Grounding antenna

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fredg

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First let me attempt to describe what I have....

I have a few 2" poles connected together to form my mast. The end of the mast sits right on the ground (buried a few inches). I have a 2 foot 2x4 extending out from under the roof eaves of my house and clamped to the mast. No guy wires.

The total height of the mast is maybe 25 feet from ground to top. I have a simple dual band ground plane antenna attached to the top of the mast.

I have had this antenna up for over 15 years in Kansas storms with lighting and crazy wind.

Never had an issue. The antenna has never been grounded.

Recently I got a bug about house fires from a lighting strike so I got to thinking maybe it's time I ground the antenna.

I did a bunch of online reading and found one instance where a guy had an antenna up for 30 years not grounded and never had an issue, the antenna was replaced with a new one and grounded, a week later a lighting strike hit the antenna and burned down his house.

I read all about having to bond all the ground rods on the property. Is this really necessary for a simple receive antenna? The electric meter ground is over 100 feet away around the house. I could see the need to bond them if I was hooking up an outside air conditioner unit or some such thing that is pulling power.

So.... do i leave well enough alone or do I run a ground rod in the ground and ground the mast?

EDIT: I should also note that I have no concern for the scanner equipment getting fried, my ONLY concern is my house burning down.
 
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fredg

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Well after reading a bunch more I have decided to go ahead and ground it. Here's a weird thing... I mentioned that you are supposed to bond the ground rods together, but I do not have a ground wire or rod coming from/going to my electric meter... ????
 

12dbsinad

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Grounding any type of antenna is a good idea. It will certainly never hurt anyting, that's for sure. The more grounding the better. If you look at an average cell tower site, you would be blown away at the grounding. Granted, these are alot higher than 25', but everything is bonded together, inside and out with a large ground ring of rods. Your electical panel should have a ground rod. The wire will connect at the inside of the breaker panel (bonding ground) / meter enclosure and out to a ground rod. A number 6 wire for a 100 amp service and a number 4 wire for a 200 amp service.
 

jcop225

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If you have AC power in your house(I'm making the grand assumption that you do), there is an ground rod for the power system, it's probably near the main electrical panel. It's not essential that you bond the two rods together, just don't ground any electrical equipment to your 'antenna' ground point.

If all of your masts are metal and physically connected metal to metal and the bottom of your mast is buried in the ground, then your system is essentially grounded. A deeper or multiple ground points couldn't hurt but scrape any paint or finish off the bottom of the mast and you should be set.

A direct strike will cause damage regardless of the ground system, but this will send most of the energy into the earth and protect against damage from a proximity strike.
 

3bamams

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yes ground your antenna

I love this topic and have researched it for many years now and have come to find out that it’s all or nothing when it comes to lightning grounding. Of course something is better than nothing but in your case grounding should be easy because your mast is buried directly into the ground vs on the roof top which requires extra attention. I would use plastic or some sort of rubber as an insulator and not wood like you have done under the eaves because wood can hold moisture and moisture conducts electricity.

It would not hurt to have an air terminal mounted on the highest point of the mast with the air terminal extending above the highest point of the antenna. I have over $200 dollars into just grounding of the antenna and coax cable for just a receiving antenna. I do this not only for direct lighting strikes but for insurance reasons and for indirect lighting surges which in the past has charged and arced my coax cable inside the shack when it was not grounded at all. I could go on and on but I would ground your antenna and plan on putting money into just that to do it the right way.
 

WA0CBW

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I would suggest you take a look at the NEC (National Electrical Code) section 800, 810, and 820 to see what is required for amateur radio antennas, coax entering your house, and connecting all external ground rods to the main electrical ground. As was mentioned above, grounding is an all or none kind of thing. Most lightning damage is caused by flash-over from one piece of equipment to another because of a difference of potential. That is the reason for bonding all equipment to a single point ground. The other is to equalize the charge between the ground and the sky. That is the reason for grounding the mast that supports the antenna and using DC grounded antennas. All of these measures will help to reduce the chance of taking a direct lightning strike. All of these grounding measures will not mitigate the damage caused by a direct strike but are designed to reduce the chances of getting a direct strike. A lightning strike that has traveled several thousands of feet is not going to be deterred by disconnecting the antenna and moving it a few feet away from your radio.
BB
 

fredg

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Thanks for the info guys! I cannot find where the electrical panel is grounded, there is nothing on the outside of the house. My guess is that runs through the wall to the cement slab, maybe there is a ground rod in the cement slab. Either way it is not something I can get to.

I will use the 8 foot ground rod and also the suggestion of insulating the mast from the wood as I was thinking the same thing about the wood absorbing water and becoming conductive.
 

cpetraglia

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Gronding

FYI
My house is 50 years old and only had a #8 wire going to the main copper waterline coming in. No ground rods. Of course, when I up-graded to a 200A service I had to install double rods to satisfy the inspector.
Trust me, you have a ground somewhere.

Chuck
 
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