How is your A-99 grounded ?

[big daddy d]

Taking grounding advice

[MDYoungblood]

Grounding your antenna is just attaching the ground wire to the mast of the antenna and running it to a rod in the ground. The first thing you need to do is check the local electrical codes, they tell the minimal size wire to and how it needs to be installed, than like everything else think bigger. The 8ft ground rods and the attaching hardware can be found at any hardware store, the big names are the best to find them. How and where your antenna is mounted determines what you will need. Wire size is specified in the code, go larger, remember it is being used to take a direct lightning strike and transfer it into the ground. You also need an arrestor on the coax before it enters the house and the wire to the ground rod. Buy a good one. If you use the "Advanced search" you will find boo coo info on grounding and I am sure others will jump in on this topic.

One thing to note is it will not save your equipment or house from damage but makes life a lot easier went filing an insurance claim.

3's

Greg

[shaggy7705]

How is your antenna setup? Is on strapped to your chimney? on a tower?

[big daddy d]

The antenna is on a metal mast. I have a metal pole in the ground about 2 feet. The antenna mast is placed aver the pole that is in the ground. It is a force fit.The mast is attached to the eve of the house about 18 feet up.

['Doc]

Your antenna doesn't require an RF ground. that 'ground' is a safety ground, lightning etc. The best advice I can think of is to read the NEC, National Electrical Code, and go from there. All local codes or regulations are based on the NEC. There's nothing simple about safety grounds. Count on a -good- one being more than you want to mess with. But the alternative is almost always 'messier'.
- 'Doc

[dirtyjob]

as doc stated

[8fiveO]

Lightning isn't going to attract to a fiberglass antenna. However, the a99 has aluminum at the bottom I would think the best is wrap top of your mast with electrical tape and clamp antenna to it, then ground the mast.

[MDYoungblood]

Hi 8fiveO,
One of the reasons they make the mounting area on the A-99 or any fiberglass antennas is to make contact with the mast to complete it's grounding. It that wasn't the case than the manufacturers would make the antennas completely out of fiberglass. Also the shell may be fiberglass but there is still a metal wire inside. There is a lot of good information on the forum about grounding, check into it.

3's

Greg

['Doc]

Lightning doesn't have any preference as far as metal/wood/dirt/whatever. It is attracted to electrical charges no matter where/what they happen to be concentrated in. If a large'ish electrical field happens to be in a fiberglass thingy, that's where lightning is attracted to, where it will try to make contact and equalize charges with (if that makes sense). The way to protect something is to not let an electrical charge build up in that 'thing'. To either prevent that build up of to dissipate it before it get's to 'large' to handle. The 'other' way of doing it is to give that charge a path to something to dissipate it without going through and destroying the stuff you don't want destroyed. I don't think there's any way of preventing a build up of charges, but there's ways of dissipating it so it only 'cooks' worms instead of YOUR stuff. Those ways always mean more work/effort than a simple 'lightning' arrestor. It means finding or making something that can handle that electrical charge easily. It amounts to, "There ain't no simple, easy way". The most you can count on is that it will be a -practical- means for you. Then you take your chances (and hope 'Momma Nature' likes you a little bit, you know?).
- 'Doc

[Daveman927]

I agree with Doc, Lighting strikes where lighting strikes.
I do happen to work for a commercial electrical company and i happen to own a NEC book.
For the ground rod they come in 3 different diameters 1/2", 5/8", and 3/4" and two different lengths 8' and 10'. I would requiremend 5/8" x 8'. We typically dig a 1' to 2' deep hole and drive the rod in and cover it up. You want to rod to be a minmum of 1' below finish grade. They make special ground clamps for these rods as well. You want your clamp to be the same diameter of the rod and on the outside of the clamp there is a hole for you to stick your copper or aluminum ground in and a screw to tighten it. you want to put the lamp at the top of the rod and cover it completely with dirt. Now for your fround wire size.
You want to messure from the bottom of your antenna to where your putting your ground.
less then 35' use awg19 aluminum alloy or awg20 copper clad
35' to 150' use awg14 aluminum alloy or awg17 copper clad
more then 150' awg12 aluminum alloy or awg14 copper clad
Above is whats required of antenna grounds. I would say stay with the copper and you are not required to have a insulated ground.

Hope that helps,

73's

['Doc]

As I was asked recently, are you sure about those wire sizes used for safety grounding?
- 'Doc

[Daveman927]

Well if you would like to go all out then you can run 4/0 and larger down the mast. Your better off cad welding your ground conductor to the ground rod if you go that large and i would go up to a 3/4" x 10' rod. Reguardless the lightning is going to travel down the mast. Your antenna will be fried as well as the coax. As far as a requierment per NEC for antenna grounding yes those will be the minimum. If you would like to go with a full lightnig protectiong system by commercial means then buy 3 ground rods make a ground loop connecting all three ground rods (rods must be a good 5' below grade) and then run up the mast. Reguardless of which method your using your antenna will be gone as well as the coax. Also i would unhook your coax from your radio if you would like to be able to talk on that again. Generally we dont worry about lightning protecting untill you a get a structure thats 50' or taller. NEC reads as i posted in the last message. The choice is yours. Go all out spend lots of money on grounding or meet the minimum requierments. Either way when it gets hit by lightning, that antenna will be no more. as long as you can show your insurance person that your grounded to the minimum then your covered.

---

Thursday, 14 March 2013, 10:04 AM

If you want to be on the safe side and still meet NEC code go with #10 or #8. anything bigger then that is not necessary. 1/2" or 5/8" x 8' ground rod will be perfect.

['Doc]

We must have different versions of the NEC. Of course, none of this pertains to commercial power systems so I'm sure there's a difference there. But I've never seen any wire size quoted that small before. Or seen a ground on a power pole that small.
- 'Doc

[Daveman927]

NFPA 70. Now i dont have NFPA 780 which goes in alot more detail with lightning protection but the NFPA 70 covers grounding bonding protecting as well as amateur transmitting and recieving stations for grounding and bonding and lighting protction.

As far as the wire sizes stated earlier (i'll give it to you) they were more for operational purposes. I will attach a photo to show how to propperly ground the antenna for both operational and lightning protection.
Maybe this can clear up any confusion.


[Please login or register to view this link]

[Please login or register to view this link]

[Please login or register to view this link]

[Please login or register to view this link]

[Please login or register to view this link]

[Please login or register to view this link]

[Please login or register to view this link]

[Please login or register to view this link]

[Please login or register to view this link]


thanks!

[yamaha]

We are talking amateur radio standards. Commercial high voltage feed lines are a different story. What Daveman927 posted is how to ground a A99 not a 72500 volt Main line. His book(NFPA70) even has specific directions pertaining to AMATEUR RADIO. And he has posted this(appreciated).. Its The National Electrical code, there are many books and he has most of them. Anyways, If you get struck by lightning no matter what size ground you use your antenna/coax/transceiver are probably toast. I got my tower from a guy who lost everything due to lightning. I went and took the tower down after the strike. His a99 was vaporized! Coax burnt, melted and some of it just plain missing. And it was well grounded. The top section of the tower was even kinda twisted which Im not sure if that's from the strike or not. But If it was that's crazy. If mother nature Is upset she will destroy anything in her way.

[Savoirfaire]

Yes and lightning is very unusual.

It can jump.

I have heard of people having the coax unhooked and on the other side of the room or in another room and the lightning still jumps and gets the radio and other appliances, TV's, etc. in the house. I'd have never thought this but it happens even to Amateur Radio operators if not properly grounded. I have been fortunate over the years, especially during my early days until age 28 in CB radio.

What you do not know you do not know. I did not at that time although I did have 3 copper rods but I thought that was really a good ground. I know better now.

Read up on grounding as there are plans on the web that take the lightning far away from your station but always unhook the coax and get a good lightning arrestor and a way you can switch things open on the coax outside of your house preferably closer to the tower.

73, Frank

[MDYoungblood]

Lets just say the whole point of grounding an antenna is to keep the largest quantity energy outside, away from the living things inside and to minimize the damage to your property. Grounding is not going to save your equipment or damage from a direct strike but it does dissipates the static charges that happens naturally. If you think you are safe from any of these occurrences you should "Google" lightning strikes and check out some "YouTubes" on the subject. I have seen some personally and has changed my opinion about more is never to much.
[Please login or register to view this link]

3's

Greg

[barefoothank]

Based on an answer that "DB" gave in this thread [Please login or register to view this link] I opted to isolate my A99 from the mast so it would not be a "cloud warmer" but reading this thread makes me wonder if I did the right thing. I used a pole from an old electric chainsaw on a pole*.
[Please login or register to view this link]
My mast is grounded to a rod on one side of the house and my coax to another where it hooks up to my room.
I suppose I could run some ground wire up to the A99 and see if it still works okay, mostly this stuff is way over my head or I could say I'm out of my league.
*don't buy one they don't work well when extended as there is no leverage to cut and the saw just bounces off the limbs

[Stoneman]

I always welded a bolt on the bottom of the mast, then attached a car battery cable to the ground rod...

[The DB]

Based on an answer that "DB" gave in this thread [Please login or register to view this link] I opted to isolate my A99 from the mast so it would not be a "cloud warmer" but reading this thread makes me wonder if I did the right thing. I used a pole from an old electric chainsaw on a pole*.
[Please login or register to view this link]
My mast is grounded to a rod on one side of the house and my coax to another where it hooks up to my room.
I suppose I could run some ground wire up to the A99 and see if it still works okay, mostly this stuff is way over my head or I could say I'm out of my league.
*don't buy one they don't work well when extended as there is no leverage to cut and the saw just bounces off the limbs

That other thread was not about grounding, but performance and common mode currents. You did it right, your antenna is still grounded, it is just grounded differently than through the mast, which is fine. Some antennas require such methods to perform at their best.

The only thing I would recommend if you haven't done it yet is connect the two grounds together with a single wire (the heavier gauge the better up to about 4 AWG) to ensure they are always at the same potential. For DC and lightening, this will make the two appear to be the same, or very close to it, even if the tip of the mast is isolated from the antenna.


The DB