When Lightning Strikes
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I like tall trees. I like messing around with Stamps, weather sensors,
and video cameras. I also like to climb tall trees. But I don't care
for lightning striking tall trees that may happen to be equipped with
previously mentioned electronics. Do you know where I'm going with this?
I live in NH and we had some really good thunder storms last summer.
Well, in July I lost a CCD video camera, windcups, wind speed readout and
a 56K modem due to a lightning strike. I'm trying to prepare myself
ahead of time for next summer but am unsure as to how to best protect the
equipment, namely the Stamp, CCD camera and the One Wire sensors in the
Weather Station.
The sensors are located at the top of an Eastern White Pine at about 100
feet (30 meters) off the forest floor. The area is heavily wooded with
other pines, maples and oaks. My "sensor tree" is slightly taller than
the surrounding trees. I recently ran a length of #6 AWG copper wire
from ground to the peak and have two 8 foot (2.5M) grounding rods ready
to be hammered into the ground. The sensor data travels in shielded
twisted pair cable and RG-6 coax for the video signal. Both of these
cables run inside a 1” (25mm) plastic conduit the length of the tree.
I’m open to suggestions and comments on protecting against lightning
strikes. Some of my questions are:
Is it ok to tape the 6AWG grounding wire to the outside of the 1” plastic
conduit or is a separation recommended? (Taping it to the plastic
conduit is the easiest method)
Should the electronics at the top of the tree be housed in a metal
enclosure? (I currently have a plastic junction box in place.)
Should the grounding wire run up past the electronics to try to
“intercept” the lightning before it hits the electronics
Any help is appreciated,
Chris Dundorf
[noparse][[/noparse]Non-text portions of this message have been removed]
and video cameras. I also like to climb tall trees. But I don't care
for lightning striking tall trees that may happen to be equipped with
previously mentioned electronics. Do you know where I'm going with this?
I live in NH and we had some really good thunder storms last summer.
Well, in July I lost a CCD video camera, windcups, wind speed readout and
a 56K modem due to a lightning strike. I'm trying to prepare myself
ahead of time for next summer but am unsure as to how to best protect the
equipment, namely the Stamp, CCD camera and the One Wire sensors in the
Weather Station.
The sensors are located at the top of an Eastern White Pine at about 100
feet (30 meters) off the forest floor. The area is heavily wooded with
other pines, maples and oaks. My "sensor tree" is slightly taller than
the surrounding trees. I recently ran a length of #6 AWG copper wire
from ground to the peak and have two 8 foot (2.5M) grounding rods ready
to be hammered into the ground. The sensor data travels in shielded
twisted pair cable and RG-6 coax for the video signal. Both of these
cables run inside a 1” (25mm) plastic conduit the length of the tree.
I’m open to suggestions and comments on protecting against lightning
strikes. Some of my questions are:
Is it ok to tape the 6AWG grounding wire to the outside of the 1” plastic
conduit or is a separation recommended? (Taping it to the plastic
conduit is the easiest method)
Should the electronics at the top of the tree be housed in a metal
enclosure? (I currently have a plastic junction box in place.)
Should the grounding wire run up past the electronics to try to
“intercept” the lightning before it hits the electronics
Any help is appreciated,
Chris Dundorf
[noparse][[/noparse]Non-text portions of this message have been removed]
Comments
nearby sacrificial tree in an effort to find an easier earth for the
lightning.
Original Message
From: Christopher Dundorf [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=neFrJxcF_oPl3K8TZyDcOHmebLB-AT2IRzBL2rfONDqlPs9MIbP-KS6dPLTID_uEIQnPMfTxlPN3Rpk]cdundorf@j...[/url
Sent: Tuesday, February 18, 2003 11:20 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] When Lightning Strikes
I like tall trees. I like messing around with Stamps, weather sensors,
and video cameras. I also like to climb tall trees. But I don't care
for lightning striking tall trees that may happen to be equipped with
previously mentioned electronics. Do you know where I'm going with this?
I live in NH and we had some really good thunder storms last summer.
Well, in July I lost a CCD video camera, windcups, wind speed readout and
a 56K modem due to a lightning strike. I'm trying to prepare myself
ahead of time for next summer but am unsure as to how to best protect the
equipment, namely the Stamp, CCD camera and the One Wire sensors in the
Weather Station.
The sensors are located at the top of an Eastern White Pine at about 100
feet (30 meters) off the forest floor. The area is heavily wooded with
other pines, maples and oaks. My "sensor tree" is slightly taller than
the surrounding trees. I recently ran a length of #6 AWG copper wire
from ground to the peak and have two 8 foot (2.5M) grounding rods ready
to be hammered into the ground. The sensor data travels in shielded
twisted pair cable and RG-6 coax for the video signal. Both of these
cables run inside a 1" (25mm) plastic conduit the length of the tree.
I'm open to suggestions and comments on protecting against lightning
strikes. Some of my questions are:
Is it ok to tape the 6AWG grounding wire to the outside of the 1" plastic
conduit or is a separation recommended? (Taping it to the plastic
conduit is the easiest method)
Should the electronics at the top of the tree be housed in a metal
enclosure? (I currently have a plastic junction box in place.)
Should the grounding wire run up past the electronics to try to
"intercept" the lightning before it hits the electronics
Any help is appreciated,
Chris Dundorf
[noparse][[/noparse]Non-text portions of this message have been removed]
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guess, I would put the electronics in a metal box and run metal conduit up the
tree to it. I would also run the 6 ga wire along the side of the metal
conduit, attached to it every 8 foot or so, and to a ground rod at the bottom.
If the electronics box gets a direct hit, you can count on replacing it,
anything less this arrangement just might save the day.. Maybe some high
power EE's might comment on my suggestion and give an idea if it's even close
to being right.
Leroy
The type in metal oxide varistor
In the box labled contains at least the word.....type lightning.
That may get you started.
[noparse][[/noparse]Non-text portions of this message have been removed]
affected by lightning -- and it was rarely pretty. The "sacrificial tree"
approach does get used, though one's system must still be protected from the
EMI of the strike. Even a non-direct strke can create big problems in an
electrical system; especially a live electrical system.
-- Jon Williams
In a message dated 2/18/2003 12:26:45 PM Central Standard Time,
mrgadget@e... writes:
> I'm no expert but my train of thought would be to run the ground wires on a
> nearby sacrificial tree in an effort to find an easier earth for the
> lightning.
[noparse][[/noparse]Non-text portions of this message have been removed]
I live in NH also, and know what you mean with the lightning.
My experience with industrial electronics and big Midwest factories
is...nothing will protect from a direct lightning strike. 30 million volts at
50 million amps is just plain hard to deal with.
Incidental strikes are easier to deal with. We Optically Isolate as much as
possible. Try converting everything to serial and use fiber optic cable to
run down the tree. For power, if you could use Solar or wind to recharge
batteries, then there would be nothing conductive running up/down the tree.
Mov's work for a while then they fail, and you don't know it until the
electronics takes a hit.
Try <A HREF="www.brickwall.com">www.brickwall.com</A> They have some Inductive
Filter Assemblies that work
good.
Look into people/companies that do commercial radio towers for more help.
I know this is general, but it is a direction to get started.
Good Luck,
Alan Bradford
Plasma Technologies
[noparse][[/noparse]Non-text portions of this message have been removed]
about 15-20 feet away. Fiber optics do make a good of sense for
isolation and I think I'll find a radio tower guy and pick his/her brain.
Thanks for the ideas,
Chris
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The purpose of a lightning rod is NOT to 'attract the
stroke'. Instead, the rod is to bleed the difference
in static charge between the air and the ground, thus
preventing the stroke. The charge bleeds best from a
sharply pointed object, worst from a 'ball' shaped
object -- thus lightning rods should have a sharp point.
That said, a 'sacrificial tree' still makes sense, as
you want to neutralize the charge near your equipment
with as little interference as necessary.
I'm not sure what the magnitude of the 'bleed current'
would be (sets the size of the wire you run up the
tree)-- you should see the other references mentioned.
You might also want to visit Circuit Cellar Inc --
www.circellar.com, and search on Lightning. Steve
Ciarcia lives 'up north' also, and writes a lot
about lightning and various approaches to it.
--- In basicstamps@yahoogroups.com, Christopher Dundorf
<cdundorf@j...> wrote:
>
> I like the idea of using a sacrificial tree. Fortunately there is
one
> about 15-20 feet away. Fiber optics do make a good of sense for
> isolation and I think I'll find a radio tower guy and pick his/her
brain.
>
> Thanks for the ideas,
> Chris
>
> ________________________________________________________________
> Sign Up for Juno Platinum Internet Access Today
> Only $9.95 per month!
> Visit www.juno.com
electrodes. If it was easy to do it yourself, do you think they would still
be around? Besides, how can you tell your homemade deal works until its too
late?
Original Message
> The purpose of a lightning rod is NOT to 'attract the
> stroke'. Instead, the rod is to bleed the difference
> in static charge between the air and the ground, thus
> preventing the stroke. The charge bleeds best from a
> sharply pointed object, worst from a 'ball' shaped
> object -- thus lightning rods should have a sharp point.
>
> That said, a 'sacrificial tree' still makes sense, as
> you want to neutralize the charge near your equipment
> with as little interference as necessary.
>
> I'm not sure what the magnitude of the 'bleed current'
> would be (sets the size of the wire you run up the
> tree)-- you should see the other references mentioned.
>
> You might also want to visit Circuit Cellar Inc --
> www.circellar.com, and search on Lightning. Steve
> Ciarcia lives 'up north' also, and writes a lot
> about lightning and various approaches to it.