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earth ground questions ???

  • Thread starter Thread starter BOOTY MONSTER
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BOOTY MONSTER

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is burying several large copper wires (10 ft or so long) or small diameter copper pipes a few to several inches in the ground so they spread out from the base of a mast better than a single ground rod buried in the ground ? from what i understand a single ground rod isn't a effective earth ground .
 
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If you had to conduct millions of volts that has a several hundred thousand amps behind it; just how much surface area of metal would you need in the ground - and feeding it - to ensure that none of the conductors heated up and fail during a strike.

My answer: very large gauge wire(s) feeding five 8 ft ground rods or pipes using the same gauge wire to interconnect them. Spaced about 10 ft apart or more.

I hope that sums it up.

Great question though . . .
 
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The "signal" (is that supposed to be "single"?) 8-foot ground rod, installed in undisturbed soil and bonded properly to the ground rod at the electrical service entrance, complies with the NEC requirements. Depth of penetration is the key, not area.

If you're looking for lightning protection, there's WAY more to it than just ground rods.
 
thanks robb .
yes i meant single beetle . are you saying i should bond the mast/antenna to the ground rod installed at the power meter provided by the electric company here ?
 
BOOTY MONSTER said:
thanks robb .
yes i meant single beetle . are you saying i should bond the mast/antenna to the ground rod installed at the power meter provided by the electric company here ?
Click to expand...
What I'm saying is that the NEC REQUIRES it. And they specify 6 gauge wire or larger, if I remember correctly. It's all about keeping all grounds at the same potential.

Wavrider posted a couple of pretty good links.
 
there's a lot of info on them links wavrider , thanks .

thank you too beetle . the meter is about 9-10 ft from where the base of the mast will be . my coax is gonna be running in the same direction .... is it ok to run them together ? or should i separate them ?
 
I think I'd separate them as much as possible. No point in inducing it into the feed line if it isn't necessary, or creating the possibility. Then, if it's possible to move the house over a few feet, that'd work too, wouldn't it??
- 'Doc
 
doc , since the coax will be zip-tied to the mast and the mast will be the conductor between the antenna and ground wire ..... would "it" (i'm guessing "it" is potential current from a lightning strike) already be introduced into the feed-line ?
 
Well now I'm confused Booty. I was now under the impression that your questions were concerned about home electrical/NEC requirements and not strikes.

Don't think for a moment that if you were to isolate the coax from the mast that it wouldn't conduct a lightning strike into the radio and shack. That would be dangerous and underestimating the threat potential. To understand what happens in a strike, if your house/antenna is hit - then there is a strong possibility that your neighbor's house will get hit too. Lightning isn't a single bolt; but a series of multiple discharges that will move along a short distance. It actually moves across the ground surface. You can see this effect if you watch some slow motion films of lighting strikes (check out 'YouTube'). A 3 or 4 inch spacing between the coax and the mast WILL DO NOTHING to stop, resist, or even slow down these discharges. Or 3 or 4 ft for that matter.

You live in VA; just be glad that that you don't live in FL. But VA gets a healthy share of strikes too. In CA - it is relatively rare. I can see how you would be concerned about lightning.
 
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yep , just figuring out how i want to ground this antenna . i'm pretty good about disconnecting the coax inside if it looks like bad weather is coming or forecast . i also disconnect it if im gonna be gone all night . i do forget sometimes or dont realize its bad weather out till i hear a rumble , and some day my luck will run out :crying: . i never grounded my 1/4 wave or 5/8s and never had any problems , but this one will be about 50 ft to the tip . i have lots of big oaks here and huge towers out back for the power lines .

Google Maps

the power lines behind the school also run behind the house ....... havn't had any noise issues with them yet ...... surprisingly .
 
Booty just get the best ground that you can get as far as DC ground.

If you can get a couple of ground rods sunk at the base of the antenna mast, then put a copper plate or aluminum plate between the two ground rods, mechanical connection , a feed through connector for your coax. Then ground potential will be at the base of your antenna mast and not at the house.

Ohms law, current seeks the least path of resistance to ground.

By grounding it at the antenna mast it gives the least path of resistance to ground.

Of course putting a few more ground rods in the ground and connecting them with some fat copper wire just gives a better ground. Better is good?

If not using your equipment, unplug it, and disconnect the coax. If nothing is connected to your equipment, coax or electrical wise then no damage to be done per say.

Any ground is better than no ground.
 
I don't agree with everything 'JI' says, but those two links are pretty good. As far as grounding fir safety, do you want to satisfy the 'legal' requirements or really protect your equipment? They are not the same thing at all (legal requirements as in insurance and local ordinances). How well a grouns system works is primarily dependent on the 'dirt' in your area, that's something that also isn't the same everywhere. -Sometimes- depth is a pertinent factor, but most times it isn't. A ground radial has to be deep enough so that you don't trip over it or wind it up in the lawn mower. Unless you happen to live on really dry sandy soil or the desert, you know? In situations like that, you'd be happiest plating the sand with copper (please take pictures??). The idea is to dissipate or transfer energy from what ever you're grounding to someplace other than that 'whatever', at a low resistance. Larger conductors would be nicer at that, but lots of smaller conductors will do the same thing. FWIW, electric fence wire is of adequate size (but more radials are required) and it's fairly cheap, typically sold by the 1/4 mile. It's also usually galvanized and can be a real PITA to solder/bond. How many is 'good'? Probably twice whatever number you think may be adequate, if not more. (This is one instance where more is definitely better! I've never seen any instance where there were too many ground radials.) How long should they be? As long as possible/practical, which has nothing to do with convenience.
Why don't most people use radials instead of ground rods for grounding? Because there's a lot of work involved with radials, more than just pounding a rod or two into the ground.
It really does boil down to Ohm's law...
- 'Doc

And the 'catch' in all this is that there are never any guarantees.
 
W5LZ said:
It really does boil down to Ohm's law...
- 'Doc

And the 'catch' in all this is that there are never any guarantees.
Click to expand...

Times two on the no guarantee, Now if someone or anyone can convince the "Lightning" to follow ohm's law.

Lightning per say follows no rules and makes it's own decision where and when to strike.

All the grounding and prevention can be done correctly and precisely, yet a direct lightning strike will be catastrophic.

Having a residence in FL, lightning strike capitol, I have seen many times the antenna and tower take a strike, having that "good" earth ground does help to get the charge to ground potential.

The only antenna damage I have ever had was having a fishing pole ( imax 2000, antron 99 or something along those lines) sticking out a top of a tall pine tree with no ground wire going to an earth ground. I had two of those fishing poles blown apart by lightning strikes. Of course coax was not connected to any equipment or for that matter even inside a building.

Coax was laying on the ground. always used to think that the tap root on a pine tree was deep enough to provide a good ground, sure made that coax look like burnt spaghetti noodles.
 
Well, commercial broadcasting stations make it work all of the time. But it must be properly engineered.
Therein is the 'rub'.

Captain Kilowatt knows how it is done. True, getting the basic mechanical low resistance/high current flow part to ground is one aspect of the job. But getting it all to work right - like a commercial broadcast station managing to continue with broadcasts through multiple real-time lightning strikes - is the real deal.

Even if the mechanics of this kind of engineering was able to be done correctly by the amateur/Ham operator; I would be more than a bit leery to trust my equipment, home, and the lives around me for a 'first strike' test. Wouldn't you? Trial and error in this case is just a bit too risky.
 

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