grounding.... question..

[Monster75]

first off i know lots of questions, but i am still new and trying to learn as much as i can and do things the right way first time around......

ok i got my LMR400 cable in today 30 feet long... my antenna is in the attic walk in attic no insulation on the roof just ply wood and shingles... not that i have LMR 400 i plan on moving my antenna outside and attach it to the side of my house via window i have in the attic easy for me to hang up.. just reach out the window and attach it.. i will then take my LMR 400 and run it from the antenna down the side of the house and then into the house wall and straight into my scanner..... what is the best way for me to ground this???? i am not sure what to do.. what i do have right now is rg6 cable going from the antenna to a spilter then other side of spliter more rg6 cable going into the wall and hooked on a wallplate.. then inside the house a cable runs from wall plate to my scanner... on the splitter out side i have hooked up a cooper wire to a ground rod... i wanna make sure i can ground everything right this time.... so any help would be great......

i was thinking of getting this Amazon.com: AIR802 Coaxial 50 Ohm Lightning or Surge Protector… and just ground this to the rod i have in the ground and call it safe...

 

[rfradioconsult]

Unless your outside antenna is the highest object within a couple of hundred feet, you don't need to take a lot of precautions. You didn't specify how long your ground rod is, unless it's at least 8' it provides no useful purpose, for electrical safety install a 8' ground rod close to where your coax enters the wall, grab a short piece of about #10 stranded wire, strip about 2 inches off the coax and expose the braid, remove about 12" of insulation off of the wire and wrap the wire around the bare coax shield tightly, then apply a couple of layers of good electrical tape extending about 6 inches both sides of the bare shield, connect the other end of the wire to the terminal on your ground rod. Remember to disconnect the coax when lightning is about.

You will get a LOT of advice on lightning protection, just remember an antenna does not attract lightning anymore than that old 75 year old oak tree in the backyard.

 

[stryker106]

here's another option
"HT-GK400" < put that in google
its a Grounding Kit for 400 Series Coax Cable
that I am thinking of getting.

 

[Monster75]

here's another option
"HT-GK400" < put that in google
its a Grounding Kit for 400 Series Coax Cable
that I am thinking of getting.

hmm i might check into this.... but also my do the same thing as the member up above said but just wraping the some #10 around it and attaching to the ground...

 

[benbenrf]

Unless your outside antenna is the highest object within a couple of hundred feet, you don't need to take a lot of precautions. You didn't specify how long your ground rod is, unless it's at least 8' it provides no useful purpose, for electrical safety install a 8' ground rod close to where your coax enters the wall, grab a short piece of about #10 stranded wire, strip about 2 inches off the coax and expose the braid, remove about 12" of insulation off of the wire and wrap the wire around the bare coax shield tightly, then apply a couple of layers of good electrical tape extending about 6 inches both sides of the bare shield, connect the other end of the wire to the terminal on your ground rod. Remember to disconnect the coax when lightning is about.

You will get a LOT of advice on lightning protection, just remember an antenna does not attract lightning anymore than that old 75 year old oak tree in the backyard.

Whoooa, rfradioconsult - this is a new one for me.

I do not want to sound presumptous, and I am not wanting to challenge the advise you have provided to Monster75 - but is stripping back the sheath on the coax just prior to entry through the wall - to implement an earth connection to the screen an accepted standard and/or practise to implement an antenna/coax earthing connection?

I can see the straight direct path logic in what you are proposing (couldn't get it any shorter, straighter or my direct than that for sure) - but the implementation is not a practise or standard I am familiar with - there again, I am not familiar with the USA rules/regs and standards.

Let me share with you how we would do it in the Uk, and may other places in Europe.

If the antenna was external, the standard I would implement would be a dedicated copper strap from the antenna, down the side of the building to earth - meaning a +/- 8' x 1.2" copper rod, or similar (I forget the exact dimensions, but whatever they were I know I always spec'd a 2m x 15mmm plus rod, if only because I remember that exceeding the the min spec and we had a warehouse full of copper rods just that size!.

Splicing an earth to the outer screen is something I only ever done once in over 20years - and was only because the spooks were up to some or other mischief and were trying to get as close to the chassis of the receiver inside the building to monitor leakage - but otherwise, if I ever carried out an earth like that it would never have been signed off.

Anyway. like I said, I am not familar with regs stateside, or practises - so I do not want to come across as questioning the advise you have offered here, just to say its a) a new one for me and b) not how an earth woul dbe implimented in the UK.

Other than that, the rest of what you have said and the points you noted - yup, can relate to them and recognise them - much the same practise throughout most of Europe.

Good point re: the comparison between the antenna and the tree.

 

[Viper43]

To be honest I am not sure I like the ideas rfradioconsult gives either. If it were me, I'd ground the coax up top and down below using something like this: Coax Grounding Bracket, 1-1/2 inch V-bolt

Also the comment about the tree isn't true either. I have witnessed lightning strikes on trees and towers. One tree strike in particular in my own yard surprised me as it hit between two taller trees that were 6 feet on either side of the tree that took the strike. Those trees were 8 to 10 feet taller than the one hit. It split the tree in half. Then it took out the well pump a 100' away.

I also saw a tower that was 30' tall take a hit instead of the 40' and 50' trees that were 30' to 60' feet from the tower. The tower had one single ground rod (8') the coax had a seperate ground where it entered the house. The coax was burned and so were all the radios. The room caught fire but the house was saved. The cement that held the tower exploded and the tower was split in numerous places.

Another tower that took a hit had less damage but it had all 4 legs on a seperate ground. The coax was grounded top and bottom with similar grounds as my link above. Each of those connectors had a seperate ground rod as well. The guy wires also had a seperate ground rod. The owner had a disconnect and polyphasers .... had to replace the antenna and coax but nothing else.

So height doesn't really matter when dealing with lightning, it's going to hit where it wants to, and I wouldn't take a chance that my tower isn't going to take a hit. The antenna is at 65' and it's still lower than the surrounding trees in the vacinity, still would trust the tower won't get hit.

V

 

[Monster75]

To be honest I am not sure I like the ideas rfradioconsult gives either. If it were me, I'd ground the coax up top and down below using something like this: Coax Grounding Bracket, 1-1/2 inch V-bolt

Also the comment about the tree isn't true either. I have witnessed lightning strikes on trees and towers. One tree strike in particular in my own yard surprised me as it hit between two taller trees that were 6 feet on either side of the tree that took the strike. Those trees were 8 to 10 feet taller than the one hit. It split the tree in half. Then it took out the well pump a 100' away.

I also saw a tower that was 30' tall take a hit instead of the 40' and 50' trees that were 30' to 60' feet from the tower. The tower had one single ground rod (8') the coax had a seperate ground where it entered the house. The coax was burned and so were all the radios. The room caught fire but the house was saved. The cement that held the tower exploded and the tower was split in numerous places.

Another tower that took a hit had less damage but it had all 4 legs on a seperate ground. The coax was grounded top and bottom with similar grounds as my link above. Each of those connectors had a seperate ground rod as well. The guy wires also had a seperate ground rod. The owner had a disconnect and polyphasers .... had to replace the antenna and coax but nothing else.

So height doesn't really matter when dealing with lightning, it's going to hit where it wants to, and I wouldn't take a chance that my tower isn't going to take a hit. The antenna is at 65' and it's still lower than the surrounding trees in the vacinity, still would trust the tower won't get hit.

V

hmmmm interesting info thank you for that.. i have yet to put up my stuff as i am still trying to determine the best route to go for grounding, wiht out effecting my LMR400 and loss of DBs..

 

[rfradioconsult]

Reread my post, in a home environment it is difficult and expensive to protect against a direct strike, my advice is for providing an electrical ground, not a lightning ground. If you get a chance to inspect a commercal radio site built in the last few years you will see what it takes to survive a direct strike.

Benbenrf yes I am/was familiar with the ETSI standards, back 20 years ago I was a Senior Project Engineer for the first GSM network (D2) in Germany a partnership between Mannesmann and PacBell, later I worked for L.M. Ericsson in developing their GSM product for the U.S. market.

 

[Viper43]

Reread my post, in a home environment it is difficult and expensive to protect against a direct strike, my advice is for providing an electrical ground, not a lightning ground. If you get a chance to inspect a commercal radio site built in the last few years you will see what it takes to survive a direct strike.
.

Funny but you even said lightning in your comments. And the electrical ground is ALSO part of the lightning protection, whether intended or not. It's not THAT expensive to protect your equipment from lightning, especially at the cost of todays radios. Add to that the cost of a home. I may have to replace parts but I won't have to replace the shop or house.

V

 

[knightrider]

Basically all this boils down too, is that the "average" radio buff cannot survive a direct hit. Many commercial installs can't either. Dealing with lightning, is a "crap shoot" at best, even with the best engineers. There are many good installs that survive a hit, but several hundred to thousands of dollars have been spent, something the "average" radio buff doesn't have. The OP, has a few feet of coax, an antenna that was inside, and now he wants to use it outside. If he has the extra funds, and wants to wait a bit, something like a Poly-Phaser arrestor might be his best bet for his install. If he had the funds to do the big stuff, one of you guys would already be there doing it for him, and getting the money for it. The idea of stripping the insulation back is as good as the DXE-CGB-150 Coax Grounding Bracket, but on a less expensive note. I would suggest one of the silicone sealants to assist the electrical tape in weatherproofing it though. The other option would be to make a run from the antennas down the house, as straight as possible, and to the suggested 8' ground rod as well, as the tap onto the coax. I have trees all around my house, they are taller than my towers, and are Pine. My towers have my VHF and UHF beams on them for Ham, and also have verticals or groundplanes on the very top for the same. My scanner antennas are mostly homebrew, and mounted about half way up. My reception is usually over 75 miles with them. My advantages??? I have a cell tower about 1/4 mile away. I have two power distributions stations about 1/2 mile away. Each of these seem to absorb the lightning, especially the power stations, as they have a BIG lightning rod sticking up in the middle of each system. Oh, and right across the highway, is a set of UP railroad tracks, and they DO get hit regularly, when we do get storms (Been REAL dry lately). I still use precautions, but have lost the front end on a couple of rigs, due to the "static discharges" or build ups nearby. Not knowing what is in the direct vicinity of the OP, what his house is actually made of, if there are other towers nearby, or as in my case, railroad tracks, or distribution sites, he might have some built in diversions to direct strikes. At the very least, if there is a lot of lightning, there should be an arrestor inline...
Knightrider.....

 

[Monster75]

hey knightrider.. my house was built in 1943, wood shingles.. 3 story house walk in attic with nothing up there no electrical stuff nothing just wood...lol... i have rail road tracks about two blocks from my house along with a metal recycling place also that recycles metals crushes cars and loads the metal on trains.... other then that the closes cell phone tower near me is about 2 miles away.. same with 911 center thats about 3 miles away from me and the fire station 2 is at end of my street....hope that helps... i may have figured out what i wanna do but will still listen to all

 

[rfradioconsult]

If you are considering the lightning arrestor you mentioned in your original post, I was finally able to find the specifications and it has an N male and N female connectors which unless you are experienced with install the N connector can be tricky; also this is a gas tube discharge design and fires at 90 volts, so the question is will your radio withstand 90 volts on the antenna input without damage. Good luck on your project.

 

[NoCoFire]

Good Luck

Many, many, many people have their opinions on what works best for lighting protection. Above this post is just a sprinkling of what is out there. I too have installed a new system and wanted to do it right. My location is not in the lighting capitol of the world in fact we are probably on the low end of lighting activity but it takes only one nearby strike or other static buildup to ruin all your stuff. Before spending my hard earned money on equipment I wanted to do it right so I turned to different forums like this one and was disheartened by all the opinions that people offered and how quickly one poster would be debunked by another – it was frustrating to try and get an honest answer. Here you go: Lightning is completely unpredictable and can strike almost anywhere. You and I probably cannot afford a commercial system that MAY protect their equipment (well maybe you can but I know I cannot). In my humble opinion and I believe this: my equipment will not survive a direct strike and yours will probably not either.

So here is what I did. I consulted with an electrician and another friend who is also an electrician that because of his age now inspects commercial electrical work. They both told me to consult the National Electric Code article 800 to 830. This tells you, at a minimum, what you need to do to properly ground your antenna and coax. You should never drive a ground rod unless you know what you are doing in the first place. Putting a ground rod into the ground and not properly bonding it to your house ground is asking for big trouble, this is why: your coax is connected to your unbonded grounding rod that you just installed and you have a nearby lightning strike or some other static buildup on your antenna (you can get static buildup from wind!), this same coax is also connected to your radio that is plugged into your house current. The difference in impedance from the coax ground compared to the house ground is what may fry your equipment. Grounding rods need to be bonded together. I just did this the correct way and it cost me maybe $20. At Home Depot a 5/8 grounding rod cost $10, the coax grounding block at Lowes cost $5, the clamp for the rod cost $5 and some #8 from the antenna mast I had already and the #4 that bonded the grounding rods I also had (be prepared #4 can be from .90 to $1 per foot). This is a very small price to pay especially if you do get hit and the insurance company sends an investigator you will at least have proof that your system was wired and properly grounded to Nationally Recognized Standards – that your local building codes probably already require. BTW – I still unplug and unscrew all of my electronics when a storm is approaching just to be safe. Go read a book and enjoy the storm, or use your handheld battery operated scanner with the factory antenna!

1. Remember everyone has an opinion, including me, and you should continue to do your research.

2. Nothing you can do will protect you from a direct strike.

3. Lightning is completely unpredictable and may not go after the highest thing – it is looking for the easiest path to ground.

 

[Monster75]

Many, many, many people have their opinions on what works best for lighting protection. Above this post is just a sprinkling of what is out there. I too have installed a new system and wanted to do it right. My location is not in the lighting capitol of the world in fact we are probably on the low end of lighting activity but it takes only one nearby strike or other static buildup to ruin all your stuff. Before spending my hard earned money on equipment I wanted to do it right so I turned to different forums like this one and was disheartened by all the opinions that people offered and how quickly one poster would be debunked by another – it was frustrating to try and get an honest answer. Here you go: Lightning is completely unpredictable and can strike almost anywhere. You and I probably cannot afford a commercial system that MAY protect their equipment (well maybe you can but I know I cannot). In my humble opinion and I believe this: my equipment will not survive a direct strike and yours will probably not either.

So here is what I did. I consulted with an electrician and another friend who is also an electrician that because of his age now inspects commercial electrical work. They both told me to consult the National Electric Code article 800 to 830. This tells you, at a minimum, what you need to do to properly ground your antenna and coax. You should never drive a ground rod unless you know what you are doing in the first place. Putting a ground rod into the ground and not properly bonding it to your house ground is asking for big trouble, this is why: your coax is connected to your unbonded grounding rod that you just installed and you have a nearby lightning strike or some other static buildup on your antenna (you can get static buildup from wind!), this same coax is also connected to your radio that is plugged into your house current. The difference in impedance from the coax ground compared to the house ground is what may fry your equipment. Grounding rods need to be bonded together. I just did this the correct way and it cost me maybe $20. At Home Depot a 5/8 grounding rod cost $10, the coax grounding block at Lowes cost $5, the clamp for the rod cost $5 and some #8 from the antenna mast I had already and the #4 that bonded the grounding rods I also had (be prepared #4 can be from .90 to $1 per foot). This is a very small price to pay especially if you do get hit and the insurance company sends an investigator you will at least have proof that your system was wired and properly grounded to Nationally Recognized Standards – that your local building codes probably already require. BTW – I still unplug and unscrew all of my electronics when a storm is approaching just to be safe. Go read a book and enjoy the storm, or use your handheld battery operated scanner with the factory antenna!

1. Remember everyone has an opinion, including me, and you should continue to do your research.

2. Nothing you can do will protect you from a direct strike.

3. Lightning is completely unpredictable and may not go after the highest thing – it is looking for the easiest path to ground.

thank you for that input i still have yet to put it all up i am still researching but your post helped alot also. so thanks for the info.. i been reading up alot on what i can do and best option... i can am like you and can not afford a top of the line direct strike system..
and i do have a home depot near me..... thanks

 

[TheJerk]

So what is the general conclusion...ground based on NEC requirements?

 

[NoCoFire]

Nec

So what is the general conclusion...ground based on NEC requirements?

TheJerk,

I did my system according to the NEC. But from what I understand the NEC is a minimum standard and there is no reason you could not go beyond those recommendations. Personally I like the polyphasers and think they are a good idea. I just have not installed them yet and am using a simple coax grounding block made by Ideal. But when I want to install them I will only have to replace the coax grounding block with the polyphasers. Should be simple.... but you know how that goes.

-NoCoFire

 

[CalebATC]

To tell you the truth, my antenna doesnt have ground even connected to it! But then again, it is on PVC. But is is pretty high up, and the highest thing around for miles. Getting ready to take it down to pack it up!

 

[Monster75]

wow..... how come you packing it up you moving?????? i have heard a few people say they dont ground there antennas..

 

[radioman2001]

There are 2 trains of thought on grounding. No grounding, or minimal grounding. If you are the highest object in the area, you can actually induce the lightning to go to your antenna instead of someplace else. If you provide a good path for lightning it will always pick that path over a less than good path.
There are a few homes in my area that sit along a ridge line over 600 ft above the average ground height. Some had professional lighting rods installed. Most of those homes now have had them removed. The last strike into a home I investigated with my FD the owner stated that he had the lightning rods removed, because he averaged 6 to 10 strikes a season after having them installed. Once they were removed he was back to 1 strike every 2 to 3 seasons. My thought is to give the lightning someplace else to go. A tower with a good grounding system away from your home is one way, or even a lightning rod stuck up in a tree away from your home. Following the NEC is a good start.
As far as grounding your coax, use a PolyPhaser. Minimal loss and will help send most if not all of the lightning energy to a good grounding rod.
BTW there is no tried and true method for lightning grounding, but I am in the school of providing a path if a direct hit occurs, but not too good as to become the preferred path.

 

[TheJerk]

TheJerk,

I did my system according to the NEC. But from what I understand the NEC is a minimum standard and there is no reason you could not go beyond those recommendations. Personally I like the polyphasers and think they are a good idea. I just have not installed them yet and am using a simple coax grounding block made by Ideal. But when I want to install them I will only have to replace the coax grounding block with the polyphasers. Should be simple.... but you know how that goes.

-NoCoFire

From what I remember reading of the NEC (assuming the antenna is "house mounted"):

...the mast should be bonded to a dedicated grounding rod using a minimum 10ga wire.

...the grounding rod should be bonded to the house grounding system using 6ga copper wire.

...a shield ground should be used on the coax.

Is this correct? The PolyPhaser would be above and beyond NEC, correct?

I was thinking of mounting a 102" whip on the ridge of the house because of the winds at this location...but I'm reluctant to now, since it is the highest location within 300 feet. I am actually thinking I may go back to an original plan and install a short pipe "tip up" mast/tower...to get the antenna off the roof.

I have an ST-75 (I think that's the model?) and I know there is no way it will survive the winds that come through here (with the storms)...the reason for a simple SS whip idea.