On my first tower we ran a 10ft section of conduit at the top as lightning rod
with a number 4 or 6 copper wire from the ground rod all the way to the top.
It is the highest point on my tower. The only time lightning has been an issue
here it hit a tree nearby and came in through the buried cable.
We also have a piece of copper wire run up the side of each omni sticking about
3 inches above the top.
----- Original Message -----
From: Edward Brooks
To: af@afmug.com
Sent: Wednesday, June 03, 2015 5:24 PM
Subject: [AFMUG] Static & Nearby Lightning Issues
Here goes...
We have a new 118' Super Titan Max tower that has been grounded per
manufacturers recommendations. Each leg is physically bonded (not
exothermically) to a 10' ground rod, all ground rods are then connected to each
other in a ring. The equipment cabinet is bonded to an 8' ground rod and tied
into the meter base grounding as well. The two ground rings are then bonded to
each other in 2 separate places.
With that said our issue has not been with the grounding, but with the
dissipation of static at the height of the antennas. We currently have had the
worst problems with the 3 Cyclone 2.4 antennas which are currently located on
masts at the top of the tower. We have also had issues with a couple of the
5.7 Cyclones located below the top of the tower, but not as frequently. The
center-line of the 2.4 APs is 120' AGL, the height of the tower is 118' AGL.
We currently have WB-GigE-APC surge arrestors located in the cabinet which is
located 10 ft from the base of the tower.
After doing some research through various Cambium manuals and the
Motorola R56 manual, I have some idea what our issue is, but would like to
bounce those ideas off the community. My thought is that we neglected to put
surge arrestors at 50' to 75' intervals (as recommended by the Motorola R56
manual) and 1 at the top for use in thunderstorm areas. Also we may need to
lower the APs to a minimum of 2ft below the top of the tower (per the Cambium
manuals for various antenna types).
Any suggestions or comments would be appreciated. What have you done to
mitigate this problem? Etc...
Thanks,
-Ed
--
Edward Brooks
Outside Plant Manager
The Montana Internet Corporation
406-443-3347 X506
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