antenna grounding

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ppremc

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I am installing a new antenna and mast for my pro 197. I have a whole house arrester and I am planning on driving an 8 ft. ground rod.
with this setup is it a must to bond with house ground if accessibility is a problem? Thanks to everyone in advance.The antenna is mounted on the eave of the house about 35 ft. high.
 

n5ims

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I am installing a new antenna and mast for my pro 197. I have a whole house arrester and I am planning on driving an 8 ft. ground rod.
with this setup is it a must to bond with house ground if accessibility is a problem? Thanks to everyone in advance.The antenna is mounted on the eave of the house about 35 ft. high.

While it isn't "a must" to bond the antenna's ground to the house ground, doing so will help to minimize the damage when a lightning strike happens. I can't stress enough that grounding should be done correctly (as described here often) to reduce or prevent damage and to prevent your insurance claim for any damage from being nullified due to improper grounding.

In simple terms, what happens when the grounds aren't bound properly is that the current from the lightning is directed to the ground at the antenna's ground (say a million volts at thousands of amps) and then flows through the ground to the house ground (reduced to say hundreds of thousands of volts and hundreds of amps) where it then flows into the house and burns up everything electronic (and possibly what's simply flammable). This result is pretty much the same if the strike is to your antenna or comes in through the electric lines.

While it may appear that tying the two grounds together would cause the lightning strike to have a direct path into your house, this isn't what happens. The damage is often caused by the difference in potential between the two grounds. Connecting them together causes this potential to be zero (or nearly so).

While there is much more going on in a lightning strike (either direct or as is more often the case a near miss), a complete explaination would require much more than this simple explaination. Basically the best advice is to ground the antenna properly and bond all grounds together.
 
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Bote

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Because of the incredibly high rise times in the currents induced by lightning, a round wire becomes an inductor with high impedance, which reduces its effectiveness at drawing away the lightning's energy.

If you really want a decent buried ground system, bury flat copper strips or flashing in the ground in a starfish arrangement about 10 foot radius. Bond these to several ground rods driven into the ground at the apex in the center. This gives you a lot more conductive surface in contact with the Earth and greatly reduces the inductive reactance during a lightning strike.

Running copper strips around all four walls of your radio shack as an internal ground system and then bonding that to the external ground system is left as an exercise to the reader.

There's more to it than htis, but it's a good start in the lightning capital of the U.S., a.k.a. Florida.
 

James04TJ

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I would say that it is essential to bond all of your grounds together (and so does the National Electrical Code, Motorola, and M/A-COM). Your whole house surge arrestor will do nothing to protect your antenna feedlines.

Motorola's R-56 manual is considered the bible for equipment installation to include site grounding but M/A-COM produces a nice compact version with their site grounding standards. I highly recommend spending some time reading it and working to install to these standards: http://www.repeater-builder.com/ge/lbi-library/t4618r3a.pdf
 
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