Re: lightning

[westom <westom1@xxxxxxxxx>]

On Sep 15, 12:41 pm, "Christopher Glaeser" <nos...@xxxxxxxxxx> wrote:
> An outdoor POE installation may include cat 5, 18 gauge for IR power, and 22
> gauge for alarms.  Do you use shielded versions of each?  Can you recommend
> a product / supplier for these?

  Appreciate first your problem.  Lightning seeks earth ground.  It
will find earth via paths that you provide - even through powered off
equipment.  Your task is to provide a path to earth that is non-
destructive.

  Lightning took a more conductive path to earth via wooden church
steeples. Yes, even wood is a conductor.  What did Franklin do?  Give
lightning a more conductive path to earth.  You don't stop surges.
Earth them on low impedance (not just low resistance) paths.

  Protection means every structure has a single point earth ground.
Use this application note as an example of two structures:
  http://www.erico.com/public/library/fep/technotes/tncr002.pdf
Every wire that enters or leaves each structure must connect to single
point earth.  Connected directly (ie cable TV or satellite dish) or
via a protector (telephone, AC electric, ethernet).   Every wire in
every cable must make that earthing connection.

  That connection must be low impedance.  That means short (ie 'less
than 10 feet'). no sharp wire bends. No splices.  Every grounding wire
separate until all meet at the earthing electrode.    A connection
that must be separated from other non-grounding wires.  Essential is a
low impedance (not just low resistance) connection to single point
ground.

  Where does energy dissipate?   Anything that might stop or block
only forces the current to create a massive voltage.  Current times
increased voltage means increased energy - damage.  Where do you want
energy dissipated?  It must dissipate someplace.  Anything that would
stop or absorb a surge will get blown through by that surge.  So
Franklin gave a direct lightning strike a high current, near zero
voltage connection to earth.  Near zero voltage means near zero
energy.  That is what your solution also must accomplish.  You want
energy, instead, dissipated in earth.

  Energy dissipate in earth does not hunt for earth ground
destructively via electronics.  That energy not inside a building
means protection inside all electronics is not overwhelmed.

  Another example might be a building with cameras on remote poles,
Therefore the pole must have its own single point earth ground.  A
protector connected short from each ethernet wire to that earth
ground.  That same wire enters a building at the service entrance to
also connect short to that single point ground.  Yes, all wires must
enter at a common service entrance to be properly earthed to the same
electrode.  See that app note?  Even underground wires must get the
same treatment.

  Where is energy harmlessly dissipated?  How did you make that short
connection to earth?