Need help on grounding an antenna

Pro RF · Post by **Pro RF** » Sun Mar 24, 2002 1:49 am

For the most part, I always had indoor antenna's. I have now moved a scanner antenna, dualband base antenna and a weatherstation windvane on a metal mast, mounted to the side of the house.

I have ran a ground wire from the top of the mast touching the two-way antenna mount, down the mast (zip tied), along the garage and under the deck. I still need to drive a ground rod into the dirt.

Am I missing anything? Will this actually ground the setup to help with lightning protection? We don't get many T-Storms here in CT, but when we do they can be intense.

Thanks!

Jonathan KC8RYW · Post by **Jonathan KC8RYW** » Sun Mar 24, 2002 2:25 am

First off, I'm wondering what gauge wire you are using for the ground wire. Is it copper, aluminum, or copper-clad?

Don't forget to tie in the antenna ground in with the electric box ground point. This is part of the National Electric Code. Plus, it actually makes sense.

If you can, it never hurts to put two or three grounding rods into the ground. Make sure that they are 8' or longer and copper. Aluminum grounding rods are better then nothing, but not the best.

That's all I can think of for now.

hfd376 · Post by **hfd376** » Sun Mar 24, 2002 2:59 am

Make sure you bond or connect to whereever the house electrical system is grounded. The reason for this is so that there wil not be multiple potentials for ground, one ground point being a "better" or lower resistance ground. Also, use a solid conductor copper wire of at least 12 guage.

Doug

Jim202 · Post by **Jim202** » Sun Mar 24, 2002 9:36 am

Grounding of antenna systems is important. Just remember that your trying to remove any charge that the antenna may have got in a strike. Your trying to get this charge to go into the ground in the most direct path.

Don't redirect it back into the house wiring by tying it to the electrical box ground. This is like asking for your house to catch on fire when the antenna takes a hit.

Yes the NEC says that you should tie the two ground systems together. This doesn't mean use the house wiring to do it.

The ground rods that you are intending to install, should all be tied together. They should be spaced at least double their length apart. This comes from the cone of influence of the earth around them. Any closer and your just waisting your money.

If at all possible, the ground rods should use exotheric welding to attach the ground wire to them. This will give you the lowest resistance and a non oxidizing connection. Use a #2 solid tinned wire to reduce the oxidation. It fits the common molds for the welding.

The ground wire should then be run around the outside of the house and connected to the electric meter ground. This then complies with the NEC to connect the 2 grounds together. The wire should be 18 inches or more below the surface. The depth is determined by the frost line in your area.

You will get as many answers as to the right way of grounding as the number of people you ask plus one. I have been in the two way radio field for over 35 years. Have been installing cellular sites for about 12 years. It never stops to amaze me as to the different ways I hear people say it has to be done.

Part of what you end up doing is based on just how much you can afford to invest in the grounding system. The more the better. Then on the other hand, there are those that do nothing. Just make shure the house insurance is paid up.

Jim

Pro RF · Post by **Pro RF** » Sun Mar 24, 2002 9:54 am

Thank Jim

Right now the antenna is mounted on the opposite side of the house then the electrical service (underground). I believe the wire is alumin...or whatever radio shack sells. The wire is "hooked" into a hole and the top antenna, and I don't believe it clears the roofline of the house, and is about 4-6 feet from the chimney of the house.

Now, should there be any concern about turns in the wire? What I mean is there is presently two 90 degree turns to get it from the garage roof down to the dirt.

Jim202 · Post by **Jim202** » Sun Mar 24, 2002 3:24 pm

Aluminum wire is not exactly the best down lead for grounding an antenna system.

One item that I forgot to mention and was reminded by the last post. Sharp bends in a ground wire are a no no. No bends less than an 8 inch radius. Lightning is like a speeding bullet. It doesn't like to make turns. The most direct, least turn path is the best.

Jim

jim · Post by **jim** » Mon Mar 25, 2002 2:13 pm

Don't tie it into the house wiring. Use the main ground. Forget about #12 wire- it will vaporize.

Jim202 hit it exactly right.

Nand · Post by **Nand** » Mon Mar 25, 2002 6:05 pm

Jonathan KC8RYW · Post by **Jonathan KC8RYW** » Mon Apr 01, 2002 9:58 am

April · Post by **April** » Mon Apr 01, 2002 2:37 pm

<IMG SRC="http://www.summit.net/home/af4cy/STORMYUJ.GIF" ALT="Lighting hitting antenna">

[/quote]
KC8RYW, How did you do this?
I like it, very approate.
April

RadioSouth · Post by **RadioSouth** » Mon Apr 01, 2002 2:39 pm

Didn't see any mention of grounding the lead in coax (polyphaser or similar). Very Necessary.

evanh · Post by **evanh** » Tue Apr 02, 2002 9:39 am

I would agree with the above comments. Just try to think about ALL of the possible paths that lightning might take in the event of a strike. Set up a detour to direct the strike around equipment and property and not through it.

Equalize the potential of multiple grounding electrodes by bonding them together with a heavy gauge copper wire.

Ground rods, power, telephone, cable-tv, satellite dish, and metallic water entrance pipes all contain a ground conductor of some sort in the service. The difference is that those different grounds vary in resistance or quality in relation to. and distance from each other. If your home and it's utilities were installed to modern codes, then the utilities should already be bonded together, or attached to the power ground.

Jonathan KC8RYW · Post by **Jonathan KC8RYW** » Tue Apr 02, 2002 9:57 am

On 2002-04-01 17:37, April wrote:
<IMG SRC="http://www.summit.net/home/af4cy/STORMYUJ.GIF" ALT="Lighting hitting antenna">

KC8RYW, How did you do this?
I like it, very approate.
April

I stole it from the AF4CY repeater page. (http://www.summit.net/home/af4cy/repeater.html)
While at that site, check out what they mounted their repeaters in... a big plastic box. Interesting.