Antenna grounding options

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graywoulf

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Greetings again,

I am looking at grounding options for my dipole antenna and I noticed that there is a grounding rod near the house power meter and main fuse box at the back of my house. There are other connections to this same rod that include the unused telephone junction box and the cable TV junction box as well. Would there be any problem with me attaching a 12 Ga copper wire that would then be attached to my home brew aluminum window pass through panel for the grounding of all of my antennas? Thanks.
 

mmckenna

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It won't cause an issue, that's what it is there for.

However, 12 gauge is kind of small for any sort of proper radio system grounding. The NEC says use 6 gauge.

And a single ground rod may not be enough, depending on local soil conductivity. If you need a good ground, you may need more than one rod. If you use more than one rod, they must all be bonded together.
 

prcguy

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If your going to connect the existing ground rod to something that grounds the shield of your antenna feedlines, NEC requires at least 10ga copper wire for that and there is a maximum distance you can run which is around 30ft then you must upsize the wire. If you install another ground rod NEC requires you bond that to the main house ground rod with no less than 6ga copper wire and there is a max distance on that but I forget. Look up NEC article 810 which deals specifically with grounding antennas.

Greetings again,

I am looking at grounding options for my dipole antenna and I noticed that there is a grounding rod near the house power meter and main fuse box at the back of my house. There are other connections to this same rod that include the unused telephone junction box and the cable TV junction box as well. Would there be any problem with me attaching a 12 Ga copper wire that would then be attached to my home brew aluminum window pass through panel for the grounding of all of my antennas? Thanks.
 

lmrtek

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You are always better to run a larger conductor than the NEC minimum requirement.
........
For best protection drive in a 8 foot rod below the window and run polyphaser copper grounding strap to it.
.......
Then connect a buried #6 bare copper bonding jumper to the entrance ground rod.
 

MUTNAV

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If your going to install another ground rod. You may want to make sure you aren't going to puncture a natural gas line or water line with it. Hey... this thing has spell check now!!!
 

mmckenna

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Is grounding to the incoming water line an acceptable option?

Not necessarily.
Water pipes can switch to PVC under ground. Usually in a large building, the water main gets grounded along with everything else.
If you know it's metal for quite a ways under ground, you could probably do it, but you'd really want to check with the national electric code about that.
 

graywoulf

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This house was built in 1940. The only PVC in the plumbing is the pipes in the basement that were replaced some time ago. Even the drain pipes are cast iron.
 

RFI-EMI-GUY

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The existing ground rod , if very old , or if simply a water pipe, can always benefit by a new 8 footer placed nearby and bonded to the existing.

Never disconnect the wire from your electrical service to the existing ground rod.

It is Ok to add a ground rod and clamps to bond a conductor to the original. You will probably be able to measure an AC voltage differential between the old and new before you bond them together.

If you need to bond an antenna ground wire some distance around the house, you can add ground rods every 16 feet using an 8 footer, and bond those all with #6 solid conductor.

Sent from my SM-T350 using Tapatalk
 

RFI-EMI-GUY

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Thank you very much sir! I will look into setting another ground rod that is closer to my radios.
That new ground rod MUST be bonded to your existing ground rod. The worst you can do is have two ground references in your home. It will guarantee damage will occur.

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ab3a

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Is grounding to the incoming water line an acceptable option?

Speaking as an engineer, retired from a 30 year career at a large water utility, no.

While it is likely that things will be okay, you don't know. In fact, many older homes used pipes made with lead alloys (under trade names such as TubeLoy). Any ground currents may cause electrolysis reactions to occur, possibly causing lead to increase in to your water supply.

I really can't recommend it.
 

jim202

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One of the points to elaborate on that EMI-RF-GUY mentioned is to space the 8 foot ground rod 16 feet away has to do with what is called the "cone of influence" around the ground rods. When you put a ground rod into the ground, the ground rod sets up an imaginary cone around it to obtain the least resistance. The diameter of the cone is equal to the length of the rod in the ground. So with an 8 foot rod, you get a cone that has a radius of 8 feet. Placing a second ground rod closer is just wasting your money. This is why the standard of spacing the ground rods twice their length apart gives you the max effect to obtain the lowest resistance.

Now let me bring up another very important issue. The normal ground rod is made of steel and is copper plated. Depending on how corrosive your soil is, will determine just how long a ground rod will be effective before the copper plating is ate away by the chemicals in the soil. My normal stand it to replace your electrical meter ground rod about every ten years or so. Just remember to kill the main breaker before you attempt to remove the ground wire from the meter box on the old ground rod.

Another thing that can happen in sandy or clay soil is that if you have any close lightning strikes, there is a possibility that the soil can glassify around the ground rod or to the ground rod. If this happens, you loose your low resistance ground. The ground rod will need to be replaced. Problem is you won't know this has happened without doing an earth ground measurement with the meter ground wire removed during the measurement. This will require using a special ground resistance meter to measure the earth resistance of the ground rod.

Hope this has provided some pointers and help in what your looking to do to ground your ham antennas.

Jim
 

graywoulf

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I had no idea that grounding could be so technical and involved. I have an electrician friend that I am going to consult in this matter. Thank you all for all of your information and advice.
 

atech

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Greetings again,

I am looking at grounding options for my dipole antenna and I noticed that there is a grounding rod near the house power meter and main fuse box at the back of my house. There are other connections to this same rod that include the unused telephone junction box and the cable TV junction box as well. Would there be any problem with me attaching a 12 Ga copper wire that would then be attached to my home brew aluminum window pass through panel for the grounding of all of my antennas? Thanks.
Grounding to a water pipe is NOT a good idea! Unless you like being zapped in the shower as its ALL connected! Use the ground rod and wire as stated!
 

RFI-EMI-GUY

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I don’t know if electrical grounding and RF grounding are 100% the same?

They can be if the bonding inductance is low enough. That said, usually it is not (Mid-HF and up) and you still need a counterpoise on your antenna. The electrical grounding primarily makes sure that if there is a lightning strike nearby, that the energy dissipated in all of your equipment goes to one single point ground.

I don't know if a typical electrician cares/knows * more than grounding an electrical panel.

An COMPETENT installer of Dish TV antennas, likely/should have been trained on how to ground to existing residential service. I had DISH, and they installed a new rod at the point just below my DISHes and ran a conductor to bond my existing service, The CATV folks bonded properly as well, though their work was shoddy and I had to put it all in a box and clean it up.

* Maybe I am still miffed about fixing shoddy and dangerous wiring in my last two homes. Backstabbing outlets, though it meets code, is an awful practice and causes IR drop under high continuous loads. Use the brass screws dummy!
 
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