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question on grounding antenna

post #1 of 7
Thread Starter 
Hi,

I currently have a DB2 in the attic, but want to move it to the roof to pick up a few more channels. I have read quite a bit on grounding, but still have questions as you get different information on different sites.

my understanding of how to ground:
1)run 8gauge grnd wire from antenna mast to ground. Use as straight a wire as possible.

2) use grounding block where coax enters the house. Run 8gauge from this block to the ground.

here is where i need help. Some say you can buy a ground rod...hammer in ~8ft into ground and just use this for both ground wires (steps 1/2 above). Other sites say if you put in a new ground rod you must also tie it into your existing ground rod (where your electric panel, etc connect).

In my case where I want to put the antenna is on the opposite end of the house from my electric panel/existing ground rod. I would have to run wire all across the house...

can I put in a new ground rod and not tie it into existing?


thanks for any help/advise.


chuga
post #2 of 7
Quote:
Originally Posted by chuga View Post

can I put in a new ground rod and not tie it into existing?

Not if you want a safe system...
post #3 of 7
Best practice (and to meet code) is to bond the two grounds.
post #4 of 7
1) Lightning.
From everything I have read, here is my understanding. Most lightning is a negative strike with positive tendrils extending from points above the surface first. The purpose of bonding all your grounds with a bare wire, as close to the earth as possible without being damaged with a weed trimmer, will be apparent. If your home is to be hit with a direct negative lightening strike it will appear as one unified ground on the outer skin of your residence. The positive tendrils start to rise, touch your ground around the building, extend up the antenna to complete a circuit with the negative cloud charge. BANG! Your ground wire disapears under millions of volts. Every piece of electronics in your home is fried. Hopefully you aren't near plumbing or a wired phone. But that blown away ground has created an ionized path OUTSIDE for the current to follow, and your house may not catch fire. Near strikes are less severe and positive strikes are much worse.
Next post or edit, why to bond attic antenna to ground and ground loops related to bad neutral bonds.
post #5 of 7
Quote:
Originally Posted by chuga View Post

... if you put in a new ground rod you must also tie it into your existing ground rod (where your electric panel, etc connect)...

This is correct. It is called "bonding" the grounds, and it is important to prevent a voltage difference (aka ground loop) between the two ground sources which can damage electronics. It should be done, even if you have to run ground wire from one end of the house to the other.

The purpose of grounding the antenna (other than meeting code) is to keep static charges from building up on the antenna when wind blows across it. This may protect electronic equipment and reduce the attractiveness of the antenna as a lightning target. It will not protect your equipment against a direct lightning strike.
post #6 of 7
Thread Starter 
thanks for the replies

Now I wonder if I should just run the antenna/coax grounds all the way across the house to my grounding rod...rather than put in a new ground rod and have to bond it to the existing rod.

any reason to put in new rod and bond to existing versus running longer ground wire to existing ground?


thanks,

chuga
post #7 of 7
Quote:


any reason to put in new rod and bond to existing versus running longer ground wire to existing ground?

Yes. For better lightning protection, it's preferable to have a local ground rod as close to the mast as possible. But if that rod is not the home's main power ground, it must be bonded to the power ground to prevent possibly damaging ground loops from occuring.
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