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neonhomer
KK4BFN
Premium
join:2004-01-27
Edgewater, FL
Reviews:
·Bright House

Grounds in the ground....

Well... Now I am really freakin confused... The company I work for has a structured cabling division, and I was discussing my grounding needs for my antenna setup.

I was telling him that I needed four lengths of grounding rod, two couplers, and clamps. He was asking me why I needed such grounding. I explained that I needed one ground for the mast and one for the lightning protection plate. I was then telling him I had to tie these two grounds, plus the ground for the house electrical service.

These ground rods are all going to be within a 10' radius of each other.

He was telling me that I shouldn't tie these grounds together, as there would be a possibility of difference of voltage potential between the grounds. He was telling me that he saw a 25 pair cable melted together because of this...

I thought all three of these grounds had to be tied together.

So what's the right way to do this????
--
"F is for Fire that burns down the whole town...
U is for Uranium...... Bombs...
N is for NO SURVIVORS!!!!!" Sheldon Plankton

hardware bum

join:2004-01-26
State College, PA

1 edit
Tie them together. A potential difference will almost certainly exist if they are not connected. The point is to equalize the potential between all the grounds and the only way to do that is by connecting them together.

Imagine a near-by lightning strike and a large current through the earth between the ground rods. If they are not connected the instantaneous voltage between rods could reach several thousand volts due to even a small resistance in the earth. THAT'S how equipment and cables get fried. Learned the hard way.


John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
kudos:8
reply to neonhomer
All bonded together...


SmokChsr
Who let the magic smoke out?
Premium
join:2006-03-17
Saint Augustine, FL
reply to neonhomer
All grounds need to be bonded together!

Otherwise there will be a potential difference which will try to equalize through your equipment. It's not that critical that you have a good ground, but it is critical that you only have ONE ground. (multiple grounds bonded together are one ground)


49528867
Premium
join:2010-04-16
Fort Lauderdale, FL
kudos:3
reply to neonhomer
said by neonhomer:

So what's the right way to do this????

Here's one mans idea.

»One way of grounding an antenna..

Wayne
--
Madness takes its toll, please have exact change ready…


fox77

@uslec.net
reply to neonhomer
You tie them together so there will be NO potential difference between them. That difference will look for a way to become at equilibrium and the path, if they are not connected, is through your equipment.

fox77

utahluge

join:2004-10-14
Draper, UT
reply to neonhomer
I should try to find the Army grounding manual I have somewhere. We ALWAYS tie grounds together when within a certain distance. Just don't tie your power and RF grounds together. Make sure they are far enough apart to not have to tie together.


SmokChsr
Who let the magic smoke out?
Premium
join:2006-03-17
Saint Augustine, FL
said by utahluge:

Just don't tie your power and RF grounds together. Make sure they are far enough apart to not have to tie together.

Don't care what the Army said who knows how long ago.. To prevent lightning damage there can be only 1 ground. To not do so (especially if they are separated by a distance) is to invite magic smoke releases.

The RF ground absolutely needs to be bonded (bonded means tied very solidly together through an adequately sized conductor) to the power ground. The RF ground and power ground are often 2 different systems, primarily because a protection ground doesn't make a good RF ground, nor does a RF ground make a good protection ground, but they should be bonded to make a complete system.

PS note I'm a broadcast engineer in Florida, I get ample opportunities to verify lightning system protection, on towers ranging up to 1300'.


LazMan
Premium
join:2003-03-26
canada
There are specific cases where you don't ground certain RF equipment... It's designed to be floating, and great care has to be taken to maintain that isolation... I've got a couple of old analog radio locations (for telcom use) that are still setup that way.

That said, those are very SPECIFIC situations... Generally you want everything bonded. You can, and often should have multiple ground points, but they must be combined into a common plane, as well...

Grounding vs grounded vs bonding can become very confusing, very quickly...

UncleDave

join:2009-01-08
Florissant, CO
reply to SmokChsr
This subject is wide open. Used to work in Broadcasting. My rule of thumb was that you could never have too much grounding. A heavy ground cable is good. How about two? There is the Neutral, and Case ground. They are the same, right? When these get reversed it can cause problems. It took me Weeks to find some problems. I would try to put in as many paths to ground, try not to make one of these YOU.


neonhomer
KK4BFN
Premium
join:2004-01-27
Edgewater, FL
Reviews:
·Bright House
reply to neonhomer
Okay... Didn't know if I specified my setup or not....

20' push up pole. Push up will be anchored to a 6x6x12 timber (that is buried in 6'of concrete.) at multiple points. Arrow J-pole on top. Also, there will be a pulley at the top of the push up to allow the G5RV to be drawn to it. Pole will be approx 8' from the side of the house.

Coax will be run down the side of the pole to roof level, then run across to the eave, then down the side of the house to my bonding plate. Coax will then run from lightning protection (two separate devices.. one for HF, one for 2m/440) inside to radio.
--
"F is for Fire that burns down the whole town...
U is for Uranium...... Bombs...
N is for NO SURVIVORS!!!!!" Sheldon Plankton


Hank
Searching for a new Frontier
Premium
join:2002-05-21
Burlington, WV
kudos:3
In large buildings everything is tied to building ground.


burner50
Proud Union THUG
Premium
join:2002-06-05
Fort Worth, TX
kudos:1
reply to neonhomer
Always tie them together, otherwise, the electrical system in your house might start using your radio as a ground.


battleop

join:2005-09-28
00000
reply to neonhomer
Some of the old hams I know have always told me 1 ground or no ground. Never ever have more than one because your equipment will at some point become the bridge between the multiple grounds.

Your co-worker is correct about the difference in grounds but he is wrong about not connecting them together. Not connecting them together is what caused the 25 pair to melt. The 25 pair at some point in time was grounded on each side and then the 25 pair became the bridge between the two grounding systems.
--
I do not, have not, and will not work for AT&T/Comcast/Verizon/Charter or similar sized company.


jmpenguin
Jmpenguin
Premium
join:2004-01-16
Labelle, FL
Reviews:
·HughesNet Satell..
reply to 49528867
As you know I live in the lightning capital of the USA. Proper grounding is a requirement. We were installing a new alarm system, a storm hit, power went out however when ever lightning struck several miles away the LEDs on the panel lit up.
Remember the good old days?
--
Comcast HSI or AirCard either Sprint or ATT WINXP-Pro, LAN Firefox Thunderbird Gmail


SmokChsr
Who let the magic smoke out?
Premium
join:2006-03-17
Saint Augustine, FL
said by jmpenguin:

We were installing a new alarm system, a storm hit, power went out however when ever lightning struck several miles away the LEDs on the panel lit up.

Amazing what induction can do. For an more dramatic example, just drop by an AM radio station with a guyed tower as a thunder storm approaches. You'll hear the discharge jumping across the guy insulators, every time a strike happens within about 15 miles.