For us, we also do an arrestor before the radio, a gas discharge unit.  We
also use an arrestor before the POE injector and anyplace else a cable
enters a structure or piece of equipment.  We use shielded and flooded Cat5
cable with a static drain wire attached to shielded cat5 connectors and also
grounded.  (The static can give you problems just as much as lighting) For
ground, we "try" to stay away from just wire and use copper strap where we
can.  1.5" to 2".  In a pinch I've cut copper pipe in half to give me the
strap needed.  (Never make any sharp angles with the grounds, lightning
likes to go in a straight line) On our MT boxes, I put a thin copper sheet
on the inside and outside where the gas discharge is inserted and attach a
copper ground terminal to it on the outside and use that to ground to the
structure we are on.  For good measure, I use a lighting rated surge
protector wherever we get commercial power.  20 bucks here from Ace
Hardware.  Says they will pay for up to $50,000 in damages caused by
lightning.  (I always thought, the surge has 6 outlets to plug things in - -
What 6 things could I possibly have that would total $50,000 and if I did,
why would I trust a $20 adapter from Ace Hardware???)   What we do is
probably overkill in our area but we haven't lost a unit yet.  I obviously
modify everything, it's a curse.

The experts in all this are the cellular and broadcast tower people.  Look
around on the methods they use.  Polyphaser is a good place to look for
ideas, http://www.polyphaser.com/  I can't afford much of what they sell but
it's good to see what's out there.






-----Original Message-----
From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On
Behalf Of James McBryan
Sent: Wednesday, September 16, 2009 11:52 PM
To: wireless@wispa.org
Subject: [WISPA] Need Lightning Arrestor Advice

Hello all,

I am part of a group installing a wireless network in rural Honduras  
for a growing educational system with a chapter of Engineers Without  
Borders (http://ewb-usa.org). We are creating a 7 node wireless  
network spanning a 3 mile radius. Since Honduras is very prone to  
rain storms and lightning strikes, we need to protect our equipment  
from the lightning. We plan on doing the following:

1) Place an arrestor between the radio and the antenna
2) Place an arrestor in the POE injector

Some of the following criteria we are thinking:

Amount of lightning strikes: One or Many
Insertion Loss: Small as possbile
Frequency : 2.4-5.8 GHZ

When searching the internet, I see many many types of lightning  
arrestors given my criteria. Does anyone have any recommendations  
through their experience with lightning arrestors? What do you use?

Thanks!
James


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