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Author Topic: Grounding & Ground rods  (Read 1158 times)
K3ASA
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Posts: 137




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« on: August 18, 2005, 01:59:34 PM »

My new shack will be on the same ground level as the house ground rod, (downstairs) but, unfortunately about 45 feet away, with a 90o turn around a corner of the house included. My questions: First: Will a ground rod outside, near my shack, (a few feet away from the rig) and then a series of rods, connecting each to each other by a #4 copper wire, and eventually connecting to the house ground, work well?  Second, how far apart should the rods be?  I see 8' between rods suggested, and also see  16' between rods   suggested.  Finally, shouldnt the rods be 8' long?  I see MFJ selling 4' rods for grounding...(?) Will these "shorties" work OK??  My soil here is 12"-15" of loamy topsoil, and then ENDLESS Red Clay, which is like Playdough when wet, and when dry, well, lets just say they make BRICKS out of the stuff! Its damned near Impossible to get a 8 footer down through that stuff.  Any advice... comments??  Really dont want to move the shack closer to the house ground unless absolutely necessary.. Thanks!  73 de K3ASA
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WB2WIK
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« Reply #1 on: August 18, 2005, 02:25:50 PM »

What's the ground for?

Only knowing exactly what the intended function of the ground is can determine how it should be implemented.

4' might work, but 8' is the code requirement (NEC) as a minimum length.  Hams can do whatever we want but contractors must use at least 8 feet.  

Most people have soil/earth that makes it very difficult to slam an 8' rod directly into the ground; but then, that's the whole idea.  If the rod goes in easily, it cannot be making good contact with the earth.  It's supposed to be almost impossible to get in.  

WB2WIK/6
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K3ASA
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« Reply #2 on: August 18, 2005, 02:50:45 PM »

The ground is for all of my equipment in the shack, my transceiver, power supply, tuner, etc., all of which will be grounded/bonded together to a copper bar on the back of the bench. Then I'll run a copper strap from that copper bar, to the ground outside I was asking about.
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WB2WIK
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« Reply #3 on: August 18, 2005, 03:18:58 PM »

No, I meant *exactly why* are you grounding things?  What's the purpose to be fulfilled by the ground connection?

The answer to this question dictates what kind of ground is appropriate.

Volumes have been written on this subject, including some here, and some very recently, like:

http://www.eham.net/forums/Elmers/97102
http://www.eham.net/articles/8951

...and a lot more.

WB2WIK/6
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K3ASA
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« Reply #4 on: August 18, 2005, 04:40:50 PM »

WOW!  I actually read most of the articles you referenced..  Now  ~  I believe my brain has turned to mush..  What a bunch of differing opinions.   OK...OK... (I guess..)  MY ground is gonna be for safety reasons, for lack of a better reply to your query..  
Now, a really dumb question:  HOW do I ground my antennas outside of the entrance point to the shack? (Lightning ground, I guess it is..)  One will be an rooftop open loop, probably fed with coax, the other will be a verticle, in my back yard, fed with coax. Whats the best way to ground these for lightning protection.. I still intend to unplug all equipment before storms, and disconnect antennas.. (Not sure about the mason jar thing, though.. hahaha...)   Thanks..  73 de K3ASA
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WB2WIK
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« Reply #5 on: August 18, 2005, 08:09:09 PM »

You can do lots of stuff.

With coaxial feedlines, you can ground the shield of the coax before it enters the house.  Not only "can," but "SHOULD."  You can also use coaxial lightning suppressors as sold by many companies from Alpha-Delta to I.C.E. to Polyphaser to anybody (!). Those are through-line coaxial fittings having discharge-type lightning arrestors inside them; many of them use replaceable or resettable elements, so they can be used an re-used repeatedly.  In any case, to make these things work they must be directly connected to a very close, low-impedance ground *OUTSIDE* the house.

Some verticals are already "DC grounded," meaning the main radiating element is at ground potential, same as the support mast.  In such cases, ground the mast well and you've essentially grounded the whole antenna.  It still pays to use bulkhead grounding (grounding the cable shields prior to house entry) and/or coaxial lightning arrestors installed at the "shack" end of the cables, but still *OUTSIDE* the house.  And in either case, they must be well grounded, and a #6AWG minimum ground conductor wire must bond from that ground point to your electric service panel ground, by code.

Never use any arrestors inside the house.

Disconnecting everything, having good fire insurance, and going on vacation during each lightning storm is a great idea...

WB2WIK/6
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K3ASA
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« Reply #6 on: August 19, 2005, 06:52:54 AM »

OK.. Many thanks... but I am still uncertain as to "How" I physically ground the coax shield. How do I perform that task, I guess I mean to ask? Sorry, I am such a pain.  I REALLY appreciate your help. I just dont know how to go about grounding the coax shield. How do I attach it (them) to the ground?  Thanks... 73 de K3ASA
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WB2WIK
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« Reply #7 on: August 19, 2005, 08:02:51 AM »

Look up *any* brand coaxial lightning arrestor product, which are many, and you will immediately see how this is done.  The arrestor splices into the coaxial cable (using mating connectors) and the arrestor has a big, fat GROUND terminal, screw or lug on it that connects directly to ground, preferably bonding directly to an 8' ground rod or an array of interconnected 8' ground rods.  They come with instructions.

Without the arrestor, to just ground the coaxial cable shield(s), all you need is a bulkhead panel with double female coaxial bulkhead connectors on it.  Mount that panel outside, or in a window or other entryway to the house.  Attach a big, fat ground conductor directly to that panel, using bolt/lockwasher/nut hardware.  Screw antenna feedlines into the bulkhead connectors, and on the "inside" end of each bulkhead connector, attach a short coaxial line that runs to the station equipment.  Because the panel is grounded, now so are all the coaxial cable shields.

Several companies sell these, too.

WB2WIK/6
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K3ASA
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Posts: 137




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« Reply #8 on: August 19, 2005, 11:27:33 AM »

OK... Got it Now!  Many thanks for your Info AND your PATIENCE!  Sometimes I cannot "see the trees for the forest".  I really appreciate it!   73 de K3ASA
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K3ASA
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« Reply #9 on: August 19, 2005, 11:45:44 AM »

Thanks... Finally, is it just personal choice, or which will do the better job?  The Bulkhead connector sounds great/neater/easier, but is the protection as good as using a couple arrestors?  73 de K3ASA
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WB2WIK
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« Reply #10 on: August 19, 2005, 12:05:49 PM »

People who live in high lightning incidence areas often use "both," arrestors and bulkhead grounding.

One great thing about an entrance bulkhead panel is that it's a convenient "disconnect" point: If you're going away and expect any lightning, just unscrew all the antenna connectors outside the bulkhead and toss them on the ground.  Now, at least anything that happens...your feedlines are completely outside the house where they're very unlikely to do any damage.

Here in Los Angeles, where I've only actually seen lightning once in 17 years,  I don't worry much about this stuff...

WB2WIK/6
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K3ASA
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Posts: 137




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« Reply #11 on: August 19, 2005, 02:35:03 PM »

Yep... That was the first thought that hit when I looked at one of the bulkhead panels I see for sale. Very easy to disconnect and be TOTALLY outside. I like the bulkhead idea and might skip the arrestors.
BUT  ~   We DO have a LOT of summer lightning/Electrical Storms here in SC, and at times it gets REALLY WICKED.. perhaps I can manage both, in case I forget to disconnect.   Kinda like one of those "HMMM... did I leave the darn stove on??", when you have already gone 50 miles from home! You worry a lot until you get back...  Again, Thanks, I appreciate your time and shared knowledge.. Sorry I was such a pest.  73 de K3ASA
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WA5UHK
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« Reply #12 on: August 25, 2005, 07:26:58 AM »

You need at least an 8' rod because you have to connect the ground you are creating for your rig to the ground that is located at the service enterance of your electricity provider.  You don't want two grounds "fighing" for current dumped into them by a fault; if they are different, one will rise above the other....not good for your rig or your other appliances.

If you really want to understand the quality of the ground at your location; measure it.  You can buy & read, "The Short Vertical Antenna and Ground Radial"  (subtitled "Design, Theory, and Construction for HF Systems that work")  by Jerry Sevick, W2FMI
- Publish by CQ Communications, 2003.  It only cost 10 bucks and you can get it at  http://www.amidoncorp.com/aai_bookshop.htm

This book has a schematic for an instrument to measure your local ground.  Its pretty simple and all you need is some light bulbs as ballast, a power cord, misc. passive components and an external voltmeter to plot your ground over a period of a couple of months.  You won't have to wonder anymore if you measure...
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W4TME
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« Reply #13 on: August 25, 2005, 09:02:58 AM »

If you live in SC (I live in NC), I recommend you get the ICE arrestors along with the bulkhead. The biggest problem you can have is...

1.) You forget to disconnect the coax
2.) A near strike with the coax connected can fry your equipment from the EMP (electromagnetic pulse) that the strike produces.
3.) Wind and snow (we do get a little of it) cause static buildup on your antenna system and that static needs to be discharged to protect your rig.

FYI, most rig damage is not caused by a direct lightning strike.

They are not that expensive and are much cheaper than replacing or repairing your rig.

-Tim
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K3ASA
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Posts: 137




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« Reply #14 on: August 26, 2005, 10:41:50 AM »

THANKS for ALL of the Great Replies!  Gene
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