[TowerTalk] Lightning Protection

Sat Jul 6 10:13:56 EDT 2013

I've watched this discussion on the subject of grounding go round-and 
thought I might as well throw my two cents in the ring. One of the best 
written pieces on approaching
grounding I have come across was written by W8JI. I have included a link 
to that article for the your reading and subsequent discussion pleasure. 
I can only tell you that living in
the lightning capital of the world and having implemented W8JI's 
recommendations, I have not lost any equipment yet. Read the article and 
then ask yourself how many of the
recommendations have you implemented - are you close to the "Best by 
Far" or not even close? The link to the article (and other interesting 
articles on grounding, lightning, etc.)
is: http://www.w8ji.com/house_ground_layouts.htm     73's, Dave, K4CTV

On 7/6/2013 5:13 AM, Nick N3NR wrote:
> A good reference on the subject relative to commercial systems is the 
> Motorola R56 manual. It's slightly dated, but still a good reference. 
> I have seen this manual called out frequently as a reference, or 
> sometimes even a requirement, for commercial systems.
>
> You can find a copy here: 
> http://www.radioandtrunking.com/downloads/motorola/R56_2005_manual.pdf
>
> Lots of examples and ideas.
>
> 73 de Nick N3NR
> ----- Original Message ----- From: "K8RI" <K8RI-on-TowerTalk at tm.net>
> To: <towertalk at contesting.com>
> Sent: Friday, July 05, 2013 11:46 PM
> Subject: Re: [TowerTalk] Lightning Protection
>
>
>> On 7/5/2013 3:44 PM, Pete Smith N4ZR wrote:
>>> Every time Towertalk starts off on one of these threads I feel 
>>> compelled
>>> to add one skeptic's viewpoint, and this time I'm actually going to 
>>> do it.
>>
>> I'm not a EE but I managed to get over in while earning a degree in CS.
>>
>> I have a 100' 45G that had a 30' mast with a TH5 at 100', a 7L C3i 
>> 6-meter Yagi at 115' and a cross boom at 130 feet with a pair of 11L 
>> 440s ans a pair of 12L 144 antennas.
>> http://www.rogerhalstead.com/ham_files/Tower29.htm
>> When first installed this system took  at least 3 direct hits a year 
>> for a total of 17 visually verified hits the first 6 years it was up. 
>> The only loss was one Polyphaser at the entrance.
>> There is over 600 feet of bare #2 CadWelded to 32 or 33 8' ground 
>> rods. There are two parallel runs from the tower to the grounding 
>> panel and ground rods at the entrance.
>> http://www.rogerhalstead.com/ham_files/cablebox.htm  The photo at the 
>> entrance is out of date as that panel/box has been replaced with a 
>> larger one.
>>
>> During that time the rigs remained connected to the antennas, power, 
>> computers and network.  They stayed connected because the connections 
>> were very difficult to access.  I was more concerned about the 
>> connections to the computers and network as they are on a different 
>> circuit along with the cable connection.
>>
>> BTW the stations in the house and shop are on serrate electrical 
>> feeds although from the same transformer,
>>
>>> Unless you are an electrical engineer with deep understanding of
>>> lightning protection, I think that attempts to replicate a commercial
>>> 24/7 always-connected solution are far more likely to fail than to
>>> succeed.
>>
>> Lightening protection is pretty well standardized and there is plenty 
>> of information available.  There is no 100% guaranteed, fail safe 
>> protection even for the 24 X 7 stations, but they are well protected 
>> from most strikes.  It's just that there is no guaranteed protection 
>> from the so called, "super strikes" that can be many times more 
>> powerful than your run of the mill, every day strikes.
>>
>> So, yes, the best protection is to disconnect everything from 
>> everything else, not just the antennas and power.  Remember a strike 
>> a mile away can induce as much as a 1000 volts per meter into a piece 
>> of wire,
>>
>> Another danger is precipitation static,  What heavy snow in high wind 
>> can induce into an ungrounded quarter wave, 40 meter vertical is 
>> something to behold and I've never seen an ignition coil produce that 
>> kind of voltage.
>>
>> Twas about 35 years ago.  We were in the process of building a house 
>> on the NW corner of the family farm.  I had a 40 meter, 1/4 wave 
>> vertical about a 100 feet out.  The rig, a Kenwood TS820, was 
>> disconnected.  A very strong wind was blowing with heavy snow.  I 
>> kept hearing a loud snap or pop!  I looked behind the rig and was 
>> surprised to see a FAT blue ARC across the PL259.  The thing is, it 
>> wasn't just cross the end but rather arched out a good inch away from 
>> the end of the connector, forming a loop that appeared to be close to 
>> a couple of inches long and it was loud!. Rain with strong wind can 
>> also produce similar results.
>>
>> I've seen similar results from nearby lightening strikes from the 
>> feedline to the 75 meter dipole.
>>
>>
>> <snip>
>>
>> 73
>>
>> Roger (K8RI)
>>
>> _______________________________________________
>>
>>
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