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Author Topic: Station ground question.  (Read 21135 times)

Posts: 6252

« Reply #30 on: November 18, 2012, 07:50:26 AM »

Well first of all, thanks for all the replies and information from everyone.
This is an intense subject.
I suppose I could tie the two points together. 
The easiest path would be through the cellar, BUT THIS IS PROBABLY A NO NO, RIGHT?
I can run the bonding conductor outside along the perimeter of the house, it will just be more work.

The cable should be run outside the house, but if it can't be, the inside route can be used.  The main reason for tying the two ground points together is to equalize the potential between the two ground points.  In other words, the bonding together of the two is to prevent anyone who is in your shack from becoming that interconnection--and getting killed in the process.

Posts: 376

« Reply #31 on: November 18, 2012, 03:16:46 PM »

Thanks for the links guys - I have some reading to do. I think I might make some CAD drawings of the various home station grounding scenarios to have something more concrete to run calculations on.
early streamer emission (ESE)
I did some literature searching about ESE couple of months ago, and as far as I can find, there's no evidence that ESE actually can prevent lightning strikes from happening - as is often claimed by ESE proponents - or that they work better than regular air electrodes like points or balls. The only possible exception might be ground-to-cloud strikes from towers more than 300 feet high, for which there is simply insufficient evidence to show anything conclusively. The strike is going to come somewhere in the area - but with a lightning protection system you can try to help it strike where you want it to go.
My question is (and I have not seen this discussed) about how far away from the base of the foundation should that circle be spaced?  Would I place that ring of ground rods as close to the foundation as possible or is that critical?  
It should be outside the drip line of your roof - you want the ground ring it in wet ground. Or something like that. Here in Norway NEK 400 specifies 0.5 m away from the foundation.
« Last Edit: November 18, 2012, 03:40:08 PM by LA9XSA » Logged

Posts: 331

« Reply #32 on: November 18, 2012, 04:31:44 PM »

My question is (and I have not seen this discussed) about how far away from the base of the foundation should that circle be spaced?  Would I place that ring of ground rods as close to the foundation as possible or is that critical?

The Motorola R56 Site Standard referencess in Chapter 4 Part the following:

1)   Ground rings shall be installed in direct contact with the earth at a depth of 30 inches below grade, or below the frost line, whichever is deeper (ANSI T1.334-2002, section 5.3.1 and NFPA 70-2005, Article 250.53).

2)   Building ground rings shall be installed at least 3 feet from the building foundation and should be installed beyond the drip line of the roof (MIL-HDBK-419A and MIL-STD-188-124B).

3) Tower ground rings shall be installed at least 2 feet from the tower foundation (ANSI T1.334-2002, section 5.3.1)


Posts: 5482


« Reply #33 on: November 19, 2012, 12:45:49 PM »

I have the AplhaDelta polyphaser discharge devices (which won't do a thing for a direct hit, I get that point).

A popular misconception is that surge arrestors somehow have to divert, direct or dissipate a lightning surge.  Thinking like that, it's not surprising many do not believe their survivability.  The majority of the surge energy is on, and through the coax *shield* and antenna support structure to ground, not "through" the arrestor to ground.  The function of the arrestor is to clamp or isolate any surge coupled to the center conductor of the feedline, which is small in comparison. 

Mark K5LXP
Albuquerque, NM

Posts: 376

« Reply #34 on: November 19, 2012, 01:25:12 PM »

Yeah, more exactly the surge arrestor only has to deal with the voltage difference between the center and shield that remains when the strike comes to the entry panel. I suspect there's not much point in over-designing Polyphaser EMP arrestors to handle higher voltages than they already do since at one point the differential will spark through the coax dielectric, or jump acros the feed point anyway. Or turn it into a fluid.

A long run of (preferably buried) coax will work to limit strike energy all on its own, and is hopefully augmented by ground kits (connection from shield to the grounding system) along the way, so the arrestor only has to deal with any differential that remains.

On the flip side, if the lowest impedance path from the antenna to ground goes through the arrestor and into the house, it doesn't matter if you had the world's best arrestor there since the most of the strike will enter the house anyway - through the shield.

Now theoretically, even if you have the strike going through your station, if you have a ground system that ties everything together with low enough impedance, everything should rise in potential at approximately the same time, but I sure don't want to be there to test it out if it happens.  Wink

PS: I'm an engineer, but not an electrical engineer, so take the above with some salt.
« Last Edit: November 19, 2012, 01:27:54 PM by LA9XSA » Logged

Posts: 618

« Reply #35 on: November 19, 2012, 07:16:09 PM »

Thanks Martin,
I found a place to download the R-56 manual; now I've got some heavy reading to do.
The spacing from the building is a mixed blessing for me as that substantially increases the perimeter (and number) of the rods but, thinking about it, it should have been obvious to me.  I can see that this is going to be a lot more work that I had thought but I guess I can take it a little at a time.  I do want to keep my GPS frequency standard powered 24/7 so it needs to be done.
Again, thanks for the reply and reminding me of that very useful reference.

Posts: 30

« Reply #36 on: November 23, 2012, 06:46:43 PM »

I ended up running heavy gauge stranded wire( from the outside station/antenna grounds) to the water main connection which has the same run going to the load center panel.  I then added a ground rod to the already existing service entrance ground rod.

Here is a link to w8ji's very good website on station grounding.  Now my set up is pretty much close to the "best buy far" part of his site.

It was alot of work considering the rocky soil I have and the outdated logistical layout off my house.
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