When I hear thunder, or I'm temporarily away from my XP Home computer and
thunder is predicted, I turn the system and UPS off and unplug the modem
telephone line. Overkill? Before I did this I lost the built-in modem to a
nearby lightning strike (I assume).
However most businesses and many other systems are left on durng storms
evidently with no problems.
What do you do?
You know it's time to clean the refrigerator
when something closes the door from the inside.
I don't know for sure, but I *think* my cable provider (Verizon FIOS)
uses fiber optic lines.... which, AFIK, do not conduct electricity and
are therefore immune to lightning strikes.
So I don't do anything - unless it's one of those really-violent
thunderstorms and then I'll pull a few plugs until it passes.
Rightly or wrongly, my main concern is a strike to one of my TV antennas
propagating through the connected tuners into my LAN and/or taking out
I was responding to Mr Cresswell who said he believed he had fiber optic
cables and didn't think they conducted electricity. My point was that
during a rainstorm when the rubber or plastic covered cable was covered
with water, it was a conductor.
Remember: An armed man is a citizen. An unarmed man is a subject.
There still should not be a path to your equipment but most surges are
really induced transients anyway so that is not an issue.
If you start with a good grounding system and ground all of your surge
protection (on every wire that comes into the house) to a single point
in that grounding system, you eliminate virtually all of the surges.
Some point of use protection that combines protection of all
conductors at the equipment will do the rest.
It gets more complicated if you are dealing with a big campus and a
number of interconnected buildings but the concepts are the same.
lightning damage. Up on the top of a hill I had a ham radio repeater with a
120 foot tower in a building that was about 6 foot square. In about 30 years
one power supply burnt out a diode for the repeater during a storm. However
the part that went to a telephone line would go out every 2 or 3 years
before I pust a lot of differnet types of protection on it. Then I had to
replace the protection every 2 or 3 years. As there was a 300 foot tower
about 300 feet away from my tower, I think it helped protect from lightning.
If I had telephone lines I would unplug them. Having cable modem I don't do
anything. I do stay away from anything connected to the power lines or
telephone lines. Switch to a wireless laptop and telephone if I want to use
them. Equipment can be replaced,but people are difficult to replace or
If you are going to turn off the computer, unplug it. Off or on will
seldom make much difference.
Sofar I have been lucky. Seldom if ever have I unplugged anything except
the telephone line to the modem when I had dialup. Never lost anyting much
in the houses I have lived in from 1970. During a storm a transformer blew
out that fed a house I lived in. It did take out 2 surge strips and a built
in oven electronic control. The oven only burnt out a circuit board trace
and a MOV protector.
At the last house I lived in had a ham radio tower that was about 50 feet to
the top antenna and this house has one that is about 70 feet to the top.
Been lucky so far on that as I have not lost any radio equipment either.
On Friday, January 8, 2016 at 12:32:06 PM UTC-5, Ralph Mowery wrote:
When I was in the Coast Guard in Alaska, lighting hit the 1/4 mile high
LORAN tower. Since I was transmitter tech at the time, and spent most of
my days working in the transmitter building which was at the base of the
tower, I had the pleasure of repairing the damage to the transmitter that
was on-air at the time as well as the dummy load that the standby transmitter
was connected to.
The dummy load and final transformer assembly were housed in the same
cabinet for ease of switching between the 2 transmitters. When the
lightening blew up - and I mean BLEW UP - the final transformer assembly,
the shrapnel took out the dummy load resistor bank. What didn't get
pulverized melted in the resulting fire.
The worst thing that a LORAN transmitter technician can experience
is silence in the transmitter building. All stations have 2 transmitters,
which are swapped every 2 weeks - on-air/standby, back and forth. When
performing preventive maintenance on the standby transmitter, it is always
supposed to be available within one hour. (One *minute* of off-air time ruins
a "perfect month". "Perfect months", especially consecutive perfect months,
were the goal of any LORAN station. We received a ribbon for 7 consecutive
perfect months when I was stationed in Germany.)
Anyway, silence in the transmitter building means that your on-air transmitter
is down and that the standby isn't ready. It's a eerie, uncomfortable feeling.
We were silent for 4 days while we repaired the equipment. Our radio
transmissions didn't have the comforting tick-tick-tick of the LORAN signal
in the background, the scopes in the monitor room weren't glowing with
the signal's familiar envelope, etc. The only good part (OK, it's weird) is
that I had the opportunity to walk up to the tower and touch it. That is
not something that you can do when it's pumping out a mega-watt of signal.
We used to stand near the tower with 4' florescent tubes and have them
light up in our hands. You could hold one end of the tube with one hand
and slide the light up and down the tube with the other.
We made RF preheaters and one of the quick and dirty tests for the
shielding was waving a fluorescent tube taped to a broomstick around the
The cavity where the material was heated had holes drilled in a
hexagonal pattern both for ventilation and so you could look inside when
it was on. For illumination, there were standard 6" fluorescent tubes in
battery holders screwed to the aluminum walls. The fun part was watching
plant maintenance electricians who didn't know much about RF scratch
they heads while figuring out why the tubes lit without being connected
On Friday, January 8, 2016 at 9:38:35 PM UTC-5, rbowman wrote:
Another fun thing to do was to hold a safety meeting for the newbies on the
station and "explain" why they should never go into the transmitter building
without a transmitter tech.
We would bring one of the large oil filled capacitors and a hi-pot machine into
the mess hall and charge the cap up to 2 to 3K VDC. Then we'd turn off the
lights and use a dead man stick to short out the cap. The resulting Crack! and
spark was enough to scare the crap out of most of the newbies. After they
calmed down we let them know that the transmitters ran on voltages that were
about 8 times what we had just used. "Stay out of the T-building unless one of us
is with you."
One time we got a little carried away. We charged the cap up just a little too much
and when I shorted it out it blew the threaded metal rod out of the wooden handle
and broke the braided grounding strap. The rod and strap went clanging across
the tile floor and I almost crapped my pants like a newbie! It was pretty impressive.
When I was using POTS modems, I noticed the modem was damaged by
electrical transients much more often that anything else. That's one
reason for preferring an external modem. It's more separated from the
rest of the PC.
If it is close, I shut it down. Couple of years ago there was a
lightning strike near me. It entered by a light fixture on the detached
garage and took out a receptacle, circuit breaker, TV, receiver, doorbell.
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