Re: [TCML] comments on designing a lightning protection system

["Mike H" <mike8675309@xxxxxxxxx>]

On Mon, Jun 9, 2008 at 9:42 PM,  <FIFTYGUY@xxxxxxx> wrote:
...

> defined. How can you engineer a lightning protection  system if you don't define the
> parameters of lightning? It would seem that a  truly professional installation
> would include statistical data about  historical lightning in the area, and
> what level of lightning the system would  be designed to protect against (to
> what degree). How do the contracts  read?
...

I believe the whole catch in lightning protection is that there isn't
complete data to engineer against.  Certainly information today is
much greater than has been known in the past.  Yet trying to find
information on the Internet is difficult as the internet is full of
scams, and outdated information.

This page.. on it's surface appears to have some information you are
looking for.  Though I haven't reviewed it fully.
http://www.lightningsafety.com/nlsi_lhm.html
for example:
The Lightning Attachment Process and Risk Management of the Hazard
  By Richard Kithil Jr., Founder & CEO, and Richard Hasbouck, Consultant
-Introduction
When lightning strikes at or near a critical or high-value facility,
stroke currents will divide up among all parallel conductive paths
between the attachment point(s) and earth. Division of current will be
inversely proportional to the path impedance Z (Z = R + XL, resistance
plus inductive reactance). The resistance term will be very low,
assuming effectively bonded metallic conductors. The inductance and
corresponding related inductive reactance presented to the total
return current will be determined by the combination of all the
individual inductive paths in parallel—the more parallel paths, the
lower the total impedance.

-Transfer Impedance and the Earth Electrode Subsystem (EES)
Lightning can be considered as a current source, i.e., output current
is independent of load impedance. A given stroke will contain a
certain amount of charge (coulombs = amps x seconds) that must be
neutralized during the discharge process. If the return stroke is 50
kA, then that is the magnitude of current that will flow, whether it
flows through one ohm or 1,000 ohms. Therefore, achieving the lowest
possible path impedance serves to minimize the transient voltage
developed across the path through which the current is flowing [e(t) =
I(t)R + L di/dt)]. Path impedance is directly related to lightning
frequency. Efficiency, in part, is a function of EES volume and
direction (see IEEE 1100-2005, section 4.8 for further details). Field
experience, verified by Finite Difference Time Domain analysis, shows
the application of ring electrodes augmented by radial electrodes to
have significant advantage over ordinary rod electrodes.


> Well, the "copper.org" people would certainly  advocate copper conductors...
> Mentions that hollow braided copper cable.  Wonder if that stuff would be
> suitable for monster TC primaries. Maybe a bit  hard to tap!
>
>>Interesting look at grounding from a HAM  perspective.
>>http://www.astrosurf.com/luxorion/qsl-lightning-protection.htm

>
> I'm glad I'm not a HAM - protecting those  lightning-magnets looks like a
> real pain!
>    Copper ribbon seems to be popular.


I'm pretty sure that nearly everyone advocates copper conductors for
high frequency energy transmission.
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