Re: [Ee] Field mill

" As a hypothetical, if you lay a 100ft pair of 24AWG wires with 300V
insulation on the ground, and lightning strikes one end, what potential
appears on the other end? The potential is with respect to what? And for
how long does the potential exist? Is it likely and/or possible and/or
desirable for the wire to survive a direct strike at one end of the cable?"

The potential that matters is what ends up across me or my vehicle, or my
equipment.  It lasts some milliseconds.  It's not likely that the field
mill or the wire would survive a direct hit.  20 to 50 kA does interesting
things.
The old trueism that lightning never strikes the same place twice isn't
really true, but frequently it's somewhat true as "the same place" isn't
there anymore. :)

I'd urge you to read up on Charles Steinmentz and everything by Martin Uman.
https://en.wikipedia.org/wiki/Martin_A._Uman

That copper wire MAY perf it's insulation near the tripod and leave me with
only a few hundred volts, or it may become a plasma channel with resistance
of a few ohms leading the bulk of the strike directly to me.
I'm not willing to risk a copper path that leads directly to me.   Even if
only a few hundred volts, it could easily be lethal. It will be rather
humid, and I may well be very wet.
I will also be FAR from any medical support. Heart goes into Vfib and I'm
done.


On Sat, Jun 7, 2025 at 4:02 AM Jason White <
[email protected]> wrote:

> I used to design direct lightning strike circuit protection networks for
> avionics - so I might be biased.
>
> You probably already possess about a dozen ways of getting a reading to you
> safely with stuff you have just laying around.
>
> As a hypothetical, if you lay a 100ft pair of 24AWG wires with 300V
> insulation on the ground, and lightning strikes one end, what potential
> appears on the other end? The potential is with respect to what? And for
> how long does the potential exist? Is it likely and/or possible and/or
> desirable for the wire to survive a direct strike at one end of the cable?
>
> Suppose the end of the cable was attached to an indicator: a $5 meter, or
> LED sting, or whatever. What would it take to render said indicator safe to
> stand next to and look at? Is it possible for the indicator to be usable
> without ever touching it? Is it likely and/or possible and/or desirable for
> the indicator to survive a direct strike at one end of the cable?
>
> I can speculate, but I'd like to hear what you and others think.
>
> I'm genuinely curious about the answers. My intuition tells me one thing,
> but maybe I could be wrong.
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