Use a Ground or Lightning Rod?

[W. eWatson]

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.
--
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: <www.speckledwithstars.net/>

 

[Tom Biasi]

"W. eWatson" <notvalid2@sbcglobal.net> wrote in message
news:fpTXl.31440$Ws1.17163@nlpi064.nbdc.sbc.com...

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.
--
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: <www.speckledwithstars.net/

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

 

[W. eWatson]

Tom Biasi wrote:

"W. eWatson" <notvalid2@sbcglobal.net> wrote in message
news:fpTXl.31440$Ws1.17163@nlpi064.nbdc.sbc.com...
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.
--
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: <www.speckledwithstars.net/

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


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.


--
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: <www.speckledwithstars.net/>

 

[Nobody]

On Thu, 11 Jun 2009 08:31:00 -0700, W. eWatson wrote:

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?

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).

 

[ehsjr]

W. eWatson wrote:

Tom Biasi wrote:

"W. eWatson" <notvalid2@sbcglobal.net> wrote in message
news:fpTXl.31440$Ws1.17163@nlpi064.nbdc.sbc.com...

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.
--
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: <www.speckledwithstars.net/


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

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?

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

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.

 

[Rich Grise]

On Fri, 12 Jun 2009 04:18:32 +0000, ehsjr wrote:

W. eWatson wrote:

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?

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.

I'd also recommend using a heavy ground strap to bypass the rotator,

the way they do with water meters.

Cheers!
Rich

 

[Jasen Betts]

On 2009-06-10, Tom Biasi <tombiasi@optonline.net> wrote:

Keep in mind that lightning rods are not for getting hit, they are for
preventing hits by keeping the field bled off.

how does that work?

 

[Tom Biasi]

"Jasen Betts" <jasen@xnet.co.nz> wrote in message
news:h100ia$ts1$3@reversiblemaps.ath.cx...

On 2009-06-10, Tom Biasi <tombiasi@optonline.net> wrote:


Keep in mind that lightning rods are not for getting hit, they are for
preventing hits by keeping the field bled off.

how does that work?


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

 

[Bob Masta]

On Sat, 13 Jun 2009 07:29:41 -0400, "Tom Biasi"
<tombiasi@optonline.net> wrote:

"Jasen Betts" <jasen@xnet.co.nz> wrote in message
news:h100ia$ts1$3@reversiblemaps.ath.cx...
On 2009-06-10, Tom Biasi <tombiasi@optonline.net> wrote:


Keep in mind that lightning rods are not for getting hit, they are for
preventing hits by keeping the field bled off.

how does that work?


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

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

 

[Rich Grise]

On Sun, 14 Jun 2009 13:02:28 +0000, Bob Masta wrote:

On Sat, 13 Jun 2009 07:29:41 -0400, "Tom Biasi"
"Jasen Betts" <jasen@xnet.co.nz> wrote in message
On 2009-06-10, Tom Biasi <tombiasi@optonline.net> wrote:

Keep in mind that lightning rods are not for getting hit, they are for
preventing hits by keeping the field bled off.

how does that work?

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.

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.

Google "field emission".

Cheers!
Rich