I am installing a ham radio and want to properly ground it

Question

I am installing a ham radio and want to properly ground it.

I will be including a lightning arrester that will also go the the ground.

I will have a 20' mast with a long wire antenna running 130+ feet out to the south. The far end will be about 45 feet above ground level.

There is a ground connection on my mounting plate and also on the plate in my window that feeds the transmission lines in and out of the house. Inside I will have a 3 to 4 foot piece of copper pipe which will be common to all the cases of my system. It will be tied to the window ground feed through and from there to the ground rod.

I live in the North Western Arizona Desert and the ground is very dry. I am installing an 8 foot ground rod and because of the caliche I'm having to actually drill thru the dirt to put the rod in.

• Would I benefit from multiple rods along the side of my house? Would copper pipe work as well, or better than, the steel rod which is copper clad?

• Would it benefit my ground to run a slow drip maybe a gallon a day into the copper pipe so that the dirt at the bottom remains wet?

• The pipe sections are 10' long vice the 8' of the rods. Will that help a lot or a little?

• What else should I do?

• What gauge wire should I use and should it be stranded, like the ground straps in a car, or solid or both?

Answer 1

The W8JI information is pretty good, there are a few points he doesn't touch on though.

"EARTHING" or Grounding is a hot subject in many areas and there are many theories related to it.

The NEC and NFPA recommend that ALL "Extra" grounds attach back to the electrical service ground ( I suggest you read up on this).

Arizona presents its own problems to the grounding question. I suggest you contact your county surveyor, he may be able to tell you how deep the water table is in your area or put you in contact with the state or Federal "Hydrologist" who should be able to provide the information (get a rod down into the water table if possible).

Any connections you make should be made with an Anti-oxidant Grease (such as "No-LOX") especially if connecting dissimilar metals and use as large a wire as possible.

If you live in a lightning-prone area, make provision for "QUICKLY" disconnecting your station equipment from the antennas and if you're going to be absent from the station for some time DISCONNECT !

This subject can get pretty involved - Google can be your friend here.

Answer 2

Where I live in Michigan, the soil is always moist a few feet down. Also, the ground system must be below the frost line, which is 46" here. Thus, pounding a long rod into the soil is a natural solution, and it's easy enough with nothing more than a 5 lb engineer's hammer.

I'm hardly an expert in grounding in dry areas, but certainly your situation is much different. Eight feet may not be deep enough to get into moist soil. And frost is hardly a concern. And digging that deep is not easy.

A water drip on the grounding rod may help, if you can maintain it. Ideally you want enough to maintain moist soil, but not so much that all the salts in the soil are washed away. Even wet, your soil may not have great conductivity, so you'll still need to do more if you require a very good ground.

An effective ground doesn't necessarily need to go deep: it can also go out. Several ground rods, about as far apart as they are deep, connected with 6 AWG solid wire or even better 0.022" solid copper strap will lower the ground impedance by spreading over a larger area. I suspect in Arizona you'd need quite a lot of ground rods to get a good ground.

I'd bet most buildings in Arizona use an Ufer ground, which basically just means grounding to the rebar in the foundation. Since the Ufer ground likely extends through the entire foundation, its possible there's a place the rebar has been exposed and you can connect to that. It's almost certainly exposed at your electrical service entrance, but if that's not also where the feedline enters the house you have a bit of a problem.

Other solutions are variations on the Ufer ground, which involve digging a trench or a grid of many trenches about 30" deep, then laying an electrode in them surrounded by some kind of ground enhancement material. Bentonite clay is cheap, though there are engineered solutions which work better.

I couldn't tell you how big this ground system needs to be. Do you need to withstand multiple direct, large strikes? Or can you settle for a lesser degree of protection? One thing you can do is see what builders are doing, since the national electric code specifies a minimum performance for grounding, then use that as a baseline.

Answer 3

The information I have recently read indicates a very complex solution, perhaps because it is not always easy to get a good/proper solution, especially in your situation.

I am originally from Arizona too, so I am aware of the unique problems there.

This solution worked for DC ground, AC safety, lightning protection, and RF:

The general idea is that for maximum effect you will need multiple ground rods spaced 8-10 feet apart and all connected by a large diameter wire (#6 or larger).

Do not use stranded wire or braid if possible due to the fact that at RF the wires work individually instead as a single conductor and they can also be broken easier.

The illustration I saw had 8 or more rods going around the house from the main electrical box connected to more rods at the tower, and close to the operating position.

The article also stated that it was important to tie the main electrical box ground to the tower and the equipment location (often not very near each other) in this manner.

There were more excellent ideas and explanations in the article. I will try to find it on my computer and link to it later.

There is also the problem of the poor connection of each rod to the earth. This can be helped considerably with any of the following:

1. bentonite surrounding the rods (not the lowest resistance, but much better than what you have, also needs to be kept moist to be effective, is the main ingredient in most pet litters).

2. rods with chemical salts that leach into the soil but may not be effective in your soil that is dry and hard (can be expensive, dissipates into the soil, so you need to buy more salts every so often and may also be a pollutant in the soil, especially if you have a well for drinking water).

3. carbon based material (somewhat effective but also dissipates into the soil, but may not be effective in your soil that is dry and hard).

4. proprietary material (can be expensive and is usually something like an enhanced clay similar to bentonite mixed with other things like carbon, but often no need to keep it moist)

5. conductive cement (excellent with the lowest resistance of all these solutions, but the cost will be a little expensive)

I recommend conductive cement if possible. It is a little more expensive, but it is a permanent solution and not difficult to use and does not pollute anything. You can find it if you search for it on the internet.

I checked my files and the information I read was indeed at the W8JI website and I found even more information than what I read.

Answer 4

This Might be Helpful !

https://sites.auburn.edu/admin/facilities/spw-bid-calendar/11-150%20AU%20Regional%20Airport-Construct%20a%20Self-Supporting%20Radio%20Tower/Project%20Documents/1/Motorola_R56_2005_manual.pdf

Motorola has done quite a bit of research on this subject. Good luck.