Cable and lightning protection

[yankees6161]

This spring I plan to move my antenna out of the attic and get it out side. I plan to use lmr400 cable about 75ft and a lightning arrestor. Should the arrestor be attached to the antenna or in line with the cable close to the antenna. I am using a L-Com hgv-906u antenna. Jefa tech has a good pric on the cable. Any one bought their cable? I also believe I should ground the arrestor to the existing ground at the electrical meter to my house. Is that correct? Any advice will be greatly appreciated

 

[mmckenna]

The lightning arrestor should go at the point where the coaxial cable enters the home.

The grounds all need to be bonded together, so, yes, the antenna ground and lightning arrestor ground need to be connected to the house ground rod.

 

[prcguy]

Jefa Tech coax will work fine and the lightning arrestor info above is correct. Just know that you will not really be protected from a direct lightning strike and the grounding is more for human safety to put the antenna system at the same ground potential as your house ground. If you stick a lone ground rod for your antenna at the far side of the house from the AC panel it can place some dangerous voltage on the antenna and coax compared to your existing house ground.

This spring I plan to move my antenna out of the attic and get it out side. I plan to use lmr400 cable about 75ft and a lightning arrestor. Should the arrestor be attached to the antenna or in line with the cable close to the antenna. I am using a L-Com hgv-906u antenna. Jefa tech has a good pric on the cable. Any one bought their cable? I also believe I should ground the arrestor to the existing ground at the electrical meter to my house. Is that correct? Any advice will be greatly appreciated

 

[yankees6161]

Does the antenna ground need to be anything special? Or can I just ground to the antenna mount? Grounding the arrestor at the point of entry I will need two cables and have to add about 25-30 feet. Looking at over 100 ft of cable at this point. How long is to long for cable length?

 

[prcguy]

You might want to look over NEC article 810 which covers antenna grounding. I believe #10 copper wire is the minimum size and from my satellite installer training days we try to keep the ground wire run from a coax grounding block or lightning arrestor to the AC panel ground under 30ft.

Does the antenna ground need to be anything special? Or can I just ground to the antenna mount? Grounding the arrestor at the point of entry I will need two cables and have to add about 25-30 feet. Looking at over 100 ft of cable at this point. How long is to long for cable length?

 

[KD7RJC]

Does the antenna ground need to be anything special? Or can I just ground to the antenna mount? Grounding the arrestor at the point of entry I will need two cables and have to add about 25-30 feet. Looking at over 100 ft of cable at this point. How long is to long for cable length?

You might want to look over NEC article 810 which covers antenna grounding. I believe #10 copper wire is the minimum size and from my satellite installer training days we try to keep the ground wire run from a coax grounding block or lightning arrestor to the AC panel ground under 30ft.

I'm in @yankees6161's boat myself, I'm looking at figuring out how to safely bring my radio coax into the house. I've been following a combination of Ward Silver's Grounding and Bonding for the Radio Amateur and the Motorola R56 standards document.

The latter document is several hundred pages with chapters covering everything from commercial radio installations with onsite generators and separate towers all of the way down to putting a roof-mounted antenna on structure that also serves other purposes.

The key takeaways I'm getting from these are first, there is no distinction between grounding for electrical safety, grounding for RF purposes, and grounding for lightning protection, and that lightning will take all available paths, and that second, all grounds must tie together in order to reduce the possibility of having uncertainty in what path is taken to ground and in having weird voltage differentials.

It also looks like in order to prevent the radio from becoming a pathway for lightning to find its way to earth that it's necessary to bring the electrical circuit to the same point of ground that coax for the antenna is grounded. The piece that I'm not yet sure of is a part number for the electrical supply protection device ("PLDO" in Ward Silver's book) in order to accomplish this. So if anyone wants to weigh-in on what sort of protection device would work best for this particular purpose I'm sure it would be helpful to many of us.

FWIW I've been working with a Citizen's Band Radio Service private LTE network professionally, I don't handle the RF side but Motorola R56 is the standards document that they're working-to for safe installation of up to 85' cell-site poles.

 

[mmckenna]

So if anyone wants to weigh-in on what sort of protection device would work best for this particular purpose I'm sure it would be helpful to many of us.

I'm no expert in this field, but what I see at the sites I lease to cell carriers is usually something along the lines of this:

Rayvoss A

Strikesorb, the high surge capacity protection element inside Rayvoss repetitively absorbs and dissipates excess energy from surges.

www.raycap.com

It'll be installed at the main panel to dump any surges to ground. The concern is the surge coming from either direction, the site, or via the incoming power lines.

FWIW I've been working with a Citizen's Band Radio Service private LTE network professionally, I don't handle the RF side but Motorola R56 is the standards document that they're working-to for safe installation of up to 85' cell-site poles.

You probably meant Citizens Broadband Radio Service. We're talking with Federal Wireless about setting up private LTE on CBRS at work.

R56 is pretty much the bible when it comes to this stuff. I've seen other LMR manufacturers reference it in their install guides. No reason for anyone to rewrite what already exists.

 

[KD7RJC]

I'm no expert in this field, but what I see at the sites I lease to cell carriers is usually something along the lines of this:

Rayvoss A

Strikesorb, the high surge capacity protection element inside Rayvoss repetitively absorbs and dissipates excess energy from surges.

www.raycap.com

It'll be installed at the main panel to dump any surges to ground. The concern is the surge coming from either direction, the site, or via the incoming power lines.



You probably meant Citizens Broadband Radio Service. We're talking with Federal Wireless about setting up private LTE on CBRS at work.

R56 is pretty much the bible when it comes to this stuff. I've seen other LMR manufacturers reference it in their install guides. No reason for anyone to rewrite what already exists.

Yeah Citizens Broadband Radio Service is what I meant. I have too many TLAs and BFLAs floating around in my head these days.

I don't have experience with Federal Wireless, but we had Motorola implement ours and right as we're almost done they're ready to wash their hands of it, preparing to outsource it to Bearcom. I'm a little pissed off since Bearcom wants to yank out a bunch of equipment that we just paid for in order to rework it their way.

OT I know. Sorry.

 

[CanesFan95]

Does the antenna ground need to be anything special? Or can I just ground to the antenna mount? Grounding the arrestor at the point of entry I will need two cables and have to add about 25-30 feet. Looking at over 100 ft of cable at this point. How long is to long for cable length?

Think of the lightning arrester as basically a barrel connector, except it has a 3rd connection point to attach your thick copper wire which is run straight down to the ground rod. The arrester should be located outside the structure just before the coax enters the structure, and you'll need to seal everything against water. So you don't necessarily need a longer coax run or another piece of coax. You can use the same 75', except you'll need to cut it, add connectors, and then insert the arrester like a barrel connector.

 

[John_S]

The only foolproof lightning protection is to unplug...only connect when needed. A direct hit on an antenna or tower can easily blow right by an inline arrester, mostly because lightning is very fickle about it's path to ground and has a mind of it's own.