Re: Zapping Camera Problem

[westom1@xxxxxxxxx]

On Thursday, May 23, 2013 6:36:32 AM UTC-4, ABLE1 wrote:

> Having a problem with continued Camera location being Zapped when a storm=
=20
> goes by.=20

  Robert Macy's reply was spot on.  Others misunderstood some of his points=
.  For example, conduit or other grounds that are that long are (essentiall=
y) non-existent.  For surge protection, even length of a wire is critical. =
 Even a sharp wire bend compromises protection.

  To resummarize his points.  Your camera 200 feet away must be handled as =
if two completely different structures.  Using the same protection method i=
mplemented between your home and the telco's CO.  Each structure must have =
its own single point earth ground. Camera will never be earthed by the buil=
ding's ground. Otherwise, a lightning strike to one building (ie the house)=
 is a direct lightning strike to electronics in the other structure (video =
section of a camera).

  Do not earth the camera.  That makes a camera the better and destructive =
connection to earth.  Earth every incoming conductor to that camera.  And a=
gain, the earthing must be low impedance - as short as possible (ie 'less t=
han 10 feet').

  This professional's application note demonstrates the concept - The Need =
for Coordinated Protection:
http://www.erico.com/public/library/fep/technotes/tncr002.pdf

  In your case, replace that antenna tower with a camera.  The tower and bu=
ilding both have their own single point earth ground (all four words are el=
ectrically significant).  Any wire that enter the building or camera must f=
irst connect to earth ground.  Either directly (ie the shield of a coax) or=
 via a protector (ie 12 VDC).  If any one wire in any cable violates that r=
ule, then damage can result either to electronics inside the building or ca=
mera.

  Also important.  Makes no difference if the wire is overhead or undergrou=
nd.  Same rules apply as that application note says.

  Do not earth a camera.  Earth the surge.  A major difference.  Even joint=
s in conduit compromise protection.  If a ground wire is inside a metallic =
conduit, then it also does not earth a surge.  It is not about wire thickne=
ss.  Most critical is conductor 'length'. No splices.  No sharp wire bends.=
 Otherwise impedance is too high - the earth ground connection all but does=
 not exist.

  A surge is electrically different from electricity that powers appliances=
.  Even wires must be routed with greatest care.  Protectors are simple sci=
ence.  Most important is the art of protection - single point earth ground.