On Thu, 21 Aug 2008 13:00:35 -0400, wrote:

On Thu, 21 Aug 2008 15:24:48 GMT, (Richard
Casady) wrote:

Every powerline has lightning protection, a
grounded wire above the power conductors. What does every electric
utility know? None the less lightning does hit powerlines. A long wire
lacks sharp points, if that makes a lot of difference.


That is certainly not true in Florida. The top wire on the MV
distribution poles around here is the medium voltage wire. The
grounded conductor is on the bottom. (actually the top of the
secondary triplex here.)


http://esteroriverheights.com/electr...20-240_bus.jpg

On the HV transmission lines they do put the ground on top tho.

This is 250KV and the ground is on top
http://members.aol.com/gfretwell/powerline.jpg

My mistake. I went for a country drive. The HV lines around here are
on two kinds of CorTen steel tower, galvanized ones, and wood,and
there are many of them. [Des Moines, Iowa] Indeed they have a grounded
wire above the energized ones. They would need lightning protection
more than the 22KV ones in front of the house. [The ones with the fist
size insulators, not the yard long ones.]

Casady

On Thu, 21 Aug 2008 12:48:27 -0400, wrote:

On Thu, 21 Aug 2008 13:58:54 GMT, (Richard
Casady) wrote:

I am always curious about how a boat takes a hit but I do have some
experience with a lightning rod. I put a 3' copper rod over my weather
station with a pointy stainless steel tip, connected to 2ga copper
wire and terminated in a ground rod (connected to my extensive house
grounding system)
It has been hit twice that I know of and I was about 30' away during
one of them. A mexican laborer was pretty much under it, plastered
against my garage door. Other than the poop reflex we were totally
unaffected.. The steel garage door he was plastered to is bonded to
the same grounding system as the lightning rod as is the wet concrete
driveway I was standing on.
We were fine. The weather station ... not so much ... either time.

000 wire and a ten foot long grounding rod, is the customary practice
with lightning rods.


The 2 ga does an excellent job of routing the shot. My ground
electrode system is a lot more extensive than a single rod. The proof
is in the pudding as they say. The only thing I have ever lost is the
serial port in the PC that hooks to the weather station and that is
because the weather station signal cable runs parallel to the ground
wire from the air terminal for about 20'.
I am a bit embarrassed that I did that but I didn't really think this
thing would attract lightning so well.
It should be noted that the PC was connected to my network and nothing
else was affected. In fact I am still typing on the same PC as we
speak. The only thing that went was the serial port.
The last time it took a hit the same thing happened. The serial port
on the lap top it was connected to wasn't even totally fried. It still
runs a modem, just not the weather station.
Next time around I am putting the weather station on a fiberglass pole
on the other corner of the house but I am keeping the air terminal
where it is.
If I was using the RF connection from the weather station I bet
nothing would have been hurt

The ten foot rod is the one that the electrical suppliers sell. It
isn't the only thing that will work. There is one in the ground under
pole mounted transformers. Has the neutral connected to it. Copper
plated steel, driven in with a sledge. Any kind of metal pipe you have
lying around will work.

Casady

"Richard Casady" wrote in message
...

The ten foot rod is the one that the electrical suppliers sell. It
isn't the only thing that will work. There is one in the ground under
pole mounted transformers. Has the neutral connected to it. Copper
plated steel, driven in with a sledge. Any kind of metal pipe you have
lying around will work.

Casady


Electron beam equipment used in vacuum deposition systems cause all kinds of
spikes on the ground plane due to high voltage arcing. (They operated at
10kv dc) The common practice for grounding is two, eight foot copper clad
steel rods, driven about 10-12 feet apart from each other.

Then, a solution of water and copper sulfate is poured along side the rods
and into the holes until an ohm meter reads one (1) ohm or less resistance
between the two rods. Almost impossible to accomplish, but it provided an
"out" for any complaints you might have to the electron beam power supply
manufacturer. Their first question would be "Did you establish a ground
plane as outlined in the manual?". If no, or only close, they were never
much help in resolving any problems.

Eisboch