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Use a Ground or Lightning Rod?

Last week we had a terrific lightning storm, and it hit the TV mast, rotor, and antenna. That was witnessed by a neighbor. Although I had turned off a lot of computer equipment and unplugged quite a bit of it, I was on a trip but my wife was here, it knocked out the internet card on this computer and a hub in another building. Interestingly, the hub was not hooked to the electrical outlet. I had pulled it out. The rotor controller got zapped too. All else was fine. Maybe I just haven't used some other device that was damaged.

Terrain-wise we are really exposed, but do not have frequent lightning storms. There are no big trees near the house, and none higher than the house. Well, one. A ponderosa 50 feet from the house. We are at the highest point in the sparsely populated neighborhood. The closest home to us is

200'. The older neighbors around here said the storm last week was easily the strongest and most dynamic they've seen in there some 30 years here. No one thought to take pictures!

I'm quite sure the rotor, antenna, and mast are not grounded. The question becomes how to deal with a future strike. One is to ground the mast and rotor. Another is to just put up a lightning rod on the roof. Another is to just take down the antenna completely. We really don't use it any more. I've left it in place with some thought I might want to use it for local stations, which really are 60 miles away. Otherwise, we are on DirecTV.

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                                W. eWatson

              (121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
               Obz Site:  39° 15\' 7" N, 121° 2\' 32" W, 2700 feet

                     Web Page:
Reply to
W. eWatson
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Take down the antenna, It can't get hit if its not there. If you ground it you have a lightning rod. Keep in mind that lightning rods are not for getting hit, they are for preventing hits by keeping the field bled off. If you like you can put some lightning rods on your house. Surge protect all sensitive equipment at the power line and protect any incoming non-power line. A direct hit is beyond what mere mortals can tame.

Tom

Reply to
Tom Biasi

Sounds reasonable, but what would people in my position do if they had to depend on a TV antenna, and not DirecTV, etc.? Just use lightning rods?

I do find it odd that an ethernet card and a ethernet hub got hosed, especially when the hub was not electrically connected to anything other than an ethernet cable. Its wall wart was not plugged in. The ethernet cable between the house and the building with the hub is underground.

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                                W. eWatson

              (121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
               Obz Site:  39° 15\' 7" N, 121° 2\' 32" W, 2700 feet

                     Web Page:
Reply to
W. eWatson

You can get surge protectors for various types of cable, including TV antenna, ethernet, phone. Some of these are specifically designed for lightning (particularly the ones for TV antennae).

Reply to
Nobody

The National Electrical Code requires a lightning arrestor (they call it an antenna discharge unit) on ungrounded antenna lead in wires. It also requires that antenna masts and metal support structures be grounded. Properly installed, the antenna mast/support itself can act as a lightning rod. Failure to ground a metal antenna mast/support structure is asking for trouble.

Ed

Reply to
ehsjr

I'd also recommend using a heavy ground strap to bypass the rotator, the way they do with water meters.

Cheers! Rich

Reply to
Rich Grise

how does that work?

Reply to
Jasen Betts

Its a bit more involved than I could do justice here but the basic theory is that if the field around the rod can be prevented from building up and allowing what is called an 'early streamer' to form, then a strike can be averted. The rod system should be constructed to take a hit however. Tom

Reply to
Tom Biasi

I think a fair analogy is the "ionic wind" effect that you get with a sharp point attached to a Van de Graaff or other HV generator. The high potential difference around a point causes ions (and hence the charge difference) to be bled off.

Best regards,

Bob Masta DAQARTA v4.51 Data AcQuisition And Real-Time Analysis

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Scope, Spectrum, Spectrogram, Sound Level Meter FREE Signal Generator Science with your sound card!

Reply to
Bob Masta

Google "field emission". :-)

Cheers! Rich

Reply to
Rich Grise

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