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Author Topic: New Station 2nd Floor Ground Setup  (Read 1905 times)
MEHAM
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Posts: 14




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« on: April 17, 2011, 12:22:29 PM »

I have read many different articles regarding grounding (RF, electrical, lighting), I'm hoping to get some human feedback about my plans for a new station to see if it makes sense and to get any input/advice from more experienced folks.

Shack will be on the second floor.  I will ground all equipment to a copper ground bar inside which will be connected to a Window FeedThru (possibly one of the MFJ ones).

I will use coax lighting arrestors on the outside of the feedthru where the incoming coax will connect into it.

The feed thru panel will ground (6 gauge or heavier wire) down along the side of the house to a new ground rod I will put into the ground 16 ft from the existing electrical ground rod.

I will bond this new ground rod to the existing electrical ground rod.

There will be two antennas (initially):
1. VHF/UHF antenna mounted on the roof, on a tripod with a mast
2. Alpha Delta wire antenna hung from the trees

Q: Do I need to separately ground the tripod/mast in addition to the coax being grounded to the feed thru?  If so, how should that be grounded; to the feedthru panel or separately direct to the new grounding rod?

Q: If I will be bonding the new ground rod to the existing electrical ground rod; what is the reason I can't just use a single ground rod for everything since they will be connected together anyway?

Resources:
http://www.arrl.org/grounding
http://www.arrl.org/lightning-protection
http://www.mfjenterprises.com/Search.php?searchit=feedthru

Thanks in advance for your responses!

Louis
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K1CJS
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Posts: 6034




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« Reply #1 on: April 17, 2011, 01:15:54 PM »

In general, what you have in mind is good from a safety grounding point of view.  If you are in an active lightning storm area (you don't specify your location in your profile) it would make VERY good sense to also ground the tripod/mast on the roof to your ground rod.  You may be better off with a separate shack ground rod bonded to your electrical mains ground rod.  More is better than less in this instance--especially if you're in an active lightning storm area.  AAMOF, I would consider a couple more ground rods, spaced about 16 ft apart from each other to dissipate any static charges better.

RF grounding?  Your Alpha-Delta antenna doesn't need one since it is a dipole, and your VHF/UHF antenna shouldn't need one either.  You can disregard any notion you may have of needing an RF ground.
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K3AN
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Posts: 787




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« Reply #2 on: April 17, 2011, 03:46:56 PM »

Be sure that any ground rods you install are all connected together with heavy wire (#8 is sufficient) AND ALSO connected by heavy wire to the electrical service ground rod. Even it that ground rod is on the other side of the house.
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K1CJS
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Posts: 6034




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« Reply #3 on: April 17, 2011, 07:13:37 PM »

It may be sufficient, but I don't think to the NEC standards.  I believe they call for number 6 cable connecting the ground rods togetner.
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MEHAM
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Posts: 14




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« Reply #4 on: April 17, 2011, 09:15:28 PM »

K1CJS: The shack will be up in Maine, it looks like the area is relatively minimal for lighting compared to most of the US (http://www.lightningsafety.noaa.gov/lightning_map.htm) if this URL can be believed anyway.

What do I gain (or loose) by running the ground directly to the existing ground rod that the electrical service panel uses in the ground?  I know from what I read I should add an additional ground rod to run the window feedthru and antenna mast to; I am just not sure all the details as to why since the new ground rod and service ground rod will be bonded in the end anyhow.

I am going to use #6 or bigger wire for all the ground runs.

L

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KB1VCZ
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Posts: 30




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« Reply #5 on: April 18, 2011, 11:31:43 AM »

K1CJS: The shack will be up in Maine, it looks like the area is relatively minimal for lighting compared to most of the US (http://www.lightningsafety.noaa.gov/lightning_map.htm) if this URL can be believed anyway.

What do I gain (or loose) by running the ground directly to the existing ground rod that the electrical service panel uses in the ground?  I know from what I read I should add an additional ground rod to run the window feedthru and antenna mast to; I am just not sure all the details as to why since the new ground rod and service ground rod will be bonded in the end anyhow.

I am going to use #6 or bigger wire for all the ground runs.

L




You are hitting on a number of issues I'm working through right now.

I guess if you have more ground rods the better off you are, but these separate ground sub systems need to all bond together and then to the AC main ground rod to form a complete system SPG.

In my case I will likely have one ground rod which will be the ac ground rod at the meter, but everything else will be connected to that ground path in the end (see my thread on bonding to the AC panel direclty).
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K1CJS
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Posts: 6034




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« Reply #6 on: April 18, 2011, 12:45:10 PM »

One thing you want to keep in mind is that electrical energy will follow the shortest path to ground, but it will also follow the easiest (less resistance) path.  The more ground rods you may have, the more the chance the charge will not end up jumping the intended ground path (through the ground cable into the rod and the ground) to another ground path. (say like to your electrical panel ground bus and into the house wiring while looking for that ideal path)

Although Maine isn't as lightning prone as warmer climates, there can be some pretty bad storms up there, along the coast.  I'm in Southeastern Mass. myself, and although I've never been directly hit, I've seen damage that has resulted from a lightning hit.  One such example was a charge actually jumping from the electrical ground cable to a water pipe that led to a well.  The water pump motor was blown and the wiring to it was crisped too, as was some of the house wiring.

Usually, the more ground rods you have in, the better protected you will be.

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