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Antenna in Attic Question


CapZark
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Grounding is not necessary to protect from lightning simply because it will not protect anything if you get a direct lightning strike. The only thing that would protect against something so catestrophic is a home lightning rod system. You are better off not grounding so it does not introduce a ground loop into your system.

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Grounding is not necessary to protect from lightning simply because it will not protect anything if you get a direct lightning strike. The only thing that would protect against something so catestrophic is a home lightning rod system. You are better off not grounding so it does not introduce a ground loop into your system.

The correct way to do it, if you want lightning protection, is to bring the coax outside the house (possibly through the gable vent, or a small hole) and take it to ground level where it can be attached to a properly designed and installed lightning arrestor (such as available from Polyphaser or Industrial Communications Engineers). The coax coming out of the arrestor can then be routed back into the house as desired. As stated above, attic mounting does not offer protection from a direct hit, so if you are in a high lightning area you are taking a big chance. Additionally, if the grounding of the antenna is properly executed, you will have no ground loop problems.

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Grounding via a coax shield for lightning protection is absolutely useless. If you wanted to truly protect your antenna and system you should put up a home lightning protection system that completely eliminates the antenna from getting hit. There is really no other protection. Grounding an RG-6 coax, then running it into your stereo system, and expecting its shield to channel lightning is good way to set up your system for it all to be destroyed. Don't connect any ground wire.

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Lightning just burns out the braid on the co-ax, whether or not it's grounded.

_Sometimes_ what it was hooked to can be repaired.

djk is quite correct. A direct hit to the antenna would vaporize the antenna and the connected coax. But, in the process, many kilovolts would pass through the coax into any connected equipment, and possibly into the house wiring. The devices by Polyphaser and ICE are designed to prevent such connected equipment from that event when installed correctly. That is why the coax needs to be brought outside the house to ground level for connection to the protective device. A number of ham operators I know have taken direct hits to their tower mounted antennas (in some cases at 75-100 feet above ground), but the connected equipment remained intact!

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Perhaps an antenna in the attic can collect a nearby static discharge but if it takes a direct strike you got bigger problems.

That's quite correct. Even a nearby thunderstorm (or snowstorm) can induce charges of hundreds of volts in antennas regardless of where they are mounted. To think of having any kind of antenna installation which is not protected is a mistake. A properly designed discharge unit constantly drains all induced voltages to ground (as opposed to those which don't discharge until a predetermined voltage is present) which makes the antenna less "attractive" to the step leader which preceeds the lightning strike itself. These units are not only grounded, but also bonded to the ground system of the building's electrical service, telephone service, and if copper plumbing is present to that as well. There are many sites which discuss the correct way to install lightning protection for antennas including Polyphaser's and ICE's.

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This forum is great - I was just wondering if I might attract more lightning if I put this thing in the attic say verses the basement near a window. If may chance of burning down the house is the same either way it's going in the attic. I don't care if my stereo blows up as long as I don't. I just don't want to stick something up there that might make Mr. Lightning like me more than my neighbor. Very interesting posts. I've enjoy ever one's knowledge and feedback. Thanks.

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