Posted by
BiBrun on
URL: https://www.es-forum.com/Multimeter-tp1544795p1544805.html
I know a lot of people do measurements the way Stewart describes, and
it has the advantage of being accurate and reproducible. But,
theoretically,
the number it gives is not relevant, because it measure the change in
AC potential (voltage), not the electric field. And theoretically the field
can be very weak even if the potential is large.
I have done interesting measurements with the same kind of meter and
the same settings, but without a ground wire. Just hold one lead in the
hand, making good contact, and extend the other out away from your
body towards the electric source. The trick is to extend that lead without
holding your hand around it, because that will shield the field. Ideally
it should extend far so there's no effect of your body. In practice make
sure it's a least a few inches. You could put the lead inside a cardboard
tube for example. Or tape it to a chopstick. You'll find that the reading
varies with body stance, etc, but you will be able to detect AC electric
fields more
sensitively than with the basic Trifield meter (which also measures magnetic
fields).
Bill
On 8/17/07, Aline <
[hidden email]> wrote:
>
> Hi Stewart,
>
> Thanks for resending that info. I have been corresponding with
> Michael Neuert and he says the ground lead needs to be connected to
> something that sticks into the earth (which means getting a long wire
> as we are upstairs. Is this what you mean when you say 'goes to
> ground'?
>
> Thanks,
> Aline
>
> Stewart wrote:
>
> Any basic multimeter will do. They are cheap now-a-days, and are easy
> to come by.
>
> I measured up to 3V AC, when standing under distribution lines. (The
> smaller voltage one step above entering your home)
> I can only wonder what voltage would be measured under the Big ones,
> or along the highway.
>
> Back on Dec.26, Stewart wrote:
>
> multimeters are a way to directly measure the effect the 120V AC has
> on any of us.
>
> Start with any basic multimeter.
> Set it to AC Voltage
> Set the range to 2 V AC, or 20 V AC if in an extreme environment.
>
> It is easier with a banana jack and wall plug, available at
> lessemf.com, but I was surprised for the money, there was nothing
> special about the hardware sold. But then, I have a technical
> background, and so can make my own cords and plugs, and already have
> some outlet ground cords around for other shielding solutions.
>
> The Common or Negative/Black jack goes to Ground.
> The Positive/Red jack goes to your skin. Thumb squeezing when holding
> meter is good.
>
> Then walk around, sit down, stand up. See how the voltage changes with
> activity, position, and location. Then hold still so the meter
> settles, to get a useful number.
>
> Also, to take outdoor measurements, I used a long metal rod, (meat or
> compost thermometer), to stick in the ground like a ground rod. Then
> an alligator clip from the rod to the black multimeter probe.
>
> I've noticed the resulting voltage is directly related to the distance
> to power lines. When I walked into the woods, and reached a distance
> of 1000 feet, the voltage went to zero.
>
> Stewart
>
>
>
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