]
Via Amazon [What’s This?]

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11 Responses to Measure The Invisible

  1. Dave says:

    I’m pretty sure there would be no issue whatsoever with being near electric motors. Maybe one from 1930 or so might have a bit of a magnetic field leak…

    They are not even sure if arc welding would cause an issue (radio emissions and magnetic emissions from that).


  2. CN says:

    Funny, I just ran across an article today from the Health Physics Society, a group “whose members specialize in occupational and environmental radiation safety.”


    It says that microwave “leakage is not considered to be a realistic concern” for pacemaker users unless the microwave case is actually damaged. It also gives the maximum allowed radiation the US FDA allows outside a microwave ( 5 mW cm^(–2) at 5 cm), in case the woodworker catches this article, and wants to compare his workshop’s radiation to that of his microwave!

  3. Stan says:

    I think I’d take the buck thirty buy some more tools, and get a 2nd opinion from a Dr. that knows something about Woodworking tools.
    I can’t imagine a single WW tool that could put out a big enough EMF to interfere with a pacemaker.

  4. Leaf says:

    sort of related to this, a cabinet maker told me he didn’t like using the rare earth magnets for catches and stuff because they could interfere with pacemakers. Sounds kind of far fetched to me but I don’t really know anything about pacemakers.

  5. paganwonder says:

    Physician insurance companies have more to do with healthcare advice and choices than science does. The insurance company tells your physician what advice and guidance give you, and insurance companies take absolutely NO chances. I will do my own research thank you.

  6. Keith says:

    I agree with the other posters in that I wouldn’t expect the amount of
    magnetic leakage from most modern shop machine motors to be a problem
    for a decently designed and installed pacemaker.

    Magnetic leakage from a motor means a loss of efficiency, so I would
    expect most of the magnetic flux to be kept within the iron of the motor.

    Also, if the equipment is properly wired (all phases, neutral and ground
    run to a piece of equipment in the same cable) and properly grounded,
    the fields resulting from the power feed to the equipment while it is
    operating should be minimized.

    The exceptions to these statements would be any sort of arc welding, or
    perhaps some older equipment containing an old AC/DC universal motor.

    The old AC/DC universal motors were really DC motors (with brushes and
    a commutator) with the brush angle set at a compromise between that
    needed for DC and that needed for AC.

    Those universal motors tend to produce a higher amount of arcing then do
    other types of motors, such as a pure DC motor or an AC induction motor.

    If you’re just interested on looking around for electric, magnetic, or
    electromagnetic (RF) fields, here’s a less expensive (but not as
    precisely calibrated) alternative to AlphaLab’s unit – if you’re up to
    doing some soldering and assembly work:

    Ramsey Electronics TFM3C – Tri-Field Meter Kit

    Ramsey offers the kit for $64.95 plus shipping and handling.

  7. Zathrus says:


    Microwave radiation isn’t the issue here — it’s concern about the magnetic field. Any microwave radiation that would be strong enough to affect a pacemaker would also cook your heart/lungs/other body parts.


    That cabinet maker doesn’t know the first thing about magnetic fields. That’s really all there is to it.

    Really agree with the others here — I doubt there would be enough of a field to be problematic unless something is seriously messed up.

  8. Chris says:

    I just had to wade into this as a certified engineering technologist (electronics), its doubtful the good doctor is doing snything more than a bit of CYA. Of course I live in Canada and I assume this guy was posting from the US so I cant somment on what its like where he is as far as the medical comunity goes. Having said that , it seems odd that such attention was given to motors. I wonder if this guy has an electric stove as its way worse than any motor for spewing out electromagnetic fields, also these fields diminish in strength by the square of the distance (ie twice as far results in one quarter the strength).

  9. Chris says:

    Not to mention alot of switching devices like thyristors (think of the TRIAC in your light dimmer) create a lot of rf especially if set to turn off at the “right” part of the sine wave ( the dimming effect is caused by the device conducting for only part of the cycle).

  10. Throw in a Geiger counter and this would be awesome.

  11. Bill says:

    It’s possible we’re missing the boat here. The Physician may be saying you shouldn;t work with ANY power equipment, including driving, because of his general cardiac condition. It may be he’s had episodes of fainting etc that necessitated the pacemaker. It may be an implanted defibrillator not a pacemaker, when those things fire the patient tends to get a big enough jolt that they dont want to be near spinning sharp potential implements of destruction when they do fire.

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