On Oct 15, 10:54*am, Ian Jackson
wrote:


One reason for lightning conductors (and for grounding elevated
conductors, like radio antennas) is that it helps to stop a high
electrostatic charge from accumulating in the air immediately above
them. The intention is to PREVENT a direct lightning strike, rather than
conduct a strike to ground. Of course, if a direct strike DOES occur, an
antenna (and even a stout lightning conductor) may be seriously damaged.
--
Ian

The only problem with that is that the charge is so quickly
replenished
that I think trying to bleed off the charge is a waste of time.
Note the "brush" type conductors that supposedly dissipate the
charge to avoid a strike. They don't really work too well, and when
they do get struck, often you have blobs of molten metal flying
about.
The way I see it, the only way to really prevent a strike, and even
then I think it's iffy, is to provide a shape that does not stream
well.
And then have a lightning rod which does stream well to take the
strike vs the object that does not stream well.
IE: a rounded ball on top of a mast does not stream as well as
a sharp tip. This is why most flag poles have a ball on top.
To reduce the likelihood of streaming. And even those can still be
struck under some conditions. So I think trying to avoid a strike
using such methods is more wishful thinking than anything.
I look at it in a different way. I expect it to be struck, and it will
if it's any decent amount of distance above the surrounding objects.
It might take 6 months, or it might take 6 years, but it will be
struck some day. Count on it.
A strike does not know where it's going to hit until about the
last 150 yards or so. Then the streamers from the ground
are all pointing towards the down leader trying to entice it.
Usually the strongest streamer in the area will attract the
strike. And even that is never a sure thing. :/
So the best way to deal with lightning is to expect it to
strike sooner or later, and to provide the most efficient
path to ground when it happens.
A well grounded mast DOES NOT attract lightning any
better than a non grounded mast at the same location.
That's horse caca, and the OP can tell his friend I said so.
They will stream the same, and I consider the chances
of a direct strike about equal.
It's when you actually take a strike is when the differences
in grounding show up.
The well grounded mast will take the charge to ground
in an orderly military manner, and in most cases no
damage will occur.
The non grounded mast does not provide an orderly
path to ground, so the strike takes whatever path
has the least resistance. And even that path is likely
to be fairly high resistance and fireworks are likely
to occur. Houston, we have a problem.. :/
The OP did the proper thing by grounding his mast.
If properly grounded, if he does take a strike, the
mast will direct the charge to ground and little
damage should occur. This does not mean you
want a radio hooked up though. That takes extra
measures like suppressors, ground window, star
grounding, etc..
But at least he won't have to worry about burning the
house down.
I've had my mast directly struck more than once, and
I had no damage at all. Period. But my feed lines
were all grounded to my bulkhead outside the shack.
I don't leave them connected as I use no suppressors.
Two of those strikes were with me sitting in this chair
15 feet away from the base of the mast.
You can actually hear the difference between a strike
to a well grounded mast, and a strike to a poorly
grounded object.
The strike to the well grounded mast will be very quiet.
Just an arc sound like throwing a light bulb on the ground.
A strike to something poorly grounded like say a tree
will be much louder. More like a crack from a shotgun.
This is not to be confused with the overhead sonic boom
which both types of strikes will make. I'm just talking
about the local sound.
Anyway, that's my $12.47 worth from someone that lives
in lightning country and has taken multiple direct strikes
though the years.
If the OP wants some good lightning info, try searching for
Gary Coffman and lightning on google. I don't know if his
past posts are still archived, but they should be.
He had a lot of good posts on various aspects of lightning
protection.