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What exactly does it mean to ground a Antenna?

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MichaelxB

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The title says it all. What exactly does grounding a antenna mean? And how do you ground a antenna? I'm a amateur when it comes to antennas so I'd appreciate if someone could explain all this to me. I'm a shortwave listener and am looking to move on to a bigger antenna so these are my questions. Thank you!

1. What does it mean to ground a antenna? (Like what is the point of grounding a antenna)
2. How do you ground a antenna? (What is the step by step process of grounding a antenna)

If you could, please explain these simply. I'm not a professional on this like the rest of you on here :)
Or link videos, how-to's or anything else that will help!
 

dmg1969

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Newport, PA
The title says it all. What exactly does grounding a antenna mean? And how do you ground a antenna? I'm a amateur when it comes to antennas so I'd appreciate if someone could explain all this to me. I'm a shortwave listener and am looking to move on to a bigger antenna so these are my questions. Thank you!

1. What does it mean to ground a antenna? (Like what is the point of grounding a antenna)
2. How do you ground a antenna? (What is the step by step process of grounding a antenna)

If you could, please explain these simply. I'm not a professional on this like the rest of you on here :)
Or link videos, how-to's or anything else that will help!
The whole grounding issue is why I have not, to date, put up an external antenna. I make due with an attic mounted antenna. My basic understanding is that the metal mast should be grounded to earth. The coax feeding off of the antenna should be grounded to a ground block, which is also grounded to earth. That being said, there are others who say that electrical code dictates that the grounding wire be tied into the house's electical panel ground. That seems counter-intuitive to me...you keep the surge out of your home by bringing it into your home?
 

SCPD

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If you have the time, call the city or town electrical inspector, you want to make sure you comply to the regulations they require on grounding.
 

Flatliner

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There are several reasons for grounding. Firstly, remember that you're using an electrical circuit. You can't make current flow unless the circuit is complete. In our case, we're connecting one part of the circuit to the air, and the other to the earth. Otherwise the current will have no "reason" to travel through the cable and through the radio, as it needs a potential difference. In practice, earthing can be supplied by leakages and just the inefficiencies of the radio, and, of course, the power supply charges the circuit. Simply the process of the radio warming slightly while is use, is providing the potential difference needed to allow current to flow. Of course converting ordered energy into disordered energy, heat, is simply adding to the cooling of the universe. Your part in increasing entropy, will eventually kill all life in the universe. So, is listening to Raj of Station Taxis inability to program his satnav really worth it??!!!!

Ahem...

Another reason to ground, is to remove unwanted transients from the equipment.
 
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Flatliner

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I forgot to reply to your second question. Earthing is ideally done by connecting a wire from each device to a copper stake, driven into the ground.
 

902

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It's important to ground or "earth" (as our UK friends say) an antenna because of two things:

1 - it may fall and through some unforeseen circumstance, may come into contact with a power line or energized object, like a metal fence with a power line across it somewhere else, and

2 - it may get hit by lightning.

In either case, with a good earth ground, the energy would go directly from the antenna into the ground rod. If you don't have one, it will go through your radio, your house, and very possibly you. All bad in varying degrees. Radios can (and do) smoke. Your house can catch fire. You can be a part of that energy looking for the most direct path to ground... and if it follows the right path through your body, it can stop your heart's impulses that cause it to beat - or, if there's enough current/voltage (we're using Ohm's Law), can even cause you to burn.

Much of that can be prevented by being safe, careful, and aware when you put up your antenna, and also installing a ground rod and an appropriate diameter conductor (wire) going from your antenna directly to the ground rod.

That still doesn't mean that you shouldn't disconnect the antenna when you're not using the radio, and it still doesn't mean that you shouldn't use a lightning suppressor, like a Polyphaser or similar device on your transmission line.

And, various codes and uses (now we're getting into licensed electrician territory) may require grounds be tied together. If you have any doubt, do check with a licensed electrician. A little bit of prevention may save your, or your family's life.

You can read up on this stuff here: Article 810 - Radio and Television Equipment

And here: http://www.reeve.com/Documents/Articles Papers/AntennaSystemGroundingRequirements_Reeve.pdf
 

WA0CBW

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There are several things involved in "grounding" an antenna and they relate to the National Electrical Code (NEC). One item is grounding the mast that supports the antenna. The other is that the shield of the coax must be grounded before it enters the building. This includes TV, satellite, cable, and any other coax cable that enters the building. In addition the NEC requires that ALL grounds be connected to the main service panel electrical ground. This is the principle of "single-point-grounding". Most lightning damage occurs from flash-over. An electrical surge is looking for a difference of potential so if you have a ground rod on the opposite end of your house from the main electrical ground they will have a potential difference and there will be a flash over between the two different grounds. Hence the requirement for ALL grounds to be connected together. In addition it is good practice to connect the ground lug of your equipment to this same single point ground. Installing a coax line surge suppressor on each coax is also recommended. This suppressor should also be connected to the single point ground. To be fully protected you should also install an AC line surge arestor. Check out the NEC code sections 800, 810, and 820 for the specifics of wire size, distance from other conductors and other NEC installation requirements.
BB
 

Flatliner

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To summerise.

You'll set fire to your house, and yourself.
You'll kill all other life.
The universe will die.

Enjoy!! :D
 

majoco

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Good question and the usual crop of answers.
I'll ask a question too. How many instances have you seen of a "professional" installation of a domestic TV antenna system and was there a ground stake? You would have thought that a "Professional" would have adhered to the local electrical bonding codes to the absolute letter of the law. But no, the antenna goes to the TV with no ground in the system, sometimes not even grounded through the TV with a 12volt or other supply. Are you saying that all these installations are illegal? I defy anyone to go to city hall and ask the electrical inspector to condemn every TV antenna installation and fine every TV installer..

In the seven houses that I have lived in in the last forty years and have erected antennas for all sorts of SWL, scanning and ham use, I have buried a ground stake outside the room or shed where the radios were installed. Radios, coaxes and antennas were grounded to this stake which was not connected to the electrical panel ground stake. I have endeavoured to keep the antenna currents and the electrical currents entirely separate to avoid house interference appearing in the antenna circuits of the radios and it's worked well. I have never been struck by lightning, despite some nearby strikes and never had any damage to any of my rigs due to static discharge.

To answer the OP's question, ground the mast or metalwork that you mount the antenna on and maybe ground the outer of the coax cable where it enters your house or whatever. Don't ground any 'active' part of the antenna - that would render it very noise-free!
 

majoco

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Electrical supply stores have bronze ground clips that clamp on to the stake with a large threaded stud where you connect your cables. Or else just trap the wires under a hose clip if you're cheap like me!

Another thing to notice is that Flatliner is in the UK and I am in New Zealand - local electrical wiring regulations are going to be different. Fortunately NZ is not a 'Nanny' state where legislation is there to protect people from their own stupidity. You can do whatever you like as long as you don't put other people in danger.
 

MichaelxB

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Electrical supply stores have bronze ground clips that clamp on to the stake with a large threaded stud where you connect your cables. Or else just trap the wires under a hose clip if you're cheap like me!

Another thing to notice is that Flatliner is in the UK and I am in New Zealand - local electrical wiring regulations are going to be different. Fortunately NZ is not a 'Nanny' state where legislation is there to protect people from their own stupidity. You can do whatever you like as long as you don't put other people in danger.
Thanks. And luckily I live in a rural area in the U.S. and have no neighbors nearby at all. So no one will be in danger here my friend. :D
 

RC286

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There are many aspects, differences and reasons for grounding.

I will start off with reasons why you should or might need to ground an antenna.
-your antenna requires an RF ground to function correctly.
The antenna may not have a ground plane or counterpoise to effectively match the antenna. A counterpoise can be a wire or radials usually 1/4 wavelength or longer than the frequency of intended operation. Some ground planes will work independently of a physical ground. It is still technically an RF ground, just not earth grounded. For example my CLR-2 5/8 wave cb antenna will work happily regardless of whether I have it earth grounded or not. Some ground planes or RF grounds employ ground rods berried at the base of a tower or antenna mast using the earth as an RF ground counterpoise for the antenna to work against. Some installations use radials stretching outwards from the base of a tower or mast like spokes on a wheel. This creates a ground plane for the antenna to work against, the more radials the higher the efficiency. Some antennas using matching transformers, such as baluns or ununs require a ground to function properly. A common scenario is a wire dipole. It can be fed with 450 ohm twin lead, or open wire, and work efficiently when connected to a suitable transmitter, however this means the feed line also radiates as part of the antenna bringing RF into the shack. Perhaps you want to connect a dipole such as a G5RV to a transmitter with a 50ohm unbalanced output fed with coaxial cable, the antenna will use ladder line or twin lead to connect to a balun (balanced to un-ballanced) transformer. If the balun is not grounded, the coax will radiate RF on its shield. Some long RF grounds might require being impedance matched, there is a simple solution using a chunk of coax as a grounding conductor to bleed off RF to ground that the standard copper wire may not be able to do. RF acts very differently than DC or low frequency AC on conductors, and sometimes what seems a good DC ground may choke RF and not allow it to flow to ground.

-lightning protection and safety ground.
Lighting protection is one of the main reasons to ground an antenna if the antenna does not require a ground to function properly. Such grounding will help protect your system from near strikes, but if you take a direct hit, you will usually suffer some damage. The amount of damage depends on the grounding system. Most hobbyists cannot afford a grounding system capable of dissipating a direct hit with lightning such as the systems employed by commercial broadcast antennas. These grounding systems cost thousands of dollars and are usually out of the budget for most of us. Spend as much as you can afford on your grounding, largest conductors you can afford etc. Lighting grounds must also be as short and straight as possible, smooth (such as solid copper or copper pipe, avoid braided or twisted conductors if possible, though 99% of the time that is all that is available, anything is better than nothing) So you've grounded your antennas with ground rods, now is a good idea for a safety grounding bond. This may not only be required by local codes, but is a good idea. This is a bonding conductor that connects between the electrical service ground and your antenna grounds, bringing them to the same voltage potential. My grounding system was installed a bit at a time due to finances. At one point my antennas were grounded from their feed points outdoors, but not bonded to the electrical service ground. I found out first hand what the purpose is for having a safety bond. I was adjusting my SX-99 receiver, which has a grounded power cable installed, thus grounded to my electrical service, I reached over with my other hand to power up another receiver that only has a 2 prong plug, so its ground was provided by the antenna coax to the antenna ground rods. I received an unexpected jolt. Not enough to be lethal, but enough to surprise me. Both grounds were near 30v different potential.

-Entrance grounding and equipment grounding,
If you have alot of interconnected equipment like myself and others, you may want to employ an equipment ground. This is a ground line run into the shack feeding a bus which you ground all of your equipment to. This reduces RF on the equipment, noise, and keeps the chassis all at the same potential to prevent more extreme damage should you take a lightning strike and have the discharge enter the shack. This is not a fail safe ground, but it will reduce the chance of the discharge entering one radio and traveling through it and possibly many others looking for its way to ground. Ground all of your equipment to a common point to reduce the possibility of ground loops, which can be a nuisance and a pain to diagnose if you have a handful of interconnected equipment.
Entrance grounding is the final stand at keeping lightning from getting into you shack/house. It usually employs grounded couplers or lightning restorers (more appropriately called static arresters as lightning will surely destroy them and get through) mounted on a large ground bus and bonded to your EXTERIOR grounding conductors. This is usually installed just before the feedlines enter the building.

My current grounding system that has been a work in progress for a few years consists of 4 ground rods grounding my antennas at their feed points either via the metal brackets bonded to the coax connections, or to the appropriate ground terminals on the balun/ununs. The rods are all bonded with #3 awg copper wire, and the antenna ground system is bonded to the electrical service ground with #3 copper. A length of #3 copper runs into the shack connecting to a master bus for my equipment ground consisting of a heavy bus with many lugs attached. from there smaller conductors ground ALL of my radios and equipment, even the audio processing, PCs, and backup power supplies using provided ground terminals, and if not available to a screw that makes good electrical contact with the chassis. A #4 braided conductor goes from the main bus to a second bus where my antenna switches and low pass filter are mounted providing additional grounding. I did notice that when the equipment ground was installed along with the safety bond, my noise floor dropped 2 S units. So at the very least I made it easier to receive signals.

To sum it up, yes ground, spend as much as you can afford, and don't be afraid to add on to the system to make it more reliable later on. Will it save your equipment from a direct lightning strike? Probably not, but it will increase the survival chances. Make sure your grounding complies with local codes, and your insurance covers lighting damage, that way if something is to happen, you will be covered.

all in all, any ground it better than no ground.
 

MichaelxB

Member
Joined
Mar 7, 2014
Messages
30
Location
Illinois, USA
There are many aspects, differences and reasons for grounding.

I will start off with reasons why you should or might need to ground an antenna.
-your antenna requires an RF ground to function correctly.
The antenna may not have a ground plane or counterpoise to effectively match the antenna. A counterpoise can be a wire or radials usually 1/4 wavelength or longer than the frequency of intended operation. Some ground planes will work independently of a physical ground. It is still technically an RF ground, just not earth grounded. For example my CLR-2 5/8 wave cb antenna will work happily regardless of whether I have it earth grounded or not. Some ground planes or RF grounds employ ground rods berried at the base of a tower or antenna mast using the earth as an RF ground counterpoise for the antenna to work against. Some installations use radials stretching outwards from the base of a tower or mast like spokes on a wheel. This creates a ground plane for the antenna to work against, the more radials the higher the efficiency. Some antennas using matching transformers, such as baluns or ununs require a ground to function properly. A common scenario is a wire dipole. It can be fed with 450 ohm twin lead, or open wire, and work efficiently when connected to a suitable transmitter, however this means the feed line also radiates as part of the antenna bringing RF into the shack. Perhaps you want to connect a dipole such as a G5RV to a transmitter with a 50ohm unbalanced output fed with coaxial cable, the antenna will use ladder line or twin lead to connect to a balun (balanced to un-ballanced) transformer. If the balun is not grounded, the coax will radiate RF on its shield. Some long RF grounds might require being impedance matched, there is a simple solution using a chunk of coax as a grounding conductor to bleed off RF to ground that the standard copper wire may not be able to do. RF acts very differently than DC or low frequency AC on conductors, and sometimes what seems a good DC ground may choke RF and not allow it to flow to ground.

-lightning protection and safety ground.
Lighting protection is one of the main reasons to ground an antenna if the antenna does not require a ground to function properly. Such grounding will help protect your system from near strikes, but if you take a direct hit, you will usually suffer some damage. The amount of damage depends on the grounding system. Most hobbyists cannot afford a grounding system capable of dissipating a direct hit with lightning such as the systems employed by commercial broadcast antennas. These grounding systems cost thousands of dollars and are usually out of the budget for most of us. Spend as much as you can afford on your grounding, largest conductors you can afford etc. Lighting grounds must also be as short and straight as possible, smooth (such as solid copper or copper pipe, avoid braided or twisted conductors if possible, though 99% of the time that is all that is available, anything is better than nothing) So you've grounded your antennas with ground rods, now is a good idea for a safety grounding bond. This may not only be required by local codes, but is a good idea. This is a bonding conductor that connects between the electrical service ground and your antenna grounds, bringing them to the same voltage potential. My grounding system was installed a bit at a time due to finances. At one point my antennas were grounded from their feed points outdoors, but not bonded to the electrical service ground. I found out first hand what the purpose is for having a safety bond. I was adjusting my SX-99 receiver, which has a grounded power cable installed, thus grounded to my electrical service, I reached over with my other hand to power up another receiver that only has a 2 prong plug, so its ground was provided by the antenna coax to the antenna ground rods. I received an unexpected jolt. Not enough to be lethal, but enough to surprise me. Both grounds were near 30v different potential.

-Entrance grounding and equipment grounding,
If you have alot of interconnected equipment like myself and others, you may want to employ an equipment ground. This is a ground line run into the shack feeding a bus which you ground all of your equipment to. This reduces RF on the equipment, noise, and keeps the chassis all at the same potential to prevent more extreme damage should you take a lightning strike and have the discharge enter the shack. This is not a fail safe ground, but it will reduce the chance of the discharge entering one radio and traveling through it and possibly many others looking for its way to ground. Ground all of your equipment to a common point to reduce the possibility of ground loops, which can be a nuisance and a pain to diagnose if you have a handful of interconnected equipment.
Entrance grounding is the final stand at keeping lightning from getting into you shack/house. It usually employs grounded couplers or lightning restorers (more appropriately called static arresters as lightning will surely destroy them and get through) mounted on a large ground bus and bonded to your EXTERIOR grounding conductors. This is usually installed just before the feedlines enter the building.

My current grounding system that has been a work in progress for a few years consists of 4 ground rods grounding my antennas at their feed points either via the metal brackets bonded to the coax connections, or to the appropriate ground terminals on the balun/ununs. The rods are all bonded with #3 awg copper wire, and the antenna ground system is bonded to the electrical service ground with #3 copper. A length of #3 copper runs into the shack connecting to a master bus for my equipment ground consisting of a heavy bus with many lugs attached. from there smaller conductors ground ALL of my radios and equipment, even the audio processing, PCs, and backup power supplies using provided ground terminals, and if not available to a screw that makes good electrical contact with the chassis. A #4 braided conductor goes from the main bus to a second bus where my antenna switches and low pass filter are mounted providing additional grounding. I did notice that when the equipment ground was installed along with the safety bond, my noise floor dropped 2 S units. So at the very least I made it easier to receive signals.

To sum it up, yes ground, spend as much as you can afford, and don't be afraid to add on to the system to make it more reliable later on. Will it save your equipment from a direct lightning strike? Probably not, but it will increase the survival chances. Make sure your grounding complies with local codes, and your insurance covers lighting damage, that way if something is to happen, you will be covered.

all in all, any ground it better than no ground.

Wow, thanks for taking the time to explain it to me in good detail. Very helpful, appreciate it! :D
 

hitechRadio

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Messages
392
A lot of good advise posted.

Different antennas may require different types of grounding installations.

Is the antenna mounted on something conductive. A Tower is conductive a wooden pole is not, a tripod mount on a roof is conductive but the structure (roof) it is mounted on is not.

On a tower you ground the tower at the base, no need to run a separate ground wire all the way to the top to the antenna, waist of money and time.

On a roof or a telephone pole you would need to run a separate ground to the antenna. In the case of a wooden pole, running a ground to the metal bracket that supports the antenna would suffice. A tripod mount on a roof grounding to the tripod should suffice.

It is always good practice to ground the shield of the coax near the antenna and depending on height of your structure every 100feet.
Then you would ground the coax shield just BEFORE you make the horizontal transition to the comm room.

Then just before you coax enters your house you would install a lightning arrestor, like a polyphaser, do not skimp here. You must have a good quality arrestor. The arrestor must be grounded to a ground rod that is grounded and that ground rod must be grounded back to the structure.

Building codes may dictate, you should also ground your AC and any other ground rods around your house such as cable tx, satellite, telephone, etc. to the antenna structure ground. Most new houses will have all of these grounds located at the AC ground rod.

You will also need to ground all your radios to this main ground.

Besides safety, if you want your equipment to survive a lightning storm. All equipment Must rise and fall in voltage at the same time. What happens when you have differenced in voltage? you have current flow. Current flow is what damages, lets the smoke out some would say of electronics.

Example, lets say you do not ground you house AC to and tower grounds together. The COAX Shield (Ground) and the ground plug in your wall would have a different voltage potential. Thus current will flow, and damage occurs.

One ham I met cut the ground off all his power supply's, his thought was since his tower and AC ground were not connected he would eliminate the difference in potential. Because his stuff kept getting blown up and the lightning was coming in through the ground. I reminded him that neutral is connected to ground. Long story short his equipment had the smoke let out again, installed a ground wire between AC ground rod and tower and entry ground rod. So far, no more smoke.

Commercial equipment at tower sites take lighting strikes all the time, and if designed correctly will survive years and years of lighting strikes with no damage. The equipment in the building may rise in voltage possibly thousands of volts, but as long as that voltage of each and every piece of equipment and metal object in that building rises and falls at the same time. There will be nearly no current flow. Thus no damage. Most of the high voltage will be shed by the tower and entry port, any voltage that gets in you need to control it. Because you cannot stop it.

Also remember you do not have to take a direct strike, to cause damage.
 
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MichaelxB

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Is the antenna mounted on something conductive. A Tower is conductive a wooden pole is not, a tripod mount on a roof is conductive but the structure (roof) it is mounted on is not.

On a tower you ground the tower at the base, no need to run a separate ground wire all the way to the top to the antenna, waist of money and time.
I have not yet got a new antenna, as I have not upgraded my receiver to a better unit yet. But, most likely the wire will be run up a old tall cable TV antenna, which has been stuck in the ground for years, and is very large. So how would I go about grounding it? Because I cannot move it.
 

hitechRadio

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Messages
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I have not yet got a new antenna, as I have not upgraded my receiver to a better unit yet. But, most likely the wire will be run up a old tall cable TV antenna, which has been stuck in the ground for years, and is very large. So how would I go about grounding it? Because I cannot move it.
If the mast/pole is metal, clean of any paint or rust and you could use a pipe clamp or drill a hole through it and solder a ring lug on ground wire. Install a ground rod near the base of the pole. and ground the other end of the conductor to the ground rod. If your AC ground rod is near by I would bury a bare copper conductor to connect to that ground rod also.

This being said every installation can be slightly different, provide use some pictures of the mast maybe and rough distance of other ground rods.
Other guys here may have some good ideas too.

Is this a scanner your installing?
 

MichaelxB

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If the mast/pole is metal, clean of any paint or rust and you could use a pipe clamp or drill a hole through it and solder a ring lug on ground wire. Install a ground rod near the base of the pole. and ground the other end of the conductor to the ground rod. If your AC ground rod is near by I would bury a bare copper conductor to connect to that ground rod also.

Is this a scanner your installing?
Thanks for the info. And yes I'm planning on getting a Icom R75.
 

jim202

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New Orleans region
There are a couple of reasons to ground your antennas. The first is that your home owners house insurance requires it. It would be best to ask them what their requirements are before you do much. They are the ones that will have to pay for any damages. If you don't do it to their specs, they really don't have to pay the claim.

Another reason is for personal safety. There can be a tremendous difference of voltage (potential) between metallic objects in your radio area and other electrical objects like outlets, appliances, air conditioner ducts and so on during a lightning strike. They all need to be bonded together with a common ground. this is why you keep hearing about making sure your tied to the same ground rod the electrical meter is tied to. Not to your breaker panel. The breaker panel is not the correct place to have the common ground.

The last reason is as others have said is the grounding section 250 of the NEC (national Electrical Code). It gives the guidelines on how grounding should be done at your house. The grounding rods and how connections should be made are spelled out. The grounding rods are steel with copper clad. You can find galvanized rods for special applications where electrolysis can be an issue.

One real important point to remember is that you don't want to drive multiple ground rods next to each other and then connect them all together. They need to be separated by twice their length. If yo use 8 foot ground rods, they should be 16 feet apart. This is due to the cone of influence around each ground rod. Spacing them closer will cause this cone to be intersected by the other ground rod. Doing this reduces the effective low resistance that each ground rod can contribute. If you have sandy soil, the ground rods will need to be longer and spaced further apart. It is not uncommon to have to use rods that may extend down to 20 or even 40 feet.

Grounding is a science and there are not that many people that really understand it. But you will find all sorts of know it all's that will provide information that is really lacking the truth behind it and engineering that good grounding requires. Make sure you know where the source of information you receiving is good. If your unsure, the Internet is your best friend. But you might have to do some hard searching to get the answer you should be getting.
 
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