Hi Gary,

I did everything right except I forgot about one old abandoned rotor
cable that was coiled up behind 4 file cabinets, out of sight out of
mind. Luck of the Irish, the day I took the hit, I had sparks flying
all over my shack. My pooch who was young then, terrified of thunder,
came to my office to be by me for protection, just when the sparks
began to fly. He never came into my office ever again!
The only damage from this rotor wire was a few burn marks on the back
of the file cabinets. The tower obviously took the main hit.

A friend in Mobile, AL had several station equipments damaged this summer
when protection was presumed to be "complete". Old cabling on the floor
behind equipment racks was inductively charged and arced over to the
equipment and computers, defeating the extensive surge protection installed.
I had considered this a serious enugh problem to include it in a warning on
my web page, and he was of course furious with himself about this since we
had previously talked about it. This is also what I mean by the statement
that lightning finds and exploits the weak parts of a system.

As an aside. A tree outside my mothers home was struck by lighting.
Split that sucker almost all the way to the ground. Dad bolted it
back together with threaded rods and it survived, it's still living
too.
But the reason I brought it up is that INSIDE the house, sparks danced
all over my mothers stainless steel kitchen sink, made burn marks and
pits all over it. We later discovered the aerator on her faucet spout
was fused to the spout and it too was severely burned and pitted.

Back then all the waste lines to the sink were metal, not PVC as used
today and all the water lines are copper. So I assume both the sink
and the faucet were grounded.

Makes one wonder how lightning got inside the house and bounced around
in her sink and did enough damage that the sink and faucet had to be
replaced.

Could be either from an older home's cold water pipe grounding, or EMI from
the nearby strike. The former is more likely, when ground becomes saturated
with HV from a nearby strike, it raises the potential of everything
connected to it. Nowadays this is called "GPR" or Ground Potental Rise.
Possibly one of the biggest causes of damage to stations that are otherwise
"protected".


TTUL
Gary


Cheers,

Jack

Hi Jack

That was probably the cause!

I figured the sink itself was at one ground potential and the faucet
at another which caused the arcing.

Of course, the way mom described it, one would think the whole sink
was ablaze.
Even back then I thought of possibly a single drop of hot metal
(probably from the aerator) and how that is what probably bounced
around in the sink sparking all over the place. Like dropped hot
metal when your welding goes all over the place.

Speaking of differing ground potentials. I think the wierdest thing I
ever saw was when my step-son was taking me through the automated
welding section of a body assembly plant for cars.

A line of steel platforms bolted to a steel floor framework, between
two of the platforms (about 2 to 3 inches apart) there was an
occasional arc that occurred when the machines on each both stopped at
the same time.

Don't know if you remember the old vacuum powered windshield wipers
that operated independent of each other. Every once in awhile they
would be in sync for a few wipes.
When these welders came into sync they hummed really loud and when the
sync broke is when the arc would jump between their two stands.

I thought it was interesting!

TTUL
Gary