On 6/2/2013 9:58 AM, Jamie wrote:
bud-- wrote:

On 6/2/2013 7:39 AM, Jamie wrote:

Rich Webb wrote:

On Sun, 2 Jun 2013 02:05:29 -0400, "Humbled Survivor"
wrote:


Can I ground out my outdoor FM antenna from the pole?

Does the negative of the coaxial cable have to be grounded?

Which method is best for preventing lightening strikes?



Ref: NEC 810.15, 810.20, 810.21

Both the antenna mast and the signal lead-in (via a listed antenna
discharge unit) should be grounded IAW the above sections.


But the provisions of the NEC are not to protect from direct lightning
strikes to an antenna - much more elaborate protection is required.
They can provide protection from other surge sources, like near strikes.

For best protection the ground from antenna line entry protectors must
connect with a short wire to the power earthing system. You want to
minimize the voltage between power and antenna wires.

Nothing prevents lightning strikes but the effects can be mitigated.


actually, grounding it will attract near by strikes, but what ever..


Not according to what I read.


THe emf pulse of a strike directly on a grounded mast will more than
likely cook the front end of what ever is connected to it and maybe
even jump around a bit.


Hams with high antennas routinely protect from direct strikes to their
antennas. The rest of us are not likely to install the protection hams
install. But most of us do not have antennas as exposed as some ham
antennas.



I am a HAM, so if you're getting your information from there, then you
better read between the lines..

Ham radio towers get hit many times in a season, they are not immune
from it.

And hams with high antennas are very likely to have good protection from
a direct lightning strike.

The OP is very unlikely to have antenna that is significantly exposed.


NEC guide lines is there to protect people and that means the structures
people live or work in. THey don't give a rats ass about
antennas and devices connected to them, getting destroyed, they encourage
it. That way the lightning will be drawn away from the structure in hopes
that any thing conducting to ground, your antenna and mast, will steer
it away.

The provisions in the NEC, which Rich referred to, are not intended to
protect from a direct lightning strike and won't protect from a direct
strike. NEC compliant wiring will not 'draw' the lightning away from the
structure.