Hi gang
Just to upset the apple cart a bit, high trees do not necessarily
protect a large area from lightning.
In my past life as a range officer at a large shooting facility, we were
hit by lightning directly in front of the firing line during a storm.
The tree line was about 20 to 30 ft behind us and at least 50+ feet higher.
There was even evidence of arcing between 2 pieces of conduit stuck in
the ground about 5 ft apart. first and last time I saw a fire ball.
For induced charges from nearby strikes nothing beats a good ground and
lightning protector system.
If a direct hit, I hope your insurance is paid up.
My gps antennas are about 25 above ground just above my roof line. The
mast is grounded to 2 ground rods and the coax fed through gas tube
lightning protects. No problems even with hits several hundred yards away.
Ewing (Rix) Seacord
K2AVP/4/499
[email protected]
845-628-0892 Home
914-262-9186 Cell
914-233-3886 Skype Notebook
On 6/12/2012 1:31 AM, Hal Murray wrote:
[email protected] said:
But you know what? If you simply place an automotive "puck" type GPS
antenna on your roof you have to do the same thing. It must be grounded the
same way, same lightening protection and so on. So in the end you may as
well put up a professional looking and permanent steel mast. It is not
that much more work.
What about putting a skylight high on the roof and putting the antenna up in
it?
What's magic about inside vs outside the roof/skylight envelope?
-----------
I have a large pine tree out front. It's roughly 3x the height of my (one
story) house. What are the chances of any lightning hitting my house rather
than the tree? What if I put an antenna on the top of my house so the tree
is only 2x the height of my antenna?
Of course, that depends on how far the tree is from my house. Not far. Call
it 45 degrees from the back of my house to the top of the tree. An antenna
on the top of my house would probably be below that sight line.
Is there a good book or URL on lightning vs antennas? Again, I'm interested
in both the technical issues as well as the local zoning/legal issues.
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