What are you trying to lighten up?
.....ducking
On 12/29/2015 4:34 PM, [email protected] wrote:
About lightening... there is stuff there but didn’t find the
lightening stuff.
*From:* [email protected] <mailto:[email protected]>
*Sent:* Tuesday, December 29, 2015 3:33 PM
*To:* [email protected] <mailto:[email protected]>
*Subject:* Re: [AFMUG] WISP insurance
Did not find anything at copper.org
*From:* Joshaven Mailing Lists <mailto:[email protected]>
*Sent:* Tuesday, December 29, 2015 12:18 PM
*To:* [email protected] <mailto:[email protected]>
*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
<http://copper.org> lightning” they have some great write-ups with
pictures of the good, bad and ugly.
Sincerely,
Joshaven Potter
Google Hangouts: [email protected] <mailto:[email protected]>
Cell & SMS: 1-517-607-9370
[email protected] <mailto:[email protected]>
On Dec 27, 2015, at 10:31 PM, Craig House <[email protected]
<mailto:[email protected]>> wrote:
2 in a year? We had 7 last night.
Sent from my iPhone
On Dec 27, 2015, at 21:22, Glen Waldrop <[email protected]
<mailto:[email protected]>> 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.
