Grounding roof antenna?

[Sudy Nim]

Installed new roof antenna, with new tripod mount and 10 foot pole (about 30ft.
roof to soil). Instructions say nothing about grounding. I have lived here (far
Chicago suburbs) 44 years and always connected tripod to soil pipe about 20 feet
away. Never had a problem with lighting strike, excluding several power line
incidents. Question to ground or not to ground? TIA

 

[Leonard Caillouet]

Installed new roof antenna, with new tripod mount and 10 foot pole (about
30ft.
roof to soil). Instructions say nothing about grounding. I have lived here
(far
Chicago suburbs) 44 years and always connected tripod to soil pipe about
20 feet
away. Never had a problem with lighting strike, excluding several power
line
incidents. Question to ground or not to ground? TIA

Actually, the instructions likely do detail the grounding requirements. If
not you will likely find them in the first pages of any television, or any
other receiving equipment. The mast for the antenna and the coax shield
must both be grounded to the ground electrode on your electrical service.

Leonard

 

[PeterD]

Installed new roof antenna, with new tripod mount and 10 foot pole (about 30ft.
roof to soil). Instructions say nothing about grounding. I have lived here (far
Chicago suburbs) 44 years and always connected tripod to soil pipe about 20 feet
away. Never had a problem with lighting strike, excluding several power line
incidents. Question to ground or not to ground? TIA

Code usually requires grounding.

 

[Sudy Nim]

Code usually requires grounding.

Thanks to all, appreciate your replies. I wired it to ground today.
Sudy Nim

 

[hr(bob) [email protected]]

Thanks to all, appreciate your replies. I wired it to ground today.
Sudy Nim

I hope you used a wire somewhat bigger than 26 gauge. Altho a direct
lightning strike of 20,000 amps or more will vaporize anything you
could reasonably use, the ground will help in the event of a nearby
strike. How far west of Chicago are you. I'm 28 miles out and we
get some humdingers here.

 

[GregS]

Yawn. The Central Florida area is the highest lightning area in the
country. Water everywhere, and almost as flat as your desert. I have
been inside buildings with no windows that were lit up like daylight
from the constant strikes. So close together that one hasn't completely
faded away before another one hits. The thunder so bad that the entire
building was shaking for over an hour, with no electricity, plus wind
and rain so hard you didn't dare step outside.

I have seen concrete buildings damaged, and lost a lot of electronics
as well. One TV studio got a direct hit on the building, past the
service entrance, and took out all kinds of equipment, including items
that weren't connected to anything.

Like the warming trend here in Pittsburgh, well this last summer was not as hot
as the previous two, but all the leaves are usually on the ground, or at
least thats the way it was 10 years ago. Its been unusually quiet
as thunder storms go. I sort of miss them. We have hill after hill, after hill, etc.
The worst and most trecherous sounding storm I have encountered, was up
right off Lake Erie, on flat land. I was scarred.

I was installing some guy poles off my new deck for a sun shade, out
of steel piping. I also attached some wiring to a ground post.
First time I ever put one of those long things in the ground. I still want to ground the steel
roof of my shed attached to the garage.


greg

 

[Bob Shuman]

My understanding is that the antenna ground wire is to provide an
"alternate" path for the very large, near instantaneous current (either
from ground to the sky/lightnining or from the lightning to the ground,
depending on the difference in the voltage potentials) that occurs when the
lightning "strikes" the metal mast.

Too small a conductor and it will be quickly vaporized leaving the current
to find its way to ground via some other (more destructive) path. Even if
the ground wire is of sufficient diameter to withstand the lightning strike,
it also needs to be as low of a resistance on that path as possible since
some portion of the current will nonetheless follow the path down the coax
based on the impedances seen in those two "parallel" paths to ground. The
goal here is simply to minimize any current down the coax so proper
attention needs to be given to the construction and length of the ground
conductor as well as the terminations on both ends too.

Bob

 

[GregS]

My understanding is that the antenna ground wire is to provide an
"alternate" path for the very large, near instantaneous current (either
from ground to the sky/lightnining or from the lightning to the ground,
depending on the difference in the voltage potentials) that occurs when the
lightning "strikes" the metal mast.

Too small a conductor and it will be quickly vaporized leaving the current
to find its way to ground via some other (more destructive) path. Even if
the ground wire is of sufficient diameter to withstand the lightning strike,
it also needs to be as low of a resistance on that path as possible since
some portion of the current will nonetheless follow the path down the coax
based on the impedances seen in those two "parallel" paths to ground. The
goal here is simply to minimize any current down the coax so proper
attention needs to be given to the construction and length of the ground
conductor as well as the terminations on both ends too.

Bob

I would agree with the path of least resistance, but as far as a single strike,
vaporizing the conductor is not going to stop the lightning like a fuse.. The vapor or plasma
probably has some conductivity anyway.

greg

 

[Sudy Nim]

Thanks to all, appreciate your replies. I wired it to ground today.
Sudy Nim

I hope you used a wire somewhat bigger than 26 gauge. Altho a direct
lightning strike of 20,000 amps or more will vaporize anything you
could reasonably use, the ground will help in the event of a nearby
strike. How far west of Chicago are you. I'm 28 miles out and we
get some humdingers here.

I used 1/8 inch galvanized wire rope. The grounding question appears to have

influenced some related interesting discussions. My property is in kind of a
valley, I'm about 20 feet lower than the surrounding area. The only lighting
problems I experienced at home are power line strikes, which resulted in blown
power line transformers, damaged TV's, appliances and burned out wall outlets.
Prior to retirement I made my living in the TV service industry so I have
personally seen the results of lighting. I often pondered if grounding the
antenna just attracts lighting? Just as I can not visualize how a radio or TV
dropped into a bathtub of water would electrocute you. But, I'll let someone
else experiment with that. Looks, as if we could be neighbors, you must know of
DuPage County?

 

[Sjouke Burry]

Someone mention using a thick wire for grounding..I was wondering if
that really was needed..by grounding the antenna isn't that just
changing the charge potential between the antenna and the ground.

Lightning is 100...1000 ths of amps.
A low resistance part to ground means less damage on
attached equipment, and less chance of starting a fire inside.
That also means, no curves and bends, to lessen inductivity.

 

[Bob Shuman]

Neighbor,

I too am living west of Chicago, IL in western Dupage County.

Bob

 

[hr(bob) [email protected]]

Neighbor,

I too am living west of Chicago, IL in western Dupage County.

  Bob





- Show quoted text -

Bob H is Bob Hofmann retired from Bell Labs EMC group in Naperville,
IL. I put myself thru college in the 1950's installing towers and
antennas and vacuum tube antenna boosters in Fort PIerce, Florida.
After a good summer storm, we could count on getting calls from people
whose tower amplifiers had been blown apart and whose 300 ohm twin
lead if intact had no conductivity because the copper had ben
vaporized into the poyethelene or what poastic was used for the
downleads. Nearest tv station was Miami, 125 miles away, so
amplifiers on towers was the only way to get signals. When West Palm
Beach went on the air, only 57 miles away, people began to get serious
about buying tv's since roofotp antennas becanme somewhat
practical.....

 

[Bob Shuman]

We were likely working at the Naperville, IL (Indian Hill) facility at the
same time and probably passed each other in the cafeteria or in the
hallways... BTW, I started there in 1979 and just a few months ago, moved
back to the same old building. So now it is ~30 years later and I work an
aisle away on the same floor and in the same building that I started in.
But it is an entirely different company now as you well know.

(Another) Bob

Neighbor,

I too am living west of Chicago, IL in western Dupage County.

Bob





- Show quoted text -

Bob H is Bob Hofmann retired from Bell Labs EMC group in Naperville,
IL. I put myself thru college in the 1950's installing towers and
antennas and vacuum tube antenna boosters in Fort PIerce, Florida.
After a good summer storm, we could count on getting calls from people
whose tower amplifiers had been blown apart and whose 300 ohm twin
lead if intact had no conductivity because the copper had ben
vaporized into the poyethelene or what poastic was used for the
downleads. Nearest tv station was Miami, 125 miles away, so
amplifiers on towers was the only way to get signals. When West Palm
Beach went on the air, only 57 miles away, people began to get serious
about buying tv's since roofotp antennas becanme somewhat
practical.....

 

[Sudy Nim]

Hi guys. I too climbed a few towers in my youth! I was with the big mother
(Motorola) from mid 50's until retirement. Started in consumer products (TV) in
Franklin Park. During my 35 years moved through various divisions, automotive,
military, communication etc. Last days at headquarters campus in Schaumburg.
Do not wish to get too personal here for all the world to see. Sudy Nim

 

[Bob Shuman]

Franklin Park = Quasar! With the works in the drawer for easy
serviceability?

Bob

 

[Sudy Nim]

Yep, that was the birth of the all transistorized color TV and last of the
breed. Division sold to a Japan Company and they continued under the Quasar name
for a short time in the Franklin Park plant before moving everything to Japan. I
was one of the fortunate few that did not lose my job and continued employment
in a different division. The main building is still there but empty for several
years and was supposed to be converted to rental apartments, condos or something
similar.

Sudy Nim