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Worse Case Scenario - Lightning Strike?

T

The Jerk

Active Member
May 6, 2008
647
66
38
Reading, PA
Getting ready to put up two antennas...got some questions on lightning:

*Can you protect from a strike? What is needed to protect a typical house-mounted antenna/coax setup?

*What does everyone do during a storm? What steps do you take?

*Is it something that you can even protect from? Do you even worry about it?

I'd really like to hear peoples' thoughts on the subject...read stories where a lightning strike on a shack's antenna actually burnt the house down, and I really don't want to have that happen!!!
 

i have my antenna insulated from the mast and dont use a ground wire . i also disconnect my coax at the first sound of thunder or it looks like a good storm coming in or im gonna be away for a night or more . and i dont put my coax in a glass jar , LOL . i dont have noise issues with my good radios , but some folks say they have reduced noise issues using a earth ground . i figure regardless of earth ground that if lightning hits the antenna directly that it , the coax and anything connected to the coax is fried .... and that keeping the antenna isolated from the mast/earth ground keeps all my signal up in the air and elimnates them (mast/ground wire) from radiating as part of the antenna system .
 
You can not protect AGAINST a strike, but as Booty says, you can take steps to reduce the damage incurred when you do take a hit. I myself don't worry about it much, but I do disconnect my equipment when storms are near. But remember, lightning can and does occur on clear, sunny days, too.
 
*Can you protect from a strike? What is needed to protect a typical house-mounted antenna/coax setup?

You can increase protection from a lightning strike, but you can not completely prevent or protect from one (or a near one). Closest you can get is to use a grounded antenna like the broadcast stations do. That is not as simple as it sounds.


*What does everyone do during a storm? What steps do you take?

Except for very serious situations, I turn off the radio and ground the antennas through a remote switch. That helps, but is certainly not anywhere near a complete protection. That lightening can get to you from the ground side too.


*Is it something that you can even protect from? Do you even worry about it?

Lightning isn't something you can protect from completely without completely disconnecting your radio and putting it in a grounded metal case away from all openings to the weather. I have a lot of trouble seeing anyone do that!

One of the things required is a very good ground radial system. Sorry, ground rods are no protection unless there are -quite- a few of them connected properly. That "quite a few" is in terms of dozens, not single digit numbers.
'ICE' has a fairly good description of an adequate ground system. You do have to keep in mind tht they are a retail business and want to sell you stuff. The National Electrical Code describes grounds for lightning protection. It's the standard, so read it. That will give you a starting point.
- 'Doc
 
I believe the NEC indicates two 8-foot rods a minimum of 8 feet (or was it 14 feet) apart? I actually need to add a ground rod to my current house that *should* have had the second rod installed when it was built. Should I, or should I not, tie into the house's ground system? I have no issues running some solid copper ground wire to the existing rods. I already have the second ground rod, just need time to get it driven and the wire ran to the box.

My biggest fear is that I'm not always there and that the radios could potentially be on and connected during a storm. We are about the highest thing around, short a cell tower about a mile off...no trees or other big structures taller than the house or the proposed antenna within several hundred feet.

I know one of the houses near me got zapped a couple months ago, it fried all the CATV coax in their house.
 
How do brodcast stations and cell phone towers do it? they stay connected when lightning storms are going on or does someone stay on standby to unhook the coax when it happens? I even heard that they get multiple strikes and still keep going.

They must have some kind of good setup.
 
Broadcast stations very seldom (if ever) 'disconnect' during storms. Instead, they inductively shunt their antennas(s) to ground. A coil of high impedance (at their broadcast frequency) is connected from the 'center conductor' directly to their ground system. Anything NOT on their frequency sees that coil as a direct short (low resistance) to ground and takes it instead of through the transmitter. In most cases, the ones listening tothat broadcast station never know there's been a lightning hit.
One of the properties of inductance is that it's frequency 'sensitive'. By picking the 'right' inductance (size of coil), the transmitter doesn't 'see' it (very high 'resistance'), but stuff not on that transmitter's frequency does 'see' it as a very low 'resistance'. Lightning is going to take the path of least resistance if possible, so, goes to ground.

All that isn't very specific, or exact, and I meant it to be that 'general' in nature. It's a very good idea to find someone who is very familiar with doing that sort of thing to explain it better than I can. I'm way too lazy to refresh myself enough about it to explain it well. Besides, you need to learn to do it anyway! (Howz that for an excuse??)
- 'Doc
 
I disconnect all coaxes to all 6 of my antennas and they go outside the house and get tucked away where they stay dry aswell. Some dont worry about lightning I DO!! and always will for that matter because it is kind of scary when you see what lightning can do.

I know equipment can be replaced and thats what as people say insurance is for but some things like my house, wife, kids and pets are not replaceable so I just feel better knowing that my antenna coax isnt bringing lightning into the house.

I have had a horrible summer as far as radio due to outrageous amout of storms and rain we been having we been getting hit with storms atleast 4 times a week here in Central Wi and they include heavy lightning but we have hasd really hot and humid weather so thats what brings the storms on.

All in all you cannot copletely save yourself from a direct his but I just feel better knowing that our family radio hobby is not going to contribute to a huge loss of a house or life. Its a pain at times bringing in the coax just to see that there is storms once again coming 2 hours after I just dragged everything back in.

I just often have to think about it and remind myself that its all part of the price I pay to have my hobby of radio play. There are alot of good reads on this subject if you do a search on the net. Good luck with everything and just do a little reading and that alone will educate you on lightning and you will get your asmwers to your questions and also learn a whole lot more.
 
I was home during a direct hit on my tower. My neighbors saw the strike, it split just before hitting my tower one leg hit the ar 10 on top and another leg hit the service entrance. Lost the ar10, rotor,cb I had at the time, feed line was trashed, most all electronics that was plugged in was history, set the fuse pannel on fire. I was lucky I was home or I would have lost my house. The tower was grounded as was the radio equipment but they were not bonded together. Now on the new tower I have one 8' rod for each leg of the tower inside a grounded delta all of which is bonded to the service entrance ground rod. The feed lines go through ICE surge protectors which also bleed off any static charge from the tower.I have got in the habit of disconnecting the coax when I am through talking for the evening. Its a pain but this has worked so far. I also disconnect all power supplys from the wall sockets and switch the switch boxes to ground. Is seems like a lot but I live in a bad spot for lightning.
 
So what I gathered from reading...

NEC requires that the antenna mast needs to be bonded to its own grounding rod using a minimum #10 wire, and that "grounding system" is also bonded to the house grounding system. The coax needs a grounding block also connected to the antenna's ground rod.

I understand this is to help prevent a lightning strike, as well as dissipate energy from a nearby strike; but not protect from a direct strike.

So, my plans are:


  • Drive an 8-foot Cu-clad ground rod near the antenna's mounting point (directly under it mounting place on the roof).

  • Connect the base of the antenna to the ground rod using at least #10 Cu wire.

  • Connect the grounding rod to the house grounding system using #6 solid Cu wire.

  • Run the RG-6QS to ground level, and bond a grounding block to the grounding rod, then return the coax to the send floor where the radio resides. (this will add over 50 feet of coax to my run, attenuation?)

  • Hope for the best?

Anything I'm missing?

I am now thinking of only installing the scanner and its antenna, which I was planning on using a 102" whip on a "L" bracket (because of the ferocity of the winds at this new place). It could be 100"s taller than the peak of the house depending on where I mount it.

My main concern is turning the house into a lightning rod.
 
A lightning bolt has typically traveled a couple thousand feet or more, from a cloud to what it perceives as the "path of least resistance" to earth. If it travels that far through an almost perfect insulator (air), don't even think of doing anything to prevent it from going anywhere it wants to. You won't succeed.

Radio and TV stations don't go off the air and disconnect their antennas whenever a storm is forecast. Florida would be radio silent if they did. What the broadcasters do is install their antennas correctly.
 
Worst case scenario of a direct lightning strike can be summed up in one word,Death,if you avoid that you are very very lucky.

As others have said there is nothing you can do to tame the power of mother nature if she decides to shit all over you,its a risk we all take every day we breath her precious air.
 
The Jerk said:
So what I gathered from reading...

NEC requires that the antenna mast needs to be bonded to its own grounding rod using a minimum #10 wire, and that "grounding system" is also bonded to the house grounding system. The coax needs a grounding block also connected to the antenna's ground rod.

I understand this is to help prevent a lightning strike, as well as dissipate energy from a nearby strike; but not protect from a direct strike.

So, my plans are:


  • Drive an 8-foot Cu-clad ground rod near the antenna's mounting point (directly under it mounting place on the roof).

  • Connect the base of the antenna to the ground rod using at least #10 Cu wire.

  • Connect the grounding rod to the house grounding system using #6 solid Cu wire.

  • Run the RG-6QS to ground level, and bond a grounding block to the grounding rod, then return the coax to the send floor where the radio resides. (this will add over 50 feet of coax to my run, attenuation?)

  • Hope for the best?

Anything I'm missing?

I am now thinking of only installing the scanner and its antenna, which I was planning on using a 102" whip on a "L" bracket (because of the ferocity of the winds at this new place). It could be 100"s taller than the peak of the house depending on where I mount it.

My main concern is turning the house into a lightning rod.
Click to expand...





My question was, is this a correct installation.
 

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