[TowerTalk] Shielded shack

[Jim Lux]

On 9/27/13 10:51 PM, Grant Saviers wrote:
> If it is lightning protection and not RFI shielding that is desired,
> then what is done for explosive magazines ought to be enough!
> http://www.seftim.fr/publications/DDESB/17-3-LIGHTNING_PROTECTION_FOR_CRITICAL_EXPLOSIVES_OPERATIONS.pdf
> has many references, but there are older documents I've seen in prior
> google searches.  e.g. http://www.apd.army.mil/pdffiles/p385_64.pdf  Or
> standards for protection of petroleum storage facilities.
>

There's also a nice report out from Lawrence Livermore on storage 
shelters for nuclear weapons and high explosives, which includes some 
test data.

But realistically, it doesn't take much to lightning protect a single 
room.  The real challenge is preventing the transient EM field from 
propagating.


> I would also think that foil is a bad choice as a conductor should you
> have a strike when #2 or larger is what is commonly used in large
> structures frequently hit.
>

AWG #2 is used for mechanical ruggedness, not current carrying capacity. 
Lighting strokes are high current, but short duration, so a surprisingly 
small wire will carry the current without melting.

There are very large mechanical forces on the wire from the magnetic 
fields from the stroke current, though.