Grounding TV Antenna

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Old 08-06-08, 08:35 PM
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Grounding TV Antenna

I recently read an old post on a NEC forum that stated that a separate ground rod for a TV antenna must be bonded to the house ground. For over 40 years, my chimney mounted antenna has been grounded to a separate ground rod. It is not practical for me to move my antenna or to bond my ground rod to the house ground. I have three questions:

1. Isn't ground ground?

2. Why does NEC require that a separate ground rod be bonded to the house ground?

3. Does a separate unbonded ground rod work?
 
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Old 08-06-08, 08:48 PM
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A separate ground rod, properly installed would work. The reason for the bonding requirement is that in the event of a lightning strike extreme potentials exist and ground at point A and ground at point B could be thousands of volts or more different even if those points are just feet away from each other.

This causes an effect called flashover. It is best to bond all grounds together if possible and the more grounds you can make the better. This is really true if you do not have a public water system with metal pipe to the house.

I am an amateur radio operator and have lots of antennas. I have private well and plastic pipe to the house. When replacing this plastic pipe many years ago I ran very heavy copper cable to the well head and bonded it there. I also have multiple grounds (rods) at the base of my tower as well as a ground rods for the electrical system. All these grounds are bonded together. Ground conductivity in my area is generally good. In areas where it is not more grounds spaced over a larger area and bonded together may be needed.

I am not sure where this antenna ground is in relation to your service entrance, where the ground for it would be but you could run a wire buried just below the surface between the two.
 
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Old 08-08-08, 08:22 PM
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Thanks DSC3570 for your reply. My antenna, chimney, living room and TV set are located on one side of my ranch type house and the service entrance is about 100 feet away on the opposite side of the house. My ground rod is an eight foot bronze grounding rod driven into the ground to within one foot of the end. The clamp is a standard ground rod clamp.
 
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Old 08-08-08, 09:47 PM
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Ground rods should have all 8 foot in contact with the ground. Your rod should be bonded to the house ground and in full contact with dirt, not just the 7 foot in the ground that you have.
 
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Old 08-09-08, 08:51 AM
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Grounding is an art in itself. Here is an interesting paper on effective grounding.

http://www.cpccorp.com/deep.htm

In many parts of the country if your only means of ground is a single ground rod sunk to 8' it is not a good ground.
 
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