The telco has overhead wires everywhere in town connected to
a $multi-million switching computer. So the telco must be
down for about 1 week every year replacing their computer?
Not likely. Direct strikes are easily earthed without damage.
If that 12 AWG (typically used for 20 amp service) was
carrying 50,000 amps continuous, then that wire would be
vaporized. Well that wire can carry up to 300 amps
continuous. Note the word 'continuous'. That wire can carry
hundreds of thousands of amps IF the current is very short.
Notice how current capacity changes when we change the
period. What is the typical lightning strike? Most are less
than 20,000 amps. And these transients are so short
(microseconds) as to not damage that 12 AWG wire.
How many amps can a 24 AWG wire carry? Well that MOV with
24 AWG wire leads is rated to carry something on the order of
5,000 amps. Furthermore, the wire is not vaporized by those
5,000 amps. The attached MOV (not its wire leads) fail if
current significantly exceed 5,000 amps. 5,000+ amps on a 24
AWG wire? Not a problem because we add an additional fact -
time of the 5,000+ amps. Time is so short that those leads
easily handle a quick 5000+ amps.
Also incorrect (a product of the urban myth machine) is that
lightning rods discharge the air. Somehow a lightning rod
will discharge "the positive earth charges into the
surrounding atmosphere"? One small problem. Charges that
create lightning are located miles away in the cloud and often
miles away elsewhere on the earth. Lightning is electricity -
not electrostatic charges. Lightning connects charges in that
cloud to other, distant, and earth borne charges. Tell us
that a lightning rod will somehow discharge a cloud that is
miles away? This is the myth promoted by ESE industry.
Early Streamer Emission industry claim their devices
discharge the atmosphere. But ESE manufacturers never provide
science reason nor experimental evidence for their myths.
Myths? Without both theory and experimental evidence, then a
fact does not exist. The ESE industry provides neither.
The ESE industry tried to create NFPA 781 standard. When
rejected, they attempted to get the well respected NFPA 780
standard eliminated. The ESE industry were even accused of
blackmail - sue the non-profit NFPA into bankruptcy - to get
their scam product approved.
How foolish is this idea that lightning rods discharge the
atmosphere?
http://www.nfpa.org/assets/files/PDF/700Minutes.pdf
(see PDF page 18+) 00-60 D#00-22 starting with mention of
Heary Brothers Lightning Protection Company, Inc., Bryan
Panel Report follows:
The proponents of that technology, primarily those associated
with the Heary Brothers Lightning Protection Company, Inc., ...
have extolled the technology and, in particular, have claimed
that ESE terminals offer a vastly increased zone of protection
over that of traditional lightning rods. Those claims have been
disputed and, most recently, a special panel created to
consider information and to issue a report concerning ESE
lightning protection technology to the Standards Council (Bryan
Panel Report), firmly rebutted the claims of ESE proponents that
the technology had been adequately validated, concluding, among
other things, as follows:
The ESE lightning protection technology as currently developed
in the installation of complete systems does not appear to be
scientifically and technically sound in relation to the claimed
areas of protection or the essentials of the grounding system
There is a fundamental problem with HeyBub's post. It is
based on speculation; not based on science concepts,
experimental evidence, or even a responsible citation. You
have a choice. Either believe the NFPA (authors of the
National Electrical Code) or believe HeyBub.
HeyBub wrote:
Lots of replies imply that grounding will handle a lightning strike,
especially mentioned is grounding the satellite dish.
You need to understand that grounding a dish, or almost anything
else, does nothing to mitigate a lightning strike. If you're
struck, you're toast. No piddly #12 wire is going to handle 50,000
amps at (up to) millions of volts.
What these ground rods do - also lightning rods - is act as a
preventative to lightning by discharging the positive earth
charges into the surrounding atmosphere - an invisible shield
around the device - satellite dish or lightning rod. This
shield, however, can be penetrated by a sufficiently
large lighting bolt.
...