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[Towertalk] re: bulkhead ground system

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Subject: [Towertalk] re: bulkhead ground system
From: (
Date: Thu, 25 Jul 2002 16:09:01 +0000
Man that's a bummer.  Sounds like your SPG is not 
connected to your service ground and also sounds like 
you don't have power line arrestors (not those cheap 
surge strips) on the power lines.  I'd suggest looking 
into these for future improvement.  Also, Polyphaser 
suggests that you not have any ground rods in a line 
that is towards the house, so that the energy is 
directed away from the house.  Finally they also suggest 
80 ft worth of ground radials (with rod spaced at a 
distance of 2 x the rod length) for each tower leg.  
Finally, I'd look at removing the ground wire from the 
same trench as the coax runs and place it in its own 
trench.  Maybe the energy ran along that wire and jumped 
over to the coax and then was too much for the arrestors 
at the SPG?  Gd luck; file an insurance claim.  Phil  
> At 09:51 AM 7/24/2002 -0300, Mike Gilmer, N2MG wrote:
> >N5OT wrote:
> > > > I still just disconnect everything when I am not using the station.
>   I agree...
> >This is probably the single most effective method for protecting your 
> >amateur equipment.  Even the SPG cannot be counted on entirely
> >protecting your stuff from nasties.  And one does not need to take a full 
> >hit to receive damage.  Close-by hits generate all kinds of
> >transients that take out stuff like phones, modems and trasceiver filter 
> >switching diodes all the time.
> My experience verifies this. I recently took a lighting induced surge. My 
> tower is 150' from my house. There are two 8' ground rods spaced 8' and 24' 
> from each leg connected to each leg via #4 bare copper. There is a #4 bare 
> copper wire buried in the coax conduit trench from the tower to the house, 
> with ground rods every 16', terminating at the power service entry and 
> bonded to the ground rod there. All my coax runs pass through PolyPhaser 
> lighting arrestors, which are mounted to a copper buss bar in the crawl 
> space under the house; the buss bar is tied to the ground system via #4 
> bare copper as well.
> The recent lightning stroke took out my TS-60, which was disconnected from 
> the antenna switch (Alpha-Delta) but connected to my 12VDC power 
> distribution system (Oak Bay fuse block). Both in-line fuses to the TS-60 
> were obliterated. There are burn marks on the coax jumper that goes from 
> the antenna switch to the radio; this jumper was lying near the switch, 
> disconnected, with the switch in the grounded position. There are also burn 
> marks from the metal cover of the fuse block to a piece of test gear 
> sitting near-by.
> My TS-850 will not power up either; fuse condition unknown at this time; 
> same deal; connected to 12VDC but no antennas.
> The stroke took out my computer, my ISDN router, computer monitor, video 
> card, network card, network hub, my wife's computer video card, the surge 
> suppressor on my wife's computer, who knows what else, as I am still 
> investigating. There were breakers opened in the breaker box in the house 
> and in my work shop; the stroke took out the stereo in the shop as well. 
> There are surge arrestors on all the computer gear, plus two of the power 
> company issued arrestors on the main panel.
> My 12VDC system is derived from an external battery pack which also 
> supplies my computer UPS. I think the surge came in on the house power 
> lines and found ground through the 12VDC system and radios. The UPS is the 
> only common component between the computers and the radios, due to the 
> 12VDC system. Perhaps I should break that up & have a separate 12VDC system 
> for the ham gear, but it still would be connected to AC mains at some 
> point. (Enter solar and wind system to power the shack).
> >I practice good hygiene and usually have the PL-259s (and all the AC, 
> >phone lines, LAN cables) disconnected at my station.
> I wasn't that thorough...should have been.
> >  However, the antenna/rotator/etc. wires still pass through something (a 
> > window or a wall) and enter the house.
> Same deal here.
> >  It is at that point one has allowed  "lightning" (or its effects) to 
> > enter and somehow at or near that point it should be dealt with - enter 
> > the SPG.
> I agree.
> >Mike N2MG
> >
> >
> >_______________________________________________
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> Thanks,
> Robin Midgett KB4IDC
> 615-477-8976 cellular
> 615-322-5836 office
> 615-773-4198 home
> _______________________________________________
> Self Supporting Towers, Wireless Weather Stations, see web site: 
> Call 888-333-9041 to place your order, mention you saw this ad and take an 
> additional 5 percent off
> any weather station price.
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