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Posted by Tony Hwang on January 13, 2008, 5:55 pm
Red wrote:
>
>>
>>
>>> I didn't say a strike, I said a surge.
>>> I've lost 3 tv's at a different location fromlightningsurges
>>>(nearby but not direct strike) coming into the tuner section via
>>>CATV.
>>
>> First a lightning strike is a surge.
>>
>> Second, sacrificial protection does not exist - is a myth. A surge
>>is electricity. That means electricity flows through everything in
>>that path from cloud to earth. Only after does something or multiple
>>things fail. You have assumed surges do damage like waves crashing on
>>a beach. Electricity does not work that way.
>>
>> Third, protection is defined in another post on 11 January 2008 in
>>the newsgroup newsguy.general entitled "Lightning Strikes" at:
>> http://tinyurl.com/22race
>>Everything in that post defines what provides TV protection.
>>
>> Fourth, you have assumed lightning surge entered on cable. Then what
>>is the outgoing path to earth? Any properly installed cable first
>>connects to earth ground before rising up to enter the building.
>>Connected to earth means a surge will not seek earth ground,
>>destructively, via the TV. What is the incoming surge path? What
>>good is a 'sacrificial' amp when cable should already dump the
>>incoming surge to earth before entering the building?
>>
>> Fifth, surges typically enter from wires located highest on poles -
>>AC electric. Incoming on AC electric, into TV, and out to earth
>>ground via tuner and cable. Protection means the incoming wire should
>>be earthed before entering the building. That is what one properly
>>earthed 'whole house' protector does. Earthed to the same electrode
>>that cable TV wire connects.
>
>
> I'm not going to get into this argument again - it was fought long &
> hard many times before. All I'm saying is that theory is one thing
> and experience is another. As to cable input, the shield is grounded
> but the center conductor is not. Any induced voltage on the center
> conductor goes into the tv's tuner section before it finds a path to
> ground. And I've had 3 tv's to prove it despite what theory says.
> Also, it does not take a strike to create a surge. Many, many times
> I've had static electricity jumping 1" to 2" arcs between appliances
> in my kitchen when there was a storm in the area but no strikes. I've
> had items vibrate on my glass coffee table many seconds before a
> strike a half mile away. And yes, my house is properly grounded.
> And yes, I have had a lot of experience installing commercial
> lightning protection sysyems. Enough experience to say that lightning
> will do what it damn well pleases despite what precautions we take.
> So the more we do, even it is not within norm, increases our chances
> of minimal damage. And that is what I said I did.
>
> Red
Hi,
Yes, speaking of experience, when I was an EIC at LARGE data center in
the basement of a building, we suffered a direct hit. No visible damage
to any equipment per se, but alas, our data stored in the mass storage
devices were all garbled(trashed) needing 3 days non-stop restore
operation from a back up we kept off site. I think when hit direct,
there is no real 100% protection.
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