On Sat, 25 Oct 2003 13:09:02 +0100, The Natural Philosopher
wrote:

nightjar

"DKSanders" wrote in message
...

Hi All,
I have been asked to fit a lightning conductor to a friends house

extension

(a 'tower' like extra floor in the middle of the existing house!). How
should this be done, any special considerations etc, where do you get the
conductor from, do you have to use copper 'tape' like you see coming down
from church spires, does it connect to a normal earth rod?

Any help or advice gratefully appreciated, thanks.


As others have said, it is a job for an expert. FYI, you don't use ordinary
earthing rods, but large plates buried in the ground, and the flat copper
strip is chosen because, for transmitting lightning, surface area is more
important than cross-sectional area.



Yes. I forgot to mention the flat plate in the earth. Or morte likley a
few square meters of wire mesh with a solid plate in the middle

That spreads the charge around a bit and avoids localised hot spots of
high voltage.



I installed one on an explosives store back in the 60s. I used inch by
eighth copper strip and buried it in a loop around the whole building.
Any joins had to be copper riveted and soldered. It must have worked
okay since I never heard of any big bangs there until they shut the
mine in the 90s.



--
Alan G
"The corporate life [of society] must be
subservient to the lives of the parts instead
of the lives of the parts being subservient to
the corporate life."
(Herbert Spencer)