The surge suppressors will still block transverse impulses but they will not be
able to recognize longitudinal (common mode) impulses without a ground. Isn’t
there a lightening rod or obstruction light up there that you could ground to?
From: Josh Baird
Sent: Wednesday, September 30, 2015 9:11 AM
To: af@afmug.com
Subject: Re: [AFMUG] Grounding strategies for water tanks
Ok, so I have a little more information now.
The city that owns these tanks forbids us to mount /anything/ directly to the
tank it's self. They also forbid us to scrape any paint to ground anything.
There is a thick rubber guard that covers the rails where the antennas are
mounted. The antennas are mounted on top of this rubber guard (not directly to
the metal). The antennas will have short CAT-5 runs to a tower-top box, and
then fiber/DC down the tower to our battery/charger.
In this scenario, should we just try to make sure everything is isolated from
the tank as much as possible and float the ground? I was planning on using
GigEAPC-HV surge protectors at the top for all of the radios. If the surge
protectors are not grounded, is there any point in even using them seeing that
they won't have any ground to discharge the surge to? Will they provide any
benefit at all? I was also planning on using DC surge suppressors between the
DC cable that runs up the tank (one at the bottom, one at the top). Again,
will they be useful at all if we are floating the ground?
Thanks,
Josh
On Mon, Sep 28, 2015 at 12:46 PM, Mark Radabaugh <m...@amplex.net> wrote:
We have had pretty good luck with that style of tank.
As to the question - we bonded the #6 to the steel railing and mounting
points at the top, the ladders on the way down, the tank ‘waist’ railing, the
inside ladder, the electrical ground, our cabinet and the associated surge
suppressors, and the steel water line entering the ground.
Mark
On Sep 28, 2015, at 10:38 AM, Josh Baird <joshba...@gmail.com> wrote:
The tanks are like these:
http://www.mscivilengineers.com/images/12.jpg
I'm not sure what the bottom looks like, though. I'll have to go out and
check them. So, you ran #6 all the way down the tank and bonded it inside of
your enclosure/cabinet/whatever?
On Mon, Sep 28, 2015 at 10:31 AM, Mark Radabaugh <m...@amplex.net> wrote:
What type of tank?
The hydropillar and waterspherioid style are generally well grounded.
I have seen some of the steel tank on a concrete pedestal style where the
tank is not directly grounded to the pedestal but has a ‘spark gap’ between the
tank and the base. I’m not sure if the purpose was to distribute the strike
around the tank into the rebar in the column, or if it was an attempt to
isolate the steel for corrosion reasons. The tank we are on like that
consistently has the most lightning damage. I eventually ran a #6 copper from
the top of the tank to the railing and down inside to tie everything together.
It’s improved the situation considerably but it’s still not perfect.
Mark Radabaugh
Amplex
27800 Lemoyne, Ste F
Millbury, OH 43447
419-837-5015 x1021
m...@amplex.net
On Sep 28, 2015, at 10:19 AM, Adam Moffett <dmmoff...@gmail.com> wrote:
Yeah, I would think the tank itself is ground.
On 9/28/2015 10:16 AM, Chuck McCown wrote:
Common point grounding at the power ground would be the NEC answer.
I would do that for power grounds and surge suppressor grounds
because most surges come via the power lines.
For antenna mounting grounds etc, I would make sure they were in good
contact (bonded, perhaps with a separate bonding wire) to the tank or railing
or whatever metal structure you are attaching to.
From: Josh Baird
Sent: Monday, September 28, 2015 8:13 AM
To: af@afmug.com
Subject: [AFMUG] Grounding strategies for water tanks
We are going to be installing on several water tanks that do not have
any other carriers on them. I'm assuming there is probably not a ground ring
or system in place at these sites. The electrical service is likely grounded
independently using a ground rod at the pole.
These sites will have batteries and a charger at the bottom and
fiber/DC up the tower. Admittingly, I'm fairly (ok, very) stupid when it comes
to grounding systems. I understand that everything *should* be bonded
together. However, if the tank it's self doesn't have a sufficient grounding
system already in place, what is the best strategy here?
Thanks,
Josh
