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When lightning strikes. FML.

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nmfire10
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When lightning strikes. FML.

Postby nmfire10 » Tue Jul 07, 2009 7:42 pm

Well didn't this just make my damn day. I wish I could bring up a historical radar image from OKX at about 2:30pm today. I was sitting at work watching this on the radar thinking "oh crap". About then is when the slew of text messages about things not working started flowing in from my firehouse. We're not sure where the hit was but it was either right outside the tower (on our property) or right outside the phone company CO (across the street). The flash and boom were basically synchronous so it was right there. From what people who were in the building at the time told me, it was quite the enlightening experience. It clearly came in through the phone circuits. You can literally trace the damage down the lines from device to device. Blasted voltage!

The fatality list so far is as follows:

- Every lightning arrestor on all the phone circuits got vaporized
- Phone PBX is toast. I have some spare cards but I'm not holding my breath after 250,000 amps
- DSL modem toast. It is blinking lights that aren't supposed to blink
- Router toast, not routing anything anymore
- LAN switch uplink port is toast... which was connected to router... which was connected to the modem... which was connected to the vaporized arrestor.
- Multiple RTPA and FDPA radio circuits are dead. Have no fear, AT&T is working on it.... :o

We're pretty sure something got fried in the CO which is resulting in the radio circuit failures. None of the radio equipment got wrecked (thanks to the arrestors and proper grounding doing their job) that I can tell but the circuits are dead. The only common link is that CO across the street. Considering the vaporized fusible bridge clips sitting on my desk right now, I'd say something over there got whacked too.

F-M-L.
"I'll eat you like a plate of bacon and eggs in the morning. "
- Some loser on rr.com

eBay at it's finest:
Me: "What exactly is a 900Mhz UHF CB?"
Them: "A very nice CB at 900Mhz speed!"

:-?

Will
Posts: 6823
Joined: Tue Sep 04, 2001 4:00 pm

Re: When lightning strikes. FML.

Postby Will » Wed Jul 08, 2009 2:06 pm

I am not a fan of the lightning protection for phone and radio lines. We see the same thing here is So. California.

Back in the days.. the telco had coils on the cable side of the circuits that would absorb most of the lightning shock. No more coils here anymore.

Also most telco lightning zappers have way to high of an ark over voltage.

Satelite
Posts: 652
Joined: Sat Aug 12, 2006 10:43 am

Re: When lightning strikes. FML.

Postby Satelite » Wed Jul 08, 2009 2:23 pm

Hello:
Same experience here with lightning strikes from telco side.
The arrestors today do not effectively absorb the local strikes.
I have however had some success with distant strikes from the telco lines protected with the Gas Fet arrestor style protection for the telco side.
As for electrical co. side i use the 2 phase line arrestor one each on the 120 volt lines and it has done me well for protection on the transient strikes that cause high surges.
As for protection from direct lightning strikes on the tower antenae - Well my experience has been BEND OVER AND KISS YOUR SYSTEM GOOD BYE.
Usauly too much damage that after repair the reciever sensativity suffers and you settle for less than desirable performance.
So i let the system die a complete death and the inland marine insurance policy replaces it as new.
Satelite

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nmfire10
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Re: When lightning strikes. FML.

Postby nmfire10 » Wed Jul 08, 2009 6:56 pm

I've been outside looking for ground zero but I can't find it. It only hit the phone circuits and it only effected OUR circuits, none of the neighbors. It did not effect line power or cable TV. So I think the strike was on our property, hit the dirt or something, and went into the underground conduit with the 50 pair cable that goes from the firehouse to the radio tower hut. Its the only logical explanation.

The arrestors saved the radio equipment without a doubt. There was a desktop tone remote hooked up before the arrestor and it was literally melted. The phone company CO had fried MFT's which were also obviously not on the protected side of our arrestors. All our radio equipment on the protected side of the lightning arrestors was all unharmed.
"I'll eat you like a plate of bacon and eggs in the morning. "
- Some loser on rr.com

eBay at it's finest:
Me: "What exactly is a 900Mhz UHF CB?"
Them: "A very nice CB at 900Mhz speed!"

:-?

Satelite
Posts: 652
Joined: Sat Aug 12, 2006 10:43 am

Re: When lightning strikes. FML.

Postby Satelite » Wed Jul 08, 2009 8:50 pm

Hello :
Id have to agree with you with your description of the strike.
It sounds like you had a transient strike and not a direct strike to the antenae.
In this case i have had good luck with protecting the system.
Its those direct lightning strikes i have not been able to protect the equipment from.
Satelite

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nmfire10
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Re: When lightning strikes. FML.

Postby nmfire10 » Thu Jul 09, 2009 6:13 am

I've been doing a lot of explaining to people the concept to lightning protection. Like you said, nothing is going to save the equipment from a direct strike. 120 million volts at 30,000 amps is going to wreck everything in its path. It traveled 10 miles through the air without a problem, there is very little you can put in front of it to stop it. The obsessive compulsive grounding and protection devices will limit the damage of the connected equipment and prevent the rest of the building from burning down. For an indirect hit, the protection device can save the equipment too. In this case, that seems to be what happened.
"I'll eat you like a plate of bacon and eggs in the morning. "
- Some loser on rr.com

eBay at it's finest:
Me: "What exactly is a 900Mhz UHF CB?"
Them: "A very nice CB at 900Mhz speed!"

:-?

GMC
Posts: 150
Joined: Sun Sep 09, 2001 4:00 pm

Re: When lightning strikes. FML.

Postby GMC » Fri Jul 10, 2009 6:39 am

Hello,

Has anyone else used any of the porta system stuff??? I have had very good results with there line of plug in modules.

http://www.portasystems.com/Protection/ ... sindex.htm

Jim202
Posts: 3567
Joined: Sun Sep 09, 2001 4:00 pm

Re: When lightning strikes. FML.

Postby Jim202 » Fri Jul 10, 2009 9:06 am

Not that I am trying to wind anyone up on the board here, but a site can take a direct hit and stay
running. I use to work for a cellular company in the New Orleans area. The towers down there
would take direct hits all the time. Was in my vehicle one time and saw the tower take the strike.
It was raining at the time so the tower was wet. After the strike, the tower was steaming for
a good portion of it's length from the heat of the high current going through it.

After the storm calmed down, I went inside the equipment shelter and everything was operating just
like it should. Went inside another building and the ham equipment repeaters were just working fine.
There were a couple of business radios that the site owner had been trying to to get the radio owners
to ground the radio cabinet, coax cable and put surge protectors on the power feed. They wouldn't
spend the effort or money to do it. Well guess what, they got hit.

Haven't you ever watched a TV station during a storm and seen them go off the air for about 30
seconds to a minute and come back just like nothing happened. You can protect a site with a good
ground and surge protection system. Note that I used the term system. No one ground or single
surge protector will do the job, but when all is done together, it works. Otherwise all the wireless
companies couldn't afford to keep replacing their expensive equipment.

If your site and radios are being damaged, I would suggest you take a long hard look at the grounding
system for the equipment shelter and tower. Then look at the power surge protection. Don't forget
to include the telephone line surge protection in there. It all can be made to work and have your
equipment come out of it still playing.

Still not a believer, then I guess you will never be convinced that protection does work.

Jim

Satelite
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Joined: Sat Aug 12, 2006 10:43 am

Re: When lightning strikes. FML.

Postby Satelite » Fri Jul 10, 2009 3:01 pm

Hello :
True i myself have also taken direct strikes to the tower itself and survived many timers.
But i seem to have no luck from the direct strike to the antenae straight down the coaxial feed line to the radio equipment.
Yes they make coaxial arresstors but they still didnt keep me on line.
Still had damage to repair.
Satelite

Jatla
Posts: 23
Joined: Thu Jan 13, 2005 4:38 pm

Re: When lightning strikes. FML.

Postby Jatla » Sat Jul 11, 2009 7:01 am

Don't forget, lightning protection is all about voltage differences. Not the fact of a local 100 Million Volt discharge, but the fact that the earth around the tower briefly comes up to a similar potential as the cloud from which the lightning bolt originates. As long as all of the elements of the radio system are very close in potential when the strike hits, there will be no serious damage. The tower down the road may be 50 Million Volts lower in absolute potential, but locally all of the parts of the struck system can be all within a few millivolts for a few microseconds thus no serious current flow. It is the current flow from voltage differences that does the damage. The obsessive-compulsives amongst us that constantly check for degradations in the bonding and other connections, as well as ground resistance will be the ones on the air after a strike.
Standing by...

Glen W Christen
Posts: 203
Joined: Sun Sep 09, 2001 4:00 pm

Re: When lightning strikes. FML.

Postby Glen W Christen » Mon Jul 20, 2009 10:01 am

Years ago one of our customers took a lightning hit on their tower. The result was three antennas blown clear off the tower and the power company's transformer blown off the pole. The strike hit the building, vaporized the meter panel and blew a 4-foot hole through the wall but didn't start a fire. Needless to say, the equipment was badly damaged, and this was before synthesized units ready for direct substitution.


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