[TowerTalk] Grounding of Amateur Radio installations

[Pete Smith]

Actually, I took a direct hit on my 40M yagi some 3 years ago, about 200 feet from the house and 100 feet in the air.  Thanks to disconnection, I lost nothing on the radio side in the shack.  Unfortunately, my wired Ethernet network connections made a good antenna, and  the induced EMP killed both computers.  Aside from them, we lost only the stuff on the tower, and a telephone answering machine.  I'm not sure that additional measures would do much to improve on this.

73, Pete N4ZR

At 09:55 AM 12/8/2006, Phil Camera wrote:
>Even though a second floor shack is not optimum, installing a well designed grounding system is not out of the realm of possibilities.  Polyphaser has a good technical article discussing exactly this problem.
> 
>In summary a well designed grounding system consists of the following elements:
> 
>1.  Tower or mast ground
>2.  SPG
>3. Lightning arrestors
>4. Shack ground
>5.  Service entrance ground
> 
>All five must be tied together, outside, for it all to work.  Leave out any part, and Mother Nature has an entry route.  Yes, being upstairs from your SPG is a problem but what you'd need to do is install the lowest resistance/impedance ground from your shack to the rod.  The best would be copper strip a number of inches wide.  With everything listed connected together, when your system gets that energy surge from a strike or nearby strike (up to a mile away can induce enough current to fry electronics) then everything rises in voltage together and there is no potential difference between grounds which is what zaps your electronics.
> 
>Simple disconnetion outside can work, as far as eliminating the lightning arrestor part of the above list but you'd then still need to take care of all the other listed items.  A surge via your power lines can also zap your electronics even if the coax is disconnected.  The best would be to totally disconnect your rig and put it in the closet but I'd doubt you'd do it every time and it only takes one time to get bummed out.   Worst case you might have lightning getting into the house and that can be bad also.
> 
>Phil  KB9CRY
> 
>-------------- Original message -------------- 
>From: Pete Smith <n4zr at contesting.com> 
>
>> At 09:18 AM 12/8/2006, Phil Camera wrote: 
>> >"Something to bear in mind is that, in general, most jurisdictions don't bother 
>> enforcing the NEC for amateur radio antennas" 
>> > 
>> > 
>> >Which actually is too bad because these guidelines are exactly the measures one 
>> should do for a properly installed safety & lightning prevention grounding 
>> system. And every single measure must be in place or else you're leaving an 
>> entry route for Mother Nature to bite you. 
>> > 
>> >Phil KB9CRY 
>> 
>> Which is fine if your shack is in an optimal location so that you can do 
>> everything by the book, but what if it's on the second floor of an old house? I 
>> attempt a single-point ground in th e shack, but it is a long way from earth 
>> ground. I am not so naive as to believe I'm going to be able to survive a hit 
>> if the cables from my tower are connected. Is simple disconnection at the shack 
>> entrance up to code? I don't know, but it's all I have. 
>> 
>> 73, Pete N4ZR 
>>