Love it when people are so knowledgeable that they only need
make a declaration, never need provide any numbers, never
provide examples, demonstrate no grasp of technical facts, and
insist they should be believed blindly. Only they can be
trusted to know.
Your telco's $multi-million switching computer connects to
overhead wires everything in town. Since nothing can protect
from lightning, then one week every year, you are without
phone service when the lightning damaged computer is
replaced. Those cell phone towers stop providing service for
a week to replace destroyed equipment. Commercial FM and TV
stations atop the Empire State Building are out of service for
26 weeks every year due to the 26 direct lightning strikes
every year. No wonder those communication and equipment
manufacturers are so profitable.
When was Pop going to reconcile these examples with his
knowledge? Or are we to believe only he knows what is right?
Pop never provides any supporting theory, numbers, or
technical citation with his claim. He just knows.
It is routine to earth lightning before it gets inside the
building; no damage. If nothing can protect from lightning,
then why install any surge protector? What else overwhelms
protection already inside appliances if not lightning?
Appliances already have internally any protection that is
effective on the power cord. Protection that assumes the
seriously destructive transient such as lightning will be
earthed before it can enter the building. Computers are some
of the most robust appliances. For example, look at a
computer grade UPS output when in battery backup mode. 120
volts on this one is really two 200 volt square waves with up
to a 270 volt spike between those square waves. This output
can even damage some small electric motors. But this output
is perfectly fine for computers because computer power
supplies are (as required by Intel specs) so robust.
But even computer internal protection can be overwhelmed it
destructive lightning is permitted to find earth ground,
destructively, via that computer. Even the robust computer
needs lightning to be earthed before it can enter the
building. This is called 'whole house' protection - on every
incoming utility wire.
Whole house protection is not standard in most homes. If
the homeowner does not specifically request it during new
construction (only in the past few years) OR has not has it
installed, then 'whole house' protection does not exist.
Furthermore, if the building's earthing system is not to a
single point - is not properly installed - then the 'whole
house' protector is still ineffective.
We earth every incoming utility, either via a 'whole house'
protector or via a dedicated ground wire, to the single point
ground. That is for lightning protection - so that lightning
will not overwhelm protection already inside all appliances.
IOW we first learn what was well proven and well understood
more than 60 years ago. Back then, the only buildings with
electronics to protect were telephone switching centers,
commercial broadcasters, communication towers, etc. Today
every building has transistors - requires properly earthed
protection especially from lightning. Its called learning
from those who proved the science before declaring nothing can
protect from lightning. It is routine to suffer direct
lightning strikes to incoming utility wires and not suffer
damage. The technology was that well proven for too many
Unfortunately most homes still don't have protection
sufficient for transistor appliances. Using protectors that
cost about $1 per protected appliance.
Protection from lightning comes in at least two flavors. One is the
physical damage including fire from a direct strike. For that see your
local lightning rod company. That is not a do it yourself job.
As for wiring, I suggest that you start by replacing the GFI, they may
have given their all in the effort. As Joe noted, make sure your home
grounds are are properly designed installed and have not been damaged.
Note: a lightning strike can damage wiring so that it could cause a fire or
other problems later. I would contact my insurance company and they may
suggest and supply or pay for a professional inspection and repair.
I would suggest adding whole house surge protection. I have it on my
home. If you feel comfortable with replacing or adding a circuit breaker,
you may be ready to DIY. However if opening up the circuit breaker box
makes you a little uneasy and you don't know what you are looking at in
there, I suggest having them installed professionally.
As for personal experience; I had a lightning strike about 18" away from
my A/C compressor unit. It blew out part of the controller circuit board,
but did no damage in the house. I was able to re-wire the board eliminating
the damaged section as that function was duplicated by my thermostat.
Joe put his finger on the most common problem. Be sure you have a good
grounding elerctrode system and that EVERYTHING is bonded to that
system, preferably to a single point. Most "surge" damage is actually
a transient voltage that is reconciling a grounding difference between
isoilated electrodes through your equipment. Once you have a good
single point grounding system, be sure all of your protectors connect
there (cable, phone, satellite and power)
The second layer of protection is a panel mounted protector, along
with protection on the other inputs grounded to the system and the
final layer is point of use protectors that incorporate all the inputs
to a piece of equipment.
It doesn't hurt to clip ferrite beads to the signal cables to attack
the leading edge of common mode transients.
We developed this strategy in SW Flortida for computer systems that
never get turned off and we were quite successful, in spite of almost
daily thunderstorms for most of the year.
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.
So, then, get a lighting rod up (or more than one) and individually protect
each critical device plugged into the mains.
If you live in a mobile home, nothing helps. Mobile homes attract tornados,
lighting, and stray dogs.
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
(see PDF page 18+) 00-60 D#00-22 starting with mention of
Heary Brothers Lightning Protection Company, Inc., Bryan
Panel Report follows:
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.
I'm going to install an outdoor TV antenna, but am confused about how
to ground it. Its mast will be 12' above the ground and about 25' over
from the house's breaker box ground rod.
Should I use stranded wire instead of solid?
Should I install a ground rod into the dirt directly below the mast, or
can I simply run a #4 ground wire from the mast to the breaker box
Is there ever any harm in installing a second ground rod, provided it's
bonded to the main one?
Volts500 provided a complete description of grounding a
house. I believe this in the newsgroup alt.home.repair
entitled "Grounding Rod Info" on 12 July 2003 also included
how to earth the TV antenna per code requirements at:
Meanwhile, a larger number of ground rods tied together will
usually improve the building earthing system. The code
provides a rather subjective number that may require a second
ground rod. Many electricians don't even bother to measure.
Since the second earthing rod will improve conductivity, they
just install the second rod automatically.
larry moe 'n curly wrote:
Direct strike? Have you an experience? I was an EIC at a BIG computer
systems installation located in a basement of a 7 story building at a
university campus. One day we took a direct hit. It knocked off all the
substation main breakers(one we have to engage winding up big springs).
Garbled data on the mass storage subsystem comprising of ~150 or so hard
drives. Now what did you say?
You know, occasionally I see this happen here too. And I've yet to
hear an explanation from anybody about how this happens. I'm just
curious, as I'm sure others are. Like does it pop up again on some
particular newsreader, etc?
Either that, or they are replying through a 'forum' on some web page.
Lotsa web sites mirror various Usenet tech groups, to make themselves
look more active than they really are. Some of them string-search
subjects, and only mirror stuff that looks on-topic for their narrow
site. The mirrored posts never get expired. Not all of them are ethical
about marking themselves as a web portal on the replies people make.
Google your own name some time- your posts will show up on web pages you
have never even heard of. Too bad we can't charge those webmasters for
our learned words.
He said direct strikes are easily earthed without damage.
Lightning hit my one-story house. It blew masonry a hundred feet,
knocked a hole in the roof, and knocked off siding. It zapped a lot of
electronic stuff, including two stereo receivers ten feet from me.
Neither was connected to an antenna. One was plugged in but not on.
The other wasn't even plugged in.
I was online at the time. My monitor sat blank with blotches of
various colors. Cycling it off and on degaussed it. My computer
restarted and I found no damage, not even disk corruption. My cordless
phone was fine, too.
Across the street, the strike on my house wiped out everything my
neighbor had connected to his phone line: computer, satellite receiver,
and cordless phone set. For years, he had ignored my advice for simple,
cheap grounding to protect him from lightning damage.
Many years ago there was a lightning rod salesman who sold
mainly to rural customers. He stopped at a farm and was
greeted by a woman who said she didn't want a lightning rod,
didn't need a lightning rod, and wasn't the least bit
worried about lightning. But, she was afraid of thunder.
At that, the salesman said "You're in luck. I just happen to
have a thunder rod in my car!"
He then went to the trunk of his car and pulled out a
charred, blackened lightning rod he'd replaced for a
customer after lightning struck it.
"Here you are, ma'am, the finest thunder rod available
anywhere. I can have it installed for you today!"
The woman bought it, and was so relieved she'd found a
thunder rod that she began telling her friends about it, and
how she wasn't afraid of thunder any more. They, feeling
sorry for her, told the county Sheriff, who quickly tracked
down the salesman, forced him to take the thunder rod down,
and refund the woman's money.
But from that day forward, the woman was once again a
nervous wreck every time there was a storm, and cursed out
her friends for helping her.
Polyphaser is an industry benchmark. Their application
notes are considered legendary among industry professionals.
Polyphaser also discusses "discharging the positive earth
charges into the surrounding atmosphere":
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