R56 methods seem to help.
From: Glen Waldrop
Sent: Tuesday, December 29, 2015 4:02 PM
To: af@afmug.com
Subject: Re: [AFMUG] WISP insurance
Forgot to mention, this was one hell of a storm.
Lightning from *several* miles away shook my home enough that the dishes
rattled, the TV moved, cabinet doors opened and closed, etc, for upwards of 45
seconds.
I’m honestly surprised we only lost one tower in that storm. I was preparing
myself for putting up at least a couple of replacement towers over my Christmas
break instead of goofing with the wife and kids. We got lucky and only lost
some electronics.
From: Glen Waldrop
Sent: Tuesday, December 29, 2015 4:57 PM
To: af@afmug.com
Subject: Re: [AFMUG] WISP insurance
It is grounded pretty well, couple of ground rods, tower is grounded and the
copper goes to the top, tallest point for quite a ways out there. The strike
also blew out the neighboring transformer (didn’t hit my equipment directly).
I have not been tying in my electrical ground with my tower ground. I do
believe I’m about to change that.
I do have a few other towers where the electrical ground is tied into the tower
ground which is also tied to a copper wire (6 or 8, depending on what I had at
the time) the entire length of the tower, bolted to the tower at the top and
bottom.
Those have also been struck.
One of my most recent ones ran up the ethernet cable, fried the equipment at
the top. POE on the ground survived, UPS survived and the surge suppressor
(10/100M fusible link essentially) survived. The only radio to survive the
strike was the only one I had forgotten to install a suppressor on. They were
all replaced of course. The only equipment I’ve seen survive an actual
lightning strike without a hiccup is the RB600. Everything else seems to die
within 6 months.
It appears the surge went through the ground (which we’ve gone over several
times) into the surge suppressor, into the ethernet and blew out the radios.
Any speculation on that would be awesome. The only thing that makes sense is
that maybe the static was close enough to hit the electrical ground and go up
the tower, but we’ve checked the ground rods and copper, bolts, etc.
From: Joshaven Mailing Lists
Sent: Tuesday, December 29, 2015 1:18 PM
To: af@afmug.com
Subject: Re: [AFMUG] WISP insurance
Kinda off topic... Insurance of another type (avoidance)
I often find locations where the grounds are hooked up to the tower ground
which includes one or more ground rods… but what often goes unrealized is that
the system is also grounded to another system through the utility company… and
the tower and the utility company may not be properly bonded. So the lightning
finds the big tower, and thinking it is a lightning rod… uses some of the path
to ground through rods at the base of the tower but then also uses the path
through the equipment to get to the power utility ground…. and pop goes the
radio and router and such… Just don’t be that guy that connects the big
lightening rod to the utility power ground through your router...
Your equipment should be surviving lightning strikes. Large towers can be
struck multiple times per month and equipment can be on them for years without
any damage at all. The fact that you lost equipment says that the strike was
either direct to your equipment or you have a grounding issue that made your
equipment a better path to ground.
At some sites commercial radio engineers will even bring in a beaded cable from
the tower and spread it across the floor to set all equipment on just to be
sure that the ground panes are entirely bonded. The reason that equipment
blows is that the difference in positive to negative current is out of range.
When you get a lightning strike and things are not well bonded then you can
have variances between grounds in the order of thousands of volts which will
make your equipment pop like a fire cracker… if your ground is at 10,000v
(relative to an average earth voltage) and your equipment is at 10,024v then
the potential between them is 24v. It is like a bird setting on a high voltage
line… somehow they don’t “feel” the high voltage… The trick to surviving a
lightning strike is to bond all grounds well so ground is constant and then to
have your power level referenced from that ground. This way if the earth
ground or the tower ground or anything else has a sudden change then your
equipment changes with it and remains relatively the same. After bonding your
grounds properly so that you don’t end up with thousands of volts difference
between two grounds like your power company ground and the tower that your
equipment is mounted to… then you can install good surge equipment that will
handle current overages in the event that you need it.
The thing to keep in mind when grounding your equipment is that you don’t want
your equipment to experience a situation like 0v for negative, 24v for positive
and 50,000v for ground. If your equipment ground plane floats with a strike
then it won’t even know that it experienced a surge. Just like a boat going
over shallower and deeper water — who knew unless they had a fish finder
running?
During a strike, you don’t want a 5,000v on the utility ground while you have a
25,000v on the tower… If the cable between the two (or patch of earth between
rods) won’t handle the surge or the impedance is too high then your equipment
will possibly have two grounds with two very different power levels so the
power will transfer from your shielded cable through your router chassis to the
utility power until a something pops. The bottom line make the tower, earth, &
utility power all the same and properly ground your equipment to that and
you’ll survive most strikes perfectly fine.
if you want some good reading google the terms: “copper.org lightning” they
have some great write-ups with pictures of the good, bad and ugly.
Sincerely,
Joshaven Potter
Google Hangouts: j...@g2wireless.co
Cell & SMS: 1-517-607-9370
supp...@joshaven.com
On Dec 27, 2015, at 10:31 PM, Craig House <cr...@totalhighspeed.net> wrote:
2 in a year? We had 7 last night.
Sent from my iPhone
On Dec 27, 2015, at 21:22, Glen Waldrop <gwl...@cngwireless.net> wrote:
We’ve had another lightning strike, at least the second one this year.
I’ve got this feeling that our insurance company is probably going to start
to get a little difficult in the near future.
Who do you guys recommend?
I’ve read about a few that cover everything, CPE, tower equipment, towers,
labor, etc... I imagine those probably cost roughly what we bring in a year,
but...
Thanks guys.
