Re: [Ee] Field mill

Finally found a good youtube on this:  The Weather Channel, Sky on Fire.
It doesnt go into much detail on the rocket facility though.



On Tue, Jun 10, 2025, 4:21 AM David VanHorn <[email protected]> wrote:

> Well, I finally found the odd duck I was looking for.  Pasco scientific,
> PS-3211
>
> It has a 30V bipolar range and communicates by bluetooth by phone app.
>
> About $40 on ebay.
>
>
> On Sat, Jun 7, 2025, 3:56 PM David VanHorn <[email protected]> wrote:
>
>> " 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.
>>> --
>>> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
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>>>
>>
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