Hello Chris,
Yes I could with the cravat that you MUST provide a low impedance ground path
to building ground and a lightning ground system.This path must be direct as
possible and all bends radiused with at least a 6" radius. Roof installations
are particularly hard to protect without a much larger expenditure for funds in
copper! Roof cell sites are usually fed with a 4/0 cu wire to a ground grid at
earth level. That being said you have to live with what you have sometimes.
With a reasonable ground a device similar to the Nott Ltd. GS-1
(nottltd.com/lightning .html), Ericson Broadcast Sales SC-1 or SC-3(or several
SC-3's)
(ebsradio.com/lightning.html) or home built like here:porcupine.w4zt.com will
reduce your strike chance by 95% or so. The last 5% is due to the fact that
sometimes the charge builds up faster than can be bled off with the discharge
array you have. I have also built devices by using 3/8 to 1/2 inch stainless
steel cable one foot long in a compression one hole lug connector (or crimp if
you have access to large enough crimper) on a U-bolt with galvanized or ss
saddle on the tower leg. You fray out the cable to create the largest area of
points you can. Which ever one you choose, try to place it higher than all
antennae. If you must use a rotating member to do this , use a #6 or better
insulated wire to the device and to the nearest tower leg with minimum for
rotation. Similar metal clamps always.
Of course YMMV
Good Luck,
Nick WB7PEK
Christopher J Galbraith <cgalbrai@umich.edu> wrote:
Hi Nick,
Could you recommend a particular lightning discharge device? The
application is a 40 ft tower on top of a 50 ft building in a relatively
lightning prone area (SE Michigan).
Thanks and 73,
Chris KA8WFC
-----Original Message-----
(snip)
If you lived in a more lightning prone area I'd recommend a lightning
discharge device for the tower top. They do a good job of keeping the tower
potential below where a leader arc can be created preventing a strike from
occurring to the tower and a radius equal to the height around it.
Nick WB7PEK
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