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Author Topic: Grounding Question  (Read 4372 times)
NZ4Z
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« on: April 22, 2013, 07:24:26 PM »

Yes....I know there are threads out there on this topic, but I am the dumbest Extra you will ever meet (about Ham radio). I'm not good with all the technical terms....so......I just bought a new home and the shack is going in to the bonus room, 2nd floor over garage, and master BR. So.....how do I get a proper ground? A buddy says run a 5 inch wide ground strap down to 2 ground rods, then attach to bus bar in shack, connect from there? My last home, shack was on ground floor, ran 8ga out window to 1 ground rod. When I keyed amp at 700W or more.....TV's started going out! I don't want that problem here. Then I see people saying something about grounding at the main power entry of the house......just shoot it to me in simple language......what to do?

Thanks in advance!

73'

Steve / NZ4Z
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VA7CPC
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« Reply #1 on: April 22, 2013, 08:53:21 PM »

If you run an amp, and your antenna is close to the house, no amount of "grounding" is going to save you.   That power is being radiated, and some of it will get into the house.

Chokes on the power lines, AC cords, and TV lead-in wires (or cable-TV coax) _might_ help.

And next, what kind of "ground" are you talking about:

. . . AC power-line ground?

. . . lightning ground?

. . . RF ground for an unbalanced antenna ?

The station should be considered _as a whole system_ before you start running copper.

.               Charles

PS -- If you have an Advanced license, you might have an ARRL Handbook lying around.  There's a lot of material there about grounding systems.
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KA4POL
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« Reply #2 on: April 22, 2013, 09:33:15 PM »

If you are a member of ARRL: http://www.arrl.org/grounding
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WA3SKN
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« Reply #3 on: April 23, 2013, 04:59:16 AM »

There are three reasons for grounding.
The AC or safety ground.
The DC or lightning protection (mislabelled).
The RF counterpoise.

Now where is the AC entrance panel located in relation to the room you wish to use, and what type antenna and where will it be located?  (And why do you think that the ground is related to TV interference?)

-Mike.
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W6EM
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« Reply #4 on: April 23, 2013, 05:32:16 AM »

Whatever you do, connect any supplemental grounding system to your electrical service entrance grounding electrode (fancy name for ground rod or other code-permissible means).  Your safety and that of your family is paramount.

The National Electric Code (NEC) requires the interconnection for a reason.  (Not that the NEC minimum for grounding electrode ground resistance is OK.....it's 25 ohms!!!)  Primarily for lightning protection, but also for protection from stray high voltage ground currents from utility high voltage malfunctions.

Separate grounds can have differences of potential depending on current flow through them.  In the case of a nearby or direct lightning strike, it could be thousands of volts.  What that would mean is, for a few milliseconds, your isolated-grounded ham equipment could be thousands of volts above or below everything else grounded to something else.  So, tie the grounding systems together and do so very near your main panel.  Actually, attach them to the probably AWG No. 6 or No. 4 solid copper wire from your panel to the existing grounding electrode.  And, use connectors that are listed for the purpose (UL labelled for copper to copper, like what are commonly called "split bolts" or "acorn" connectors)

As for size, make it at least the same size of solid copper wire used for the grounding electrode conductor.  And, it needs to be a straight, direct run to the supplemental rods you've installed.  And, you should use a UL-listed ground rod clamp with tap to interconnect them.  You can then run what you choose from that interconnecting conductor up to your ham shack.  Admittedly, if you want minimum reactance per foot, the advice your friend gave you, a straight run of flat strap, would probably be the best....
« Last Edit: April 23, 2013, 05:35:44 AM by W6EM » Logged
K5LXP
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« Reply #5 on: April 23, 2013, 06:06:19 AM »

Of the hundreds of "grounding" threads on this forum I think this one hit all the points in the fewest responses.  Thinking maybe we could combine them into one and then use it as a boilerplate response, saving everyone the time and trouble of repeating themselves every week.


Mark K5LXP
Albuquerque, NM
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KD2CJJ
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« Reply #6 on: April 23, 2013, 06:23:11 AM »

Question, how could I measure that my main ground is a minimum of 25 Ohms?

Whatever you do, connect any supplemental grounding system to your electrical service entrance grounding electrode (fancy name for ground rod or other code-permissible means).  Your safety and that of your family is paramount.

The National Electric Code (NEC) requires the interconnection for a reason.  (Not that the NEC minimum for grounding electrode ground resistance is OK.....it's 25 ohms!!!)  Primarily for lightning protection, but also for protection from stray high voltage ground currents from utility high voltage malfunctions.

Separate grounds can have differences of potential depending on current flow through them.  In the case of a nearby or direct lightning strike, it could be thousands of volts.  What that would mean is, for a few milliseconds, your isolated-grounded ham equipment could be thousands of volts above or below everything else grounded to something else.  So, tie the grounding systems together and do so very near your main panel.  Actually, attach them to the probably AWG No. 6 or No. 4 solid copper wire from your panel to the existing grounding electrode.  And, use connectors that are listed for the purpose (UL labelled for copper to copper, like what are commonly called "split bolts" or "acorn" connectors)

As for size, make it at least the same size of solid copper wire used for the grounding electrode conductor.  And, it needs to be a straight, direct run to the supplemental rods you've installed.  And, you should use a UL-listed ground rod clamp with tap to interconnect them.  You can then run what you choose from that interconnecting conductor up to your ham shack.  Admittedly, if you want minimum reactance per foot, the advice your friend gave you, a straight run of flat strap, would probably be the best....
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73

Mike
KD2CJJ
W6EM
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« Reply #7 on: April 23, 2013, 06:46:41 PM »

Question, how could I measure that my main ground is a minimum of 25 Ohms?


By using an instrument designed to measure it.  The easiest way would be to borrow or rent a clamp-on digital ground resistance meter. (Price is about $1,500 to buy one).  They inject high frequency current in the grounding electrode conductor-earth circuit and determine resistance.  The circuit consists of earth to ground rod to main panel to utility neutral to utility transformer ground rod to earth.  A cheaper way would be to use what is called a fall of potential ground resistance tester.  Less expensive, but, unlike the clamp-on type, would require you to disconnect the ground rod from your panel.  Not safe to do so without first disconnecting power at your main panel.

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K4RVN
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« Reply #8 on: April 23, 2013, 08:27:34 PM »

Steve,
I would suggest that you buy a field strength meter off the internet, or Radio shack etc.  They are available for 30 bucks or less and you don't need an expensive one. The second floor presents more problems than the first floor shack. What ever you do run a ground from each piece of equipment to a single tie point. Then go from there to an outside ground rod. Don't daisy string your grounds on the equipment. I am talking about RF grounding here, not lightning protection just to set all the purist straight. The field strength meter will alert you to RF in the shack so you won't have to guess if your grounding system is working. I keep one hanging on the wall by the coax going to my antennas. If a solder joint or something is not right or a ground is loose the field strength meter indicates  RF is floating around in the shack. I also use a 915 MFJ line isolator on my coax at the transceiver to stop my coax from putting rf into the shack. I run two amps, two transceivers. It is more or less trial and error on a second floor shack while maintaining good practice for each grounding scheme. The field strength meter will let you know if you are OK
You did not mention your antenna set up and that plays a large part of your grounding success.

Frank
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K1CJS
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« Reply #9 on: April 24, 2013, 03:52:11 AM »

Of the hundreds of "grounding" threads on this forum I think this one hit all the points in the fewest responses.  Thinking maybe we could combine them into one and then use it as a boilerplate response, saving everyone the time and trouble of repeating themselves every week.

There are always answers in these fora for just about everything under the sun to do with ham radio.  This subject is one of the ones that you wouldn't have to look far to get the answers you need---but people still start a new thread instead of looking for the answer in the first place!  Just look at the first sentence of the first post in this thread.

Even if this were to be made a sticky, you would find the same questions posted in a new thread almost every day.  Until the rock bound dumbbells stop doing that --and also stop posting the same question in every forum that they think applies, there's going to be a lot of time wasted--and there is nothing to be done about it!
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KD2CJJ
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« Reply #10 on: April 24, 2013, 10:42:55 AM »

What about grounding to a water pipe?  This was the only option I had as my shack is also on the second floor without the possibility of using my ground rod outside my electrical panel.  I of course could run the wire up my house through the attic but that would be over a 50 foot run - would that be better than just grounding all my equipment to my water pipe that is 4 feet from my equipment?

I can say though, I was having major RF issues until I grounded it to the water pipe.  Not that it is perfect but none of my electrical equipment acts weird since attaching to a water pipe (like my mouse/pc locking up, the AVS being triggered in my UPS, voice heard in external speakers, voice heard through speakers in the next room and living rooms on TVs, etc.) and RF over voice during transmit ... that is all gone now.  Do you think that could be hurting receive performance in anyway?
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73

Mike
KD2CJJ
K5LXP
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« Reply #11 on: April 25, 2013, 10:06:52 AM »

I was having major RF issues until I grounded it to the water pipe.

Let me give you a few points to consider. 

If your station has so much RF to cause "major" RFI issues, your station, intended or not, is part of your antenna. 

Indoor antennas put strong fields of transmitted RF into equipment that may not tolerate it- PC's, TV's, etc.  On receive, your antenna is effectively adjacent to sources of EMI, like switching power supplies, computing devices, etc - whatever is plugged in to the mains or operating near the rig. 

The prevailing wisdom when you have "RF in the shack" is to "ground" everything.  So, you connect your chassis (antenna) to "ground" (a conductor with length and RF current, or "antenna") and suddenly everything works better. 

But what just really happened?  You took your station antenna and connected it to another antenna through your chassis. Symptoms change because your chassis is now at a different node in this antenna system.  The energy has been diverted somewhere else - lost to heat, useless radiation and the remainder to head out in useful directions via the antenna outside.

Understand - ground rods are not, cannot be and never will be an RF ground.  Any conductor used in an attempt to "ground" RF to an outside ground will only ever be an antenna.  You cannot shield or otherwise prevent a ground conductor from radiating.  Grounding your station in this way may change the path of the RF and cure an RFI symptom but it's not solving the root problem of the common mode condition in your system. 


Quote
What about grounding to a water pipe?

Water pipes for safety grounds are no longer per NEC because of the widespread use of plastic pipe.  Even if all the pipe in your house is metal, you don't know what the utility used out to the street so your "pipe ground" could essentially be floating in the structure.  From an RF point of view you are merely effecting the above, turning your water pipes into a lossy antenna.  Yes, sometimes this helps because it may solve a symptom but the better way to fix it is to solve the common mode issue.


Mark K5LXP
Albuquerque, NM
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KD2CJJ
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« Reply #12 on: April 26, 2013, 06:02:09 AM »

Last weekend I did change my antenna, it is now a mini beam raised to about 33, which is now above my roof line.  Before it was a wire dipole hanging off the side of my house -  I have not tried unhooking all the grounds to the water pipes...  I guess I ask because I typically get better responses of my signal (59+10) but my receive just doesnt match... That same station will be usually a 57 or a 58.  

Could my improper RF ground contribute to the differences between receive and transmit?  


So I guess the question is, which is on the theme of the original post, how do you create a proper RF ground if you are on the 2nd floor or higher of a house?  I always see responses which talk about the ideal condition, but almost never when the issue is in a less then ideal (and I typically see arrogant response like move your shack to the basement; so I particularly don't want to see any of those nonconstructive "answers").  
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73

Mike
KD2CJJ
AA4PB
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« Reply #13 on: April 26, 2013, 06:53:13 AM »

If you use a balanced antenna like a dipole or a Yagi then you shouldn't need an RF ground. Of course, if the antenna is close to the house then you may have direct coupling of the RF radiated from the antenna getting back inside the house. Also if you are not careful to route coax so that it doesn't run parallel to the antenna close by then you could have RF coupling back into the shield.
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K5LXP
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« Reply #14 on: April 26, 2013, 06:59:46 AM »

how do you create a proper RF ground if you are on the 2nd floor or higher of a house?

Simple answer - you can't.  A "proper" RF ground is at the antenna feedpoint, not at the equipment unless you don't mind the equipment being part of the antenna.

An antenna like your mini beam is a ground-independent antenna and doesn't require any kind of separate radial or counterpoise structure to operate.  No "RF ground" necessary.

RF grounds are for antennas, not equipment.  If you decide to use an antenna that requires one and put the RF ground at the station  instead of the antenna feedpoint (intentionally or unintentionally), then you're going to make the station part of the antenna system/RF ground.  People do this all the time and often don't experience any interference problems.  But when they do, suddenly it's a "grounding problem" when in fact it's an antenna problem.


Quote
I always see responses which talk about the ideal condition, but almost never when the issue is in a less then ideal (and I typically see arrogant response like move your shack to the basement; so I particularly don't want to see any of those nonconstructive "answers").

It may come off as arrogant but there is a harsh reality known as physics.  You're not going to change how antennas and RF behave to fit an individual's operating constraint.  All you can do is accommodate it best you can.  Specifically, if you are operating above the earth you should either pick antennas that aren't ground dependent, or keep the RF ground at the feedpoint of ground dependent ones.  The use of baluns and ununs can help with third wire and coupling effects to minimize RF currents on feedlines and equipment.  Consider that antennas and equipment work on airplanes and satellites without the benefit of a copper strap connected to a rod stuck in the earth.  Things can work equally well in a 2nd floor shack.


Mark K5LXP
Albuquerque, NM
« Last Edit: April 26, 2013, 07:08:58 AM by K5LXP » Logged
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