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Author Topic: Ground Rod Length  (Read 13367 times)
KC0KEK
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« on: November 15, 2011, 06:37:52 AM »

Is there an ideal length for the rod used as a lightning ground? At the local Menards, I've got two choices: a pinkie-thick ground rod about 4 feet long that's designed for TV antennas, or a 10 footer with heavy copper cladding that's as big around as my thumb. Does the longer length make for a better ground simply because there's more contact with the soil? The 10 footer is only about $11, so my only concern is being able to drive it into the ground.

If it matters, I live in an area with a lot of clay -- so much so that if I had a kiln, I could fire pots morning, noon and night. Does clay affect ground conductivity to the point that a longer ground rod should be used?

Thanks in advance.
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NA4IT
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« Reply #1 on: November 15, 2011, 06:55:53 AM »

1) Do some reading on station grounding. Lots of info on the internet, Google is your friend.
2) Go with the 10 foot.
3) A fence post driver works well for getting the rod in the ground to about 3 feet. Then it's sledge hammer. Or you could try a hammer drill chucked on top of the rod.
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K2OWK
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« Reply #2 on: November 15, 2011, 02:07:09 PM »

Just to let you know, there is a slide hammer that is made for putting in grounding rods (the 8' to 10' types). Check with the local power company to see where you can obtain one. I do not think they are very expensive.

Hope this helps with the clay problem.

73s

K2OWK
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K9KJM
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« Reply #3 on: November 15, 2011, 09:24:57 PM »

A big problem with most all of the short skinny ground rods on the market is that they are NOT heavy copper clad, But only copper plated with a very thin plating that rusts out in short order.

(All of the local Menards stores in this area sell 8 foot long rods, Both 1/2 and 5/8" diameter, In the 10 to 11 dollar range each.  They are UL approved, With nice thick copper cladding.  I expect if there is a difference in lengths it may be due to local electrical codes?) 

So the answer is as already stated, Go with the longer rod.  If you cannot borrow a driver, The fence post drivers are only about 19 bucks at Menards, Or a short length of steel pipe with a pipe cap on one end can be used in  a pinch to get the rod about half way so you can reach it with a big hammer.
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KC0KEK
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« Reply #4 on: November 16, 2011, 06:28:30 AM »

All of the local Menards stores in this area sell 8 foot long rods, Both 1/2 and 5/8" diameter, In the 10 to 11 dollar range each.  They are UL approved, With nice thick copper cladding.  I expect if there is a difference in lengths it may be due to local electrical codes?

Thanks. The sales guy kept telling me that the big rods are for grounding an entire house's electrical system rather than antennas. Okay, maybe if all you're worried about is a TV. The thick copper cladding alone was enough to make me lean toward them, despite what he said.

BTW, this sales guy also said hams come in all the time asking about ground rods. I was glad to hear that some of them invited him to visit the ARRL website to learn more about the hobby.
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K9KJM
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« Reply #5 on: November 16, 2011, 09:00:44 PM »

[quote author=
Thanks. The sales guy kept telling me that the big rods are for grounding an entire house's electrical system rather than antennas. Okay, maybe if all you're worried about is a TV. The thick copper cladding alone was enough to make me lean toward them, despite what he said.

BTW, this sales guy also said hams come in all the time asking about ground rods. I was glad to hear that some of them invited him to visit the ARRL website to learn more about the hobby.
[/quote]

Sounds like the "Sales guy" knows about zero or perhaps even less about lightning protection........
Even worse than zero knowledge about a subjet is misinformation......  And then spreading that misinformation on to others.
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AD4U
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« Reply #6 on: November 17, 2011, 05:41:48 AM »

An effective ground requires a number of things.  Two very important "things" are:

1.  The surface area of the ground rod that is in contact with undisturbed earth

2.  The soil conditions in your area

You cannot do much about #2 (Epson salts helps) but you definitely have a lot of control over #1.  Buy the heavy plated 10 foot ground rod.  Drive it into the ground all the way.  Then connect it to the ground rod where the AC power enters your house.

Google "Polyphaser" or go to the W8JI site for al the grounding info you can possibly want.

Dick  AD4U
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WX7G
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« Reply #7 on: November 17, 2011, 08:52:44 AM »

The larger rod is definitely better for lightning protection.

If you want maximum protection use the ground rod (or not) and route the antenna cables to the AC Service entrance ground. From there route the cables to the shack. The house AC wiring now out of the path of lightning charge.
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KC0KEK
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« Reply #8 on: November 17, 2011, 04:25:10 PM »

If you want maximum protection use the ground rod (or not) and route the antenna cables to the AC Service entrance ground. From there route the cables to the shack. The house AC wiring now out of the path of lightning charge.

Thanks. As luck would have it, the house ground is just outside the window from my new operating position.
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W6RMK
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« Reply #9 on: November 17, 2011, 09:34:40 PM »

the 4 foot rod isn't legal or useful for grounding of anything.  Maybe you could use it keep a tent from blowing away. Might make a nice stake to hold up the bushes around the antenna lead in.
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NJ3U
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« Reply #10 on: November 18, 2011, 06:21:05 AM »

Let me preface this post by saying I not an expert on this, however a couple of observations I've made;

Lightning wants to go to ground as easily and quickly as possible.  It doesn't want to fry your gear, it just wants to go to ground.

It's better to show ground an easy path to ground outside of your house then route it through and back out.

The better ground you provide the less chance of having it come inside.

More ground rods are better than less.  (So buy the bigger, thicker, copper clad rods)

All grounds should be connected so the energy doesn't run into a dead end route and jump to some unplanned object (your nice HF rig)

Most damage comes in through the power lines and/or phone lines - So unplug your gear when not in use as added insurance

Antennas do not attract lightning any more than most other things in your vicinity (trees, water towers...)

Companies spend a lot of money protecting their facilities / assets from lightning, so plenty has been written on the topic. 
Do your homework and ask an Elmer for assistance.
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N7TEE
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« Reply #11 on: November 18, 2011, 02:18:03 PM »

One of the easiest ways to drive a ground rod is to dig a shallow hole about three inches in diameter and about two inches deep.  Fill it with water and useing your hands drive the rod a few inches into the ground thru the water and when it gets stuck twist and pull then add more water, until it is within a foot or two of the ground.  Then use a sledge hammer to drive it the rest of the way.  Works great and less tiring than a post driver.
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K9KJM
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« Reply #12 on: November 18, 2011, 10:28:37 PM »

Beware of the "water" method of driving ground rods.   While some moisture added to the area can help get ground rods in with no ill effect, You DO want real firm contact with the soil to the rod.  So "working" a rod up and down while washing with water is not a good thing to do.  Much worse is the method promoted by some of using a copper tube and "washing" it in......   That is a method to avoid.
The best, Easiest way is to rent or borrow some type of "jackhammer" that can power drive them in.

For tips on lightning protection on a budget:
 http://www.scribd.com/doc/14868226/lightning-protectiontaming-thors-thunderon-a-budget

(Give that site plenty of time to load)
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NN4RH
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« Reply #13 on: November 19, 2011, 05:34:17 AM »

1) Do some reading on station grounding. Lots of info on the internet, Google is your friend.

Sure. And the vast majority of what you find on the internet about "station grounding" is utter nonsense, and a good portion of it is dangerous.


Best grounding advice is to listen to w8ji or k9kjm, and ignore everyone else.
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KC0KEK
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Posts: 127




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« Reply #14 on: November 19, 2011, 08:10:25 AM »

1) Do some reading on station grounding. Lots of info on the internet, Google is your friend.

Sure. And the vast majority of what you find on the internet about "station grounding" is utter nonsense, and a good portion of it is dangerous.

Exactly why I posted here: to do a reality check on what I've read elsewhere, including the ARRL Antenna Book.
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