>From my experience of 30+ years in the 2way radio/paging industry, you are
on the right track putting the ground wire to the top of the tower. I
suspect rusty joints more than the paint. Check out "Cadweld" at your
electrical distributor. This is a means of attaching the ground wires to
your ground rods that won't corrode over time. You can bury the ground rods
completely this way and not be a trip hazard. We install #2 stranded copper
wire to the top of many of our towers for this same purpose and have not had
a problem since.
Maybe you are already doing this, but a coax surge suppressor at the radio
box entrance/exit is good, plus a good quality AC line protector and a cat5
protector. Basically every in/out of the equipment box should have some
measure of protection. If every piece of equipment is bonded to each other,
when a lightning surge happens, every piece of equipment will raise and fall
with the surge voltage. If there is no difference in potential between
devices, there cannot be any current flow between them. No current flow, no
damage.
Steve Loomis
Vroomwireless Inc.
Stillwater, OK
----- Original Message -----
From: "LaRoy McCann" <lmccann@roachconveyors.com>
To: "Karlnet Mailing List" <karlnet@WISPNotes.com>
Sent: Thursday, September 23, 2004 9:42 AM
Subject: [Karlnet] lightening strikes 3 times !!!
> To all,
>
> I have one location where I have had a board zapped 3 times by
> lightening. It is on a 100 ft tower with a 24db grid antenna. Both the
> grid and antenna are mounted about 2 ft from the top of the tower. The
> antenna has a lightening arrestor on it. The tower was orginally grounded
> with a single ground rod. The guy cables anchor with earth screws like
the
> power company uses. The board is mounted in an aluminum box. Cat5 cable
> down into the house.
>
> After replacing the board the 2nd time I added 2 additional ground rods to
> the tower.
>
> Boom, crack, popped again!
>
> It never harms the radio card, only the board. So it has to be coming in
> from the ground side. It never damaged anything else until this last time
> and it also got the guys switch.
>
> I did notice the last time it climbed the tower that it appears that
> someone had painted the tower with a silver paint. I don't know if it was
> done before of after the tower was put up. The tower was already up when
> the current owner bought the house.
>
> My thinking is that the paint may be keeping it from conducting thru the
> joints of the tower. Taking the path of least resistance, it goes thru
the
> board, down the cat5 to a ground some where in the house. Normally the
> guywires will take most of the lightening to ground, but the paint is
> probably preventing that. I plan on running a separate ground wire from
> the ground clamps at the tower base up to the top of the tower and
> terminate it to the aluminum box.
>
> I also have 2 other installations within 7 to 10 miles from this area,
both
> on 100ft towers, and no problems at all. (knock on wood) One of these
> sites is on a tall hill where they took a lightening strike that wiped out
> other electronics such as copiers and computers, but it did nothing to the
> wireless.
>
> Has anyone else had anything similar happen to them?
>
> Thanks,
> LaRoy
>
> _______________________________________________
> Karlnet mailing list
> Karlnet@WISPNotes.com
> http://lists.wispnotes.com/mailman/listinfo/karlnet
>
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