Surge suppressors that use the AC wall outlet for ground are essentially
useless against nearby lightning strikes since the distance and relatively
small diameter wire conductor (16/18ga) to the main power panel earth ground
rod looks like infinite resistance to a large current surge. Relatively
smaller spikes on the AC line caused by appliance motors etc... can be
shunted, but not a huge current induced by a nearby lightning strike.

There is much good technical information at Polyphasor's web site which will
keep you busy with your research for some time.

"Dr. Artaud" wrote in message
. 97.142...
We had a rather bad storm the other day, lightning striking everywhere.
As I left work, it hadn't started in that area yet, but I could see it
off in the distance. I phoned my son to ask if he could disconnect the
long wire antenna from my Yaesu FRG-100, but he said that the area very
near my house already had a couple of bad lightning strikes. I told him
to stay away from the radio.

When I got home, most of the storm had abated, though as I traveled home
I could see massive lightning strikes occurring in areas around me. The
storm was accompanied by tremendous downpours, and flash flooding
warnings were issued.

The National Weather Service (NWS) screwed up on this one, they didn't
even issue the warning until after the storm had wreaked its havoc. Nice
work guys, Helen Keller could have done a better job.

I get home, assess the trees in the yard, everything looks normal.
Problem is that there is no power to the neighborhood, a condition that
remains unchanged for the next 1 ½ hours. No problem, I can use my
handhelds and portable shortwave radios.

My wife arrives home, and as she is walking through the yard, she talks
to the neighbor. The neighbor explains that the "wire antenna" in the
yard was struck by lightning. I go out into the yard to examine the
antenna and find it lying on the ground. I'm convinced that very high
winds somehow pulled the antenna down. I picked it up and examined it,
and lo and behold, some of the insulation is melted off. As I just
installed an arrestor of sorts (it's an old one that I bought on EBay, it
appears unused, a ceramic block with 3 terminals, 2 outer ones for the
antenna wire, and a center one for the grounding wire) about 3 weeks ago,
having had the antenna for a couple of years without it.

The melted insulation extended to the arrestor, and the wire after the
arrestor was normal in appearance. I examined the Yaesu, it appeared
normal, but there was no power in the house yet, so I couldn't tell if
operated ok. Being impatient by nature, I got the correct power cord,
took the radio to the car, opened the car hood, and connected directly to
the battery. The radio powered up, but didn't receive. It looked like it
wanted to receive, when tuning through the frequencies every once in
awhile I could hear a local station pounding through, overloading the
radio, but even with a makeshift antenna I could not receive anything
willfully on shortwave or broadcast AM.

I gave it up as toast, and I called AES in Cleveland, explaining that it
was lightning damaged. They said that I could sent it back, but that they
would in turn send it to Yaesu for a proper assessment. He explained that
Yaesu would try this and that, and probably end up saying that it was
irreparable.

Eventually the power came back on, so I took the radio and began to
experiment with it yet again. When I tried it at the car, I used both
antenna inputs, but I had forgotten to throw the switch on the back to
use the low input impedance connector, so I tried the radio again after
throwing the switch, placing the antenna wire in the Low Z connector,
turned the radio on, and viola, the radio worked. But why doesn't the
High Z terminal work. Since the radio had been exposed to such a large
transient, I decided to disassemble it to make sure that nothing else is
wrong. When I began to remove the screws to open the case, I noticed that
the side was discolored. I didn't remember seeing that before. Oh well, I
continued with my screw removal. When I removed the top of the radio, I
noticed a small point below the discolored area on the inner unpainted
chassis that was about the size of a capital O. With the top off, I could
not really see anything wrong with the radio, but was curious why the
High Z terminals didn't work. I consulted a schematic, and the only
difference between the inputs were the switch and a choke or inductor. I
could see the inductor, it appeared normal.

I decided to remove the circuit board and had to pull about 10 wire
connectors of various sizes from the board. This is a struggle, as there
wasn't always an easy way to start to pull the connector from its socket
by using a screw driver to twist and pop the connector out of its locked
position. I persevered and finally removed all the wires without damage.
I removed the screws securing the board, the antenna connectors, and the
power connector. Viola, I removed the board.

Surprise, a large blacked area was found just under the High Z antenna
terminal connection to the circuit board. Mostly soot, but some minor
damage to the chassis metal was observed as well. I examined the bottom
of the board and found that a ¼ trace that carries the High Z antenna
signal to the inductor was neatly vaporized. The board was in excellent
condition. The area that the trace occupied was unblemished, just the
trace itself was gone. I cleaned the inside of the radio and the circuit
board, soldered a wire to replace the trace, and reassembled the radio.
Viola, the High Z terminal worked.

The voltage path and its destruction seems to be as follows. The
lightning strike was largely shunted to ground by the arrestor, but a
surge continued on into the radio. Entering the radio, it jumped to the
chassis just under the connector, the surge exited the radio on the side
near the front panel close to the headphone jack. It jumped to my metal
cased DVD player that was so close to the radio that it just about
touched it, ruining that, somehow killed the clock radio that sat atop
the DVD player, altered the TV nearby, which still works by no longer
works by remote control. The surge entered the power system, and on
another floor of the house, killed my cable modem, my wireless router,
tripped the circuit breaker that fed the modem and router, blew 2 light
bulbs in the house, and tripped 2 GFI receptacles.

Questions:

1. The router and cable modem were on a different circuit from the power
for the radio and DVD player. The Radio, the DVD player, and the clock
radio were plugged into a spike suppressor strip. My house itself has
whole house spike suppression at the power meter. I took the spike
suppression strip apart to examine for damage, none was visible. If the
surge entered the power system, making it to the lighting panel, why
wasn't it shunted to ground by the power strip and the whole house
suppression which was only about 3 feet from the panel?

2. Could it have been electromagnetic forces that destroyed the cable
modem and router?

3. My equipment was not grounded or bonded. Surprisingly, the items that
were destroyed near my Yaesu were items that had internal power supplies,
so that a direct connection to the neutral was available. The items that
were powered by transformers, including the Yaesu itself, were
unaffected. I have a Uniden metal case scanner atop my Yaesu that was
plugged in, and off with a mechanical switch (part of the volume
control), this radio was unaffected. I also have a speaker system for my
DVD and TV in the bedroom, this was also off by a mechanical switch and
is transformer fed, this was also unaffected. Though the Cable Modem and
Router, as described above, were always on, so is a great deal of other
equipment in the house, including my main TV, DVD Player, AV Receiver,
and so on. Why the preference for some equipment and not the other?

4. Lastly, how can I have an outdoor antenna and survive a strike without
damaging equipment? I know that I should disconnect the wire when before
a storm, which I always do, but this day was not supposed to have storms,
and I couldn't get to the radio in time. Was the wire more likely to be
struck since it had been grounded? Unfortunately, the strike came down my
tree in the backyard, obliterating a limb at the top, (a very tall tree),
and traveling down the outside, casting off bark as it traveled. The line
in the bark comes right to the end of my wire antenna and no lower. Could
a "leader" have been initiated by the antenna grounding system that
actually led to the strike? The antenna itself was several feet from the
tree, tied to the tree trunk with a rubber tube. If the wire had
previously been removed from the radio and simply tossed onto the floor,
what may have happened with the surge?

Thanks for your comments, and be safe when lightning becomes an issue.

Dr. Artaud