[CQ-Contest] spider balls

Grillo's ah3c at frii.com
Tue Jul 27 20:46:50 EDT 2004

Since we are on the subject of lightning, has anyone ever used "spider
balls" to dissipate energy thereby eliminating strikes on the structure?
These are a steel rod with over 200 fine spiked elements about 2 ft. long
each that create a cluster of very sharp spikes.

Can you visualize this?  I have three spider balls and am considering
installing one each about 40 feet up from the guy anchors on the steel guys
that would be connected to the anchor rods.  The balance of the guy lines up
to the top of the 120' tower are polyphaser cable, so are insulated.  I
would install three copper ground grids at each guy point and link them
together with underground copper cable.

The other thought is to mount them on top of the 120' tower and put one
ground grid under the tower.

I'm looking for alternatives before the concrete gets poured in 2 weeks....


----- Original Message ----- 
From: "Tom Rauch" <w8ji at contesting.com>
To: <keith at dutson.net>; "'TowerTalk'" <towertalk at contesting.com>
Sent: Tuesday, July 27, 2004 2:18 PM
Subject: Re: [TowerTalk] Lightning Strike - Epilogue

> > Analysis of the damage has revealed that the lines running
> from main house
> > to shack need to be grounded.  But I have decided on a
> better solution.  The
> > telephone line will be replaced with a new connection that
> will enter the
> > shack in a different location that is far from the power
> entrance.  The LAN
> > connection will be wireless.  The TV connection will be
> removed and a new
> > dish will be installed for the shack.
> Keith, I think you are making a mistake. You should bring
> all lines in at the same point, and bypass and ground them
> at that point.
> Moving a telephone line to the opposite end of the building
> is asking for trouble.
> Adding a separate small dish is OK, as long as it too enters
> near the power line and all share a common ground.
> > BTW, the bolt apparently hit the power lines in front of
> the house, after
> > the transformer.  The lines enter a weatherhead on another
> pole and run
> > through underground conduit to the main breaker panel.
> The 200 amp main
> > breaker did not get tripped.
> Maybe it there, but most likely not. The problems occured
> because current passed through your equipment on the way to
> different "grounds". From the extent of the damage when
> considering the nearly total lack of protection, it doesn't
> sound at all like a direct hit on your service entrance.
> Lightning might hit your tower and a large portion of the
> strike current will flow from the power line, since it is
> such a massive ground. It may hit a power line, and current
> flow from your tower ground through your equipment. It may
> have hit tree down the street, or a mile away.
>  The wireless LAN is good because it totally eliminates a
> path. The TV feed change at best won't help very much, and
> if you install a dish away from the power line entrance it
> can make the problem much worse than simply having a
> properly installed cable follow the power line to the shack.
> Moving the telco line away from the power line entrance will
> certainly make things much worse.
> The last thing we ever want to do is to isolate devices, and
> intentionally create multiple grounds and entrance points
> into a structure or equipment cluster. It is the worse
> possible thing to do.  This is why everyone universally
> recommends common point grounds and single point entrances.
> It's why telco and CATV lines enter near the utility
> entrance and share the same ground.
> You might consider looking at commercial installations and
> rethinking your plans. The next hit could be a disaster.
> 73 Tom
> _______________________________________________
> See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
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