Forums

Antenna Lightning Protection

Started by W. eWatson September 19, 2013
I have a mast, rotor and yagi TV antenna on my roof. The antenna is 
probably 15' feet above the roof. It has 12 or so large elements, and a 
similar amount of smaller elements. There are three guy wires. It was 
struck by lightning about eight years ago, and took out the rotor 
control in the house. There was no apparent damage to the antenna it is 
not in use, disconnected from the TV, but the antenna wire goes into the 
house. It is easily the tallest structure around the house, that is, no 
trees accept a tall pine about 80' away, which is close to the height of 
the antenna.

About the end of August and to mid-Sept. we have occasional electrical 
storms. We had a strong storm near our house 2 weeks ago. My question is 
should I have the antenna taken down or somehow grounded.  If the latter 
what's a conventional way to do it?  Copper wire from the base of the 
mast down the side of the house to a ground pipe? The antenna is about 
20' from the end of the roof near it. I'm not sure of the material used 
for the mast. It may be aluminum.
On Thu, 19 Sep 2013 14:49:15 -0700, "W. eWatson"
<wolftracks@invalid.com> wrote:

>I have a mast, rotor and yagi TV antenna on my roof. The antenna is >probably 15' feet above the roof. It has 12 or so large elements, and a >similar amount of smaller elements. There are three guy wires. It was >struck by lightning about eight years ago, and took out the rotor >control in the house. There was no apparent damage to the antenna it is >not in use, disconnected from the TV, but the antenna wire goes into the >house. It is easily the tallest structure around the house, that is, no >trees accept a tall pine about 80' away, which is close to the height of >the antenna. > >About the end of August and to mid-Sept. we have occasional electrical >storms. We had a strong storm near our house 2 weeks ago. My question is >should I have the antenna taken down or somehow grounded. If the latter >what's a conventional way to do it? Copper wire from the base of the >mast down the side of the house to a ground pipe? The antenna is about >20' from the end of the roof near it. I'm not sure of the material used >for the mast. It may be aluminum.
Take it down. It's an "attractive" nuisance ;-) ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
On Thu, 19 Sep 2013 14:56:38 -0700, Jim Thompson  
<To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote:

> On Thu, 19 Sep 2013 14:49:15 -0700, "W. eWatson" > <wolftracks@invalid.com> wrote: > >> I have a mast, rotor and yagi TV antenna on my roof. The antenna is >> probably 15' feet above the roof. It has 12 or so large elements, and a >> similar amount of smaller elements. There are three guy wires. It was >> struck by lightning about eight years ago, and took out the rotor >> control in the house. There was no apparent damage to the antenna it is >> not in use, disconnected from the TV, but the antenna wire goes into the >> house. It is easily the tallest structure around the house, that is, no >> trees accept a tall pine about 80' away, which is close to the height of >> the antenna. >> >> About the end of August and to mid-Sept. we have occasional electrical >> storms. We had a strong storm near our house 2 weeks ago. My question is >> should I have the antenna taken down or somehow grounded. If the latter >> what's a conventional way to do it? Copper wire from the base of the >> mast down the side of the house to a ground pipe? The antenna is about >> 20' from the end of the roof near it. I'm not sure of the material used >> for the mast. It may be aluminum. > > Take it down. It's an "attractive" nuisance ;-) > > ...Jim Thompson
I second that. Take it down. To understand why, remember what you just described to 'protect' it, that is, make it grounded better?! Big ouch. Seriously, it's bad enough *IF* you must have that in the air, but to not need it and leave it is, ...like an invitation. And believe me. you were lucky to only have damaged the rotor last hit.
"W. eWatson" <wolftracks@invalid.com> wrote in message 
news:l1frgt$n2n$1@dont-email.me...
>I have a mast, rotor and yagi TV antenna on my roof. The antenna is >probably 15' feet above the roof. It has 12 or so large elements, and a >similar amount of smaller elements. There are three guy wires. It was >struck by lightning about eight years ago, and took out the rotor control >in the house. There was no apparent damage to the antenna it is not in use, >disconnected from the TV, but the antenna wire goes into the house. It is >easily the tallest structure around the house, that is, no trees accept a >tall pine about 80' away, which is close to the height of the antenna. > > About the end of August and to mid-Sept. we have occasional electrical > storms. We had a strong storm near our house 2 weeks ago. My question is > should I have the antenna taken down or somehow grounded. If the latter > what's a conventional way to do it? Copper wire from the base of the mast > down the side of the house to a ground pipe? The antenna is about 20' from > the end of the roof near it. I'm not sure of the material used for the > mast. It may be aluminum.
IF you leave it up (which is probably the worse option) then I'd suggest you run copper wire from the TOP of the mast, all the way down. Ideally this 'down conductor' (as some call it) has no sharp bends in it and preferably no bends greater than 90 degrees. I'm not 100% sure what you mean when you say ground pipe, but I would connect the down conductor to a ground rod (10' long rod, steel or copper clad steel depending whether your soil eats up unprotected steel, 3/4" diameter, pounded straight down into soil until it's top is about a foot below ground). Ideally that rod is 2m (or 4m or more) away from your house's ground (be that a rod, underground metallic water pipe, or whatever). You could then connect the ground rod to your ground system with a #6 AWG bare copper wire. j
On 9/19/2013 7:13 PM, operator jay wrote:
> "W. eWatson" <wolftracks@invalid.com> wrote in message > news:l1frgt$n2n$1@dont-email.me... >> I have a mast, rotor and yagi TV antenna on my roof. The antenna is >> probably 15' feet above the roof. It has 12 or so large elements, and a >> similar amount of smaller elements. There are three guy wires. It was >> struck by lightning about eight years ago, and took out the rotor control >> in the house. There was no apparent damage to the antenna it is not in use, >> disconnected from the TV, but the antenna wire goes into the house. It is >> easily the tallest structure around the house, that is, no trees accept a >> tall pine about 80' away, which is close to the height of the antenna. >> >> About the end of August and to mid-Sept. we have occasional electrical >> storms. We had a strong storm near our house 2 weeks ago. My question is >> should I have the antenna taken down or somehow grounded. If the latter >> what's a conventional way to do it? Copper wire from the base of the mast >> down the side of the house to a ground pipe? The antenna is about 20' from >> the end of the roof near it. I'm not sure of the material used for the >> mast. It may be aluminum. > > IF you leave it up (which is probably the worse option) then I'd suggest you > run copper wire from the TOP of the mast, all the way down. Ideally this > 'down conductor' (as some call it) has no sharp bends in it and preferably > no bends greater than 90 degrees. > > I'm not 100% sure what you mean when you say ground pipe, but I would > connect the down conductor to a ground rod (10' long rod, steel or copper > clad steel depending whether your soil eats up unprotected steel, 3/4" > diameter, pounded straight down into soil until it's top is about a foot > below ground). Ideally that rod is 2m (or 4m or more) away from your > house's ground (be that a rod, underground metallic water pipe, or > whatever). You could then connect the ground rod to your ground system with > a #6 AWG bare copper wire. > > j > >
By pipe, I really meant about a six foot copper pipe, 1/2" or so. Yes, taking it down the antenna seems a sensible way to go. I'll get the fellow who put it together many years ago to remove it. To Robert, a bad choice of words to Subject. By the way the roof peak is about 60' long, and a roof, lower, is about 35' long. So what's some simple way to protect us from being hit? Someone years ago suggested four lightning rods strung out along the peak was a way to go, with them all grounded. One end of the line along the peak would go down the side of the house to the ground. So is there
"W. eWatson" <wolftracks@invalid.com> wrote in message 
news:l1gbi0$4cq$1@dont-email.me...
> On 9/19/2013 7:13 PM, operator jay wrote: >> "W. eWatson" <wolftracks@invalid.com> wrote in message >> news:l1frgt$n2n$1@dont-email.me... >>> I have a mast, rotor and yagi TV antenna on my roof. The antenna is >>> probably 15' feet above the roof. It has 12 or so large elements, and a >>> similar amount of smaller elements. There are three guy wires. It was >>> struck by lightning about eight years ago, and took out the rotor >>> control >>> in the house. There was no apparent damage to the antenna it is not in >>> use, >>> disconnected from the TV, but the antenna wire goes into the house. It >>> is >>> easily the tallest structure around the house, that is, no trees accept >>> a >>> tall pine about 80' away, which is close to the height of the antenna. >>> >>> About the end of August and to mid-Sept. we have occasional electrical >>> storms. We had a strong storm near our house 2 weeks ago. My question is >>> should I have the antenna taken down or somehow grounded. If the latter >>> what's a conventional way to do it? Copper wire from the base of the >>> mast >>> down the side of the house to a ground pipe? The antenna is about 20' >>> from >>> the end of the roof near it. I'm not sure of the material used for the >>> mast. It may be aluminum. >> >> IF you leave it up (which is probably the worse option) then I'd suggest >> you >> run copper wire from the TOP of the mast, all the way down. Ideally this >> 'down conductor' (as some call it) has no sharp bends in it and >> preferably >> no bends greater than 90 degrees. >> >> I'm not 100% sure what you mean when you say ground pipe, but I would >> connect the down conductor to a ground rod (10' long rod, steel or copper >> clad steel depending whether your soil eats up unprotected steel, 3/4" >> diameter, pounded straight down into soil until it's top is about a foot >> below ground). Ideally that rod is 2m (or 4m or more) away from your >> house's ground (be that a rod, underground metallic water pipe, or >> whatever). You could then connect the ground rod to your ground system >> with >> a #6 AWG bare copper wire. >> >> j >> >> > By pipe, I really meant about a six foot copper pipe, 1/2" or so. > > Yes, taking it down the antenna seems a sensible way to go. I'll get the > fellow who put it together many years ago to remove it. > > To Robert, a bad choice of words to Subject. > > By the way the roof peak is about 60' long, and a roof, lower, is about > 35' long. > > So what's some simple way to protect us from being hit? Someone years ago > suggested four lightning rods strung out along the peak was a way to go, > with them all grounded. One end of the line along the peak would go down > the side of the house to the ground. > > So is there
Your reply looks to have gotten cut off. If I understand correctly you have a peaked roof on which the peak is 60'long, and if you rolled down the slope away from the peak, you would go over an edge, and drop onto another sloped roof. This lower sloped roof is about 35' long, and sloped in the same direction as the higher roof. Also, I have been assuming a shingle roof. Yes, four lightning rods ("air terminals", probably about 20" tall each) along the peak, with a conductor connecting them all, takes care of the peak. Then, from the same end of the peak, two conductors could run down the slopes from the peak to the edges of the roof (the conductors running down from the peak would still be on top of the roof, but near the edge of the roof). One conductor would go over the edge of the roof and down to a ground electrode. The other conductor would go over the edge of the roof, drop to the lower roof, run down the edge of that lower roof to a corner, then go over the corner and down to a ground electrode. Those electrodes should prbably be interconnected to each other, and to the house's ground. The rods should be 2 or 3 feet out from the building. I don't recall for sure, but I think you could probably do without the air terminals - the conductor running along the peak acts as an "intercepting conductor" and takes the lightning hit. Take a look at this site, http://www.tlpinc.com/ Browse EVERYTHING under "DOC LIBRARY" and I think you'll have a decent feel for what's going on. The product catalogs under the doc library not only have the major components, but also all the accessories and fittings. I have no affiliation with that or any website or manufacturer. I know those products and I think that site will be helpful to you. Good luck. j
On Thu, 19 Sep 2013 19:22:55 -0700, "W. eWatson"
<wolftracks@invalid.com> wrote:

>On 9/19/2013 7:13 PM, operator jay wrote: >> "W. eWatson" <wolftracks@invalid.com> wrote in message >> news:l1frgt$n2n$1@dont-email.me... >>> I have a mast, rotor and yagi TV antenna on my roof. The antenna is >>> probably 15' feet above the roof. It has 12 or so large elements, and a >>> similar amount of smaller elements. There are three guy wires. It was >>> struck by lightning about eight years ago, and took out the rotor control >>> in the house. There was no apparent damage to the antenna it is not in use, >>> disconnected from the TV, but the antenna wire goes into the house. It is >>> easily the tallest structure around the house, that is, no trees accept a >>> tall pine about 80' away, which is close to the height of the antenna. >>> >>> About the end of August and to mid-Sept. we have occasional electrical >>> storms. We had a strong storm near our house 2 weeks ago. My question is >>> should I have the antenna taken down or somehow grounded. If the latter >>> what's a conventional way to do it? Copper wire from the base of the mast >>> down the side of the house to a ground pipe? The antenna is about 20' from >>> the end of the roof near it. I'm not sure of the material used for the >>> mast. It may be aluminum. >> >> IF you leave it up (which is probably the worse option) then I'd suggest you >> run copper wire from the TOP of the mast, all the way down. Ideally this >> 'down conductor' (as some call it) has no sharp bends in it and preferably >> no bends greater than 90 degrees. >> >> I'm not 100% sure what you mean when you say ground pipe, but I would >> connect the down conductor to a ground rod (10' long rod, steel or copper >> clad steel depending whether your soil eats up unprotected steel, 3/4" >> diameter, pounded straight down into soil until it's top is about a foot >> below ground). Ideally that rod is 2m (or 4m or more) away from your >> house's ground (be that a rod, underground metallic water pipe, or >> whatever). You could then connect the ground rod to your ground system with >> a #6 AWG bare copper wire. >> >> j >> >> >By pipe, I really meant about a six foot copper pipe, 1/2" or so. > >Yes, taking it down the antenna seems a sensible way to go. I'll get >the fellow who put it together many years ago to remove it. > >To Robert, a bad choice of words to Subject. > >By the way the roof peak is about 60' long, and a roof, lower, is about >35' long. > >So what's some simple way to protect us from being hit? Someone years >ago suggested four lightning rods strung out along the peak was a way to >go, with them all grounded. One end of the line along the peak would go > down the side of the house to the ground. > >So is there
Not about to jump into the leave it up or take it down discussion, but it probably does make a good lightening rod. Sharp points would be better to discharge the air before a strike can occur. If you have rock free soil an excellent method of putting down a ten foot rigid copper tube rod is to connect it to a garden hose and "wash" it down. Helps to cut the down end at a slight bevel but straight ends work too. Solder a heavy lead to it before you wash it down. Quest brand screw tightened compression fittings (you'll want an elbow) for plastic water tubing can interface with 1/2" copper and 3/4" garden hose and be easily removed once the rod is in place.
On Thu, 19 Sep 2013 22:54:56 -0500, "operator jay"
<oj@invalid.invalid> wrote:

> >"W. eWatson" <wolftracks@invalid.com> wrote in message >news:l1gbi0$4cq$1@dont-email.me... >> On 9/19/2013 7:13 PM, operator jay wrote: >>> "W. eWatson" <wolftracks@invalid.com> wrote in message >>> news:l1frgt$n2n$1@dont-email.me... >>>> I have a mast, rotor and yagi TV antenna on my roof. The antenna is >>>> probably 15' feet above the roof. It has 12 or so large elements, and a >>>> similar amount of smaller elements. There are three guy wires. It was >>>> struck by lightning about eight years ago, and took out the rotor >>>> control >>>> in the house. There was no apparent damage to the antenna it is not in >>>> use, >>>> disconnected from the TV, but the antenna wire goes into the house. It >>>> is >>>> easily the tallest structure around the house, that is, no trees accept >>>> a >>>> tall pine about 80' away, which is close to the height of the antenna. >>>> >>>> About the end of August and to mid-Sept. we have occasional electrical >>>> storms. We had a strong storm near our house 2 weeks ago. My question is >>>> should I have the antenna taken down or somehow grounded. If the latter >>>> what's a conventional way to do it? Copper wire from the base of the >>>> mast >>>> down the side of the house to a ground pipe? The antenna is about 20' >>>> from >>>> the end of the roof near it. I'm not sure of the material used for the >>>> mast. It may be aluminum. >>> >>> IF you leave it up (which is probably the worse option) then I'd suggest >>> you >>> run copper wire from the TOP of the mast, all the way down. Ideally this >>> 'down conductor' (as some call it) has no sharp bends in it and >>> preferably >>> no bends greater than 90 degrees. >>> >>> I'm not 100% sure what you mean when you say ground pipe, but I would >>> connect the down conductor to a ground rod (10' long rod, steel or copper >>> clad steel depending whether your soil eats up unprotected steel, 3/4" >>> diameter, pounded straight down into soil until it's top is about a foot >>> below ground). Ideally that rod is 2m (or 4m or more) away from your >>> house's ground (be that a rod, underground metallic water pipe, or >>> whatever). You could then connect the ground rod to your ground system >>> with >>> a #6 AWG bare copper wire. >>> >>> j >>> >>> >> By pipe, I really meant about a six foot copper pipe, 1/2" or so. >> >> Yes, taking it down the antenna seems a sensible way to go. I'll get the >> fellow who put it together many years ago to remove it. >> >> To Robert, a bad choice of words to Subject. >> >> By the way the roof peak is about 60' long, and a roof, lower, is about >> 35' long. >> >> So what's some simple way to protect us from being hit? Someone years ago >> suggested four lightning rods strung out along the peak was a way to go, >> with them all grounded. One end of the line along the peak would go down >> the side of the house to the ground. >> >> So is there > >Your reply looks to have gotten cut off. > >If I understand correctly you have a peaked roof on which the peak is >60'long, and if you rolled down the slope away from the peak, you would go >over an edge, and drop onto another sloped roof. This lower sloped roof is >about 35' long, and sloped in the same direction as the higher roof. Also, >I have been assuming a shingle roof. > >Yes, four lightning rods ("air terminals", probably about 20" tall each) >along the peak, with a conductor connecting them all, takes care of the >peak. Then, from the same end of the peak, two conductors could run down >the slopes from the peak to the edges of the roof (the conductors running >down from the peak would still be on top of the roof, but near the edge of >the roof). One conductor would go over the edge of the roof and down to a >ground electrode. The other conductor would go over the edge of the roof, >drop to the lower roof, run down the edge of that lower roof to a corner, >then go over the corner and down to a ground electrode. Those electrodes >should prbably be interconnected to each other, and to the house's ground. >The rods should be 2 or 3 feet out from the building. > >I don't recall for sure, but I think you could probably do without the air >terminals - the conductor running along the peak acts as an "intercepting >conductor" and takes the lightning hit.
I think you need the spiky rods pointing at the sky. The purpose of "lightning rods" in this sort of installation is not to conduct a hit, but to prevent it in the first place by providing a drain for charge build-up. (There is a neat high-school science experiment with a Van de Graaff generator, where you tape a thumb tack to the globe with the point outward... makes a definite "ionic wind" when charged up!) A system that is actually designed to conduct a strike (like the Empire State Building) needs monster buss-bar to handle the bazillion (or so) amps. <g> Best regards, Bob Masta DAQARTA v7.40 Data AcQuisition And Real-Time Analysis www.daqarta.com Scope, Spectrum, Spectrogram, Sound Level Meter Frequency Counter, Pitch Track, Pitch-to-MIDI FREE Signal Generator, DaqMusic generator Science with your sound card!
On 9/20/2013 7:15 AM, Bob Masta wrote:
> I think you need the spiky rods pointing at the sky. The > purpose of "lightning rods" in this sort of installation is > not to conduct a hit, but to prevent it in the first place > by providing a drain for charge build-up. (There is a neat > high-school science experiment with a Van de Graaff > generator, where you tape a thumb tack to the globe with the > point outward... makes a definite "ionic wind" when charged > up!) > > A system that is actually designed to conduct a strike (like > the Empire State Building) needs monster buss-bar to handle > the bazillion (or so) amps. <g>
Actually I just recently read a piece about how lightning rods work, and that one said that your explanation is the wrong one. They actually do catch lightning strikes, they don't discharge the cloud to prevent them. Bill
On 9/20/2013 8:15 AM, Bob Masta wrote:

> > A system that is actually designed to conduct a strike (like > the Empire State Building) needs monster buss-bar to handle > the bazillion (or so) amps. <g>
1.21 Jigawatts.