[TowerTalk] RE: Grounding, Lightning & corona discharge

[Bill Fuqua <wlfuqu00@uky.edu>]

I have some questions, with some answers of my of my own.

1.  Where does the charge come from that is being dissipated by the spiderball?
    Answer: From an induced charge on the ground that is balanced by the 
charge in a near by clouds.

2.  How is the discharge produced?
    Answer:  By what is known as field ionization which requires a very 
high field at the tips of the Spiderball's needles.

3. Where do the ions or free electrons that are produced by the corona 
discharge go?
    Answer: They can not go to ground because ground is at the same 
polarity and they can't just dissipate in the air due to the fact that all 
atoms in the air are neutral and if they did take on a charge they would 
become ions themselves. They spread out and are attracted the opposite 
polarity charge source (the cloud). The ions and free electrons produce the 
conductive path for current to flow just as in a neon light. They may 
produce a large cloud of charged particles around the tower effectively 
making it a much bigger target than before.  If a number of cosmic ray 
tracks cross and produce an ionized trail thru the cloud of charged 
particles around your tower, guess where the lighting will go. It will take 
the more conductive path to your Siderball thru the ionization cloud around 
it .
73
Bill wa4lav

4. Why do cell tower owners use spiderballs?
    Answer: They are just as effective as a lightning rod. So it will not 
hurt if used in place of a lightning rod unless you believe that they do 
work and don't take the other lightning protection precautions.

5. These devices are "Snake Oil" just like the cell phone antennas 
enhancers  that you put in the battery compartments of the cell phones.

A lot of people buy into the spiderball myth after seeing a little 
demonstration using a small toy VanDerGraff generator.
By adding the spider ball to the dome on the top of the generator they 
demonstrate the corona and show that it will not produce a large spark as 
before.  However, all the salesman is doing is discharging the dome which 
is insulated from the base of the VanDerGraff and the charge particles then 
go to ground. This also reduces the potential (voltage) of the dome of the 
VadDerGraff generator and reduces its ability to produce a large spark.   A 
real test would be to ground the spiderball and think of the dome of the 
VanDerGraff as Thunderstorm cloud which is isolated from ground and has 
a  large electrical charge and large potential above ground. Then you will 
still get your sparks and right to the spiderball.

73
Bill wa4lav
 

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