As a new ham, I am considering erecting a tower for
my antenna(s). As part of my research, I've been
reading about lightning protection, and now feel
I have a fair understanding of what I need to do
in order to protect both my radio gear and my home.
However, the thought occurred to me that if I
ercted a tower it would probably increase the odds
of lightning striking either it or a nearby object,
and while my house might be protected (or at least
I would be the one choosing to take the risk), what
about the neighbors? Even if the strike would be
directly on my tower, from what I've read there
could be enough induced voltage/current to damage
the 'unprotected' appliances of my neighbors, and
they might blame me for their losses (or even if
it doesn't hit the tower, they may still see it
as the cause of a nearby strike).
Has anyone heard of any such cases or am I
just worrying about the highly improbable?

Thanks,
Frank
KE5MJZ

KE5MMJZ wrote in news:slrnf180co.7j9.spam-
:

....
ercted a tower it would probably increase the odds
of lightning striking either it or a nearby object,
and while my house might be protected (or at least
I would be the one choosing to take the risk), what
about the neighbors? Even if the strike would be
directly on my tower, from what I've read there
could be enough induced voltage/current to damage
the 'unprotected' appliances of my neighbors, and
they might blame me for their losses (or even if
it doesn't hit the tower, they may still see it
as the cause of a nearby strike).
Has anyone heard of any such cases or am I
just worrying about the highly improbable?

Frank,

The existence of a tall conductor provides a measure of protection to
nearby structures. The zone is often defined by a "ball" of radius equal
to the height of the tall structure that is rolled on the ground to rest
against the tall structure, and structures between the contact with the
ground and tower, and under the ball are considered protected by the tall
structure, ie that lightning is much more likely to strike the tall
object. In this way, a tower often protects the nearby equipment hut from
direct strikes.

Having said that, there are two other effects you must consider:
- the way in which the discharge current on the tower is dealth with; and
- the fields in the nearby area from the discharge current.

The usual approach is to try to shunt as much of the discharge current to
ground. Nevertheless, some will enter your premises and you should pay
attention to equipotential bonding and single point earthing techniques
to minimise the voltages impressed across equipment interfaces, voltage
that may cause damage.

It is not just about equipment, personal safety is more important, but
provided you use earthing conductors sufficient to survive the lightning
discharges (and people of do not) and equipotential bonding, then
personal protection is fairly easily achieved.

Even if you have dealt with minimising interface voltages in your own
premises, the discharge current may give rise to a surge on the power
lines or metallic water services that couple to your neighbours relative
to each other or telecommunications services. It is conceivable that a
discharge to your tower might not cause damage to your installation but
could damage appliance in neighbouring premises... so I wouldn't call
your tower as protecting neighbours.

Owen

Owen Duffy wrote:

Frank,

The existence of a tall conductor provides a measure of protection to
nearby structures. The zone is often defined by a "ball" of radius equal
to the height of the tall structure that is rolled on the ground to rest
against the tall structure, and structures between the contact with the
ground and tower, and under the ball are considered protected by the tall
structure, ie that lightning is much more likely to strike the tall
object. In this way, a tower often protects the nearby equipment hut from
direct strikes.

I believe that the latest research indicates that the "rolling ball"
isn't as accurate as once believed (or necessarily better than the older
"cone of protection"). But the difference might be in the noise floor
for most ham installations.

"KE5MMJZ" wrote in message
...
As a new ham, I am considering erecting a tower for
my antenna(s). As part of my research, I've been
reading about lightning protection, and now feel
I have a fair understanding of what I need to do
in order to protect both my radio gear and my home.
However, the thought occurred to me that if I
ercted a tower it would probably increase the odds
of lightning striking either it or a nearby object,
and while my house might be protected (or at least
I would be the one choosing to take the risk), what
about the neighbors? Even if the strike would be
directly on my tower, from what I've read there
could be enough induced voltage/current to damage
the 'unprotected' appliances of my neighbors, and
they might blame me for their losses (or even if
it doesn't hit the tower, they may still see it
as the cause of a nearby strike).
Has anyone heard of any such cases or am I
just worrying about the highly improbable?

Thanks,
Frank
KE5MJZ


if the lightning is close enough to strike your tower, it was going to hit
in that general area anyway. your tower has no effect once you get up to
the heights where lightning starts... it can only effect that last little
jump to connect to the ground where the 'cone' or 'ball' of protection area
is commonly considered.

Jim Lux wrote in
:

Owen Duffy wrote:

Frank,

The existence of a tall conductor provides a measure of protection to
nearby structures. The zone is often defined by a "ball" of radius
equal to the height of the tall structure that is rolled on the
ground to rest against the tall structure, and structures between the
contact with the ground and tower, and under the ball are considered
protected by the tall structure, ie that lightning is much more
likely to strike the tall object. In this way, a tower often protects
the nearby equipment hut from direct strikes.

I believe that the latest research indicates that the "rolling ball"
isn't as accurate as once believed (or necessarily better than the
older "cone of protection"). But the difference might be in the noise
floor for most ham installations.



Agreed Jim. The case is better for the nearby equipment hut than the
typical residential building near a 50' tower.

BTW, the "rolling ball" is the recommended approach in Australian
Standard 1768-1991 which I think is still current.

Owen

KE5MMJZ wrote:
As a new ham, I am considering erecting a tower for
my antenna(s). As part of my research, I've been
reading about lightning protection, and now feel
I have a fair understanding of what I need to do
in order to protect both my radio gear and my home.
However, the thought occurred to me that if I
ercted a tower it would probably increase the odds
of lightning striking either it or a nearby object,
and while my house might be protected (or at least
I would be the one choosing to take the risk), what
about the neighbors? Even if the strike would be
directly on my tower, from what I've read there
could be enough induced voltage/current to damage
the 'unprotected' appliances of my neighbors, and
they might blame me for their losses (or even if
it doesn't hit the tower, they may still see it
as the cause of a nearby strike).
Has anyone heard of any such cases or am I
just worrying about the highly improbable?

I haven't heard of it. Just make sure that everything is grounded
according to the National Electric Code (NEC). There are sections
devoted especially for towers at residences.

I say this as one who works in an industrial environment with large
free-standing towers. Our gear must stay online with five nines of
reliability. We routinely take direct hits on our microwave gear and
nothing happens. It goes to ground. We may not notice a thing except
for a few connections which have been welded together ;-)

73,

Jake Brodsky, AB3A

On 2007-04-04, Dave wrote:

if the lightning is close enough to strike your tower, it was going to hit
in that general area anyway. your tower has no effect once you get up to
the heights where lightning starts... it can only effect that last little
jump to connect to the ground where the 'cone' or 'ball' of protection area
is commonly considered.

I was considering the possible situation that a strike would have hit my
neighbor's house, as it is higher than mine, but since the well-grounded
tower was there it would take the hit instead, but still damage their
TV, etc. due to the induced currents in the area, and they might blame
me for their losses (since the strike hit my tower) even though the tower
might have saved them from a direct hit.
From the responses it looks like I'm probably over-concerned.

Thanks,
Frank
KE5MJZ

Spam Collector wrote in
:

I was considering the possible situation that a strike would have hit
my neighbor's house, as it is higher than mine, but since the
well-grounded tower was there it would take the hit instead, but still
damage their TV, etc. due to the induced currents in the area, and
they might blame me for their losses (since the strike hit my tower)
even though the tower might have saved them from a direct hit.
From the responses it looks like I'm probably over-concerned.

It could.

IMHO, the neighbours would have a hard time proving that you were liable,
but don't get legal advice from me, ask a lawyer... and he will give you
two answers.

Yes, you are probably over-concerned. Worry about personal safety first,
and that is pretty much people on your own property.

Owen

On 5 Apr, 14:46, Owen Duffy wrote:
Spam Collector wrote :

I was considering the possible situation that a strike would have hit
my neighbor's house, as it is higher than mine, but since the
well-grounded tower was there it would take the hit instead, but still
damage their TV, etc. due to the induced currents in the area, and
they might blame me for their losses (since the strike hit my tower)
even though the tower might have saved them from a direct hit.
From the responses it looks like I'm probably over-concerned.

It could.

IMHO, the neighbours would have a hard time proving that you were liable,
but don't get legal advice from me, ask a lawyer... and he will give you
two answers.

Yes, you are probably over-concerned. Worry about personal safety first,
and that is pretty much people on your own property.

Owen

Owen,
the laws are different in Australia. In the U.S. laws are made first
without a ruling what the the actual "words" inferred where as
"intent" of the law in Australia and other places is of prime
importance. As time passes by words uttered can change their meaning
from the original intent thus solutions can be delayed for years where
nothing is really final. Also in the U.S. anybody can sue anybody and
with impunity where as in other countries the loser pays the costs of
the court action.In America the person with the most money nearly
always wins and the poor finish up in jail since each side pays his
own costs and only gets the attorney that he can afford before his
money runs out.You can even get away with murder here
if you have deep pockets and in a lot of cases charges will be dropped
or diminished if the County does not have enough money to pursue a
lengthy trial where you must bear in mind that the opportunity for
unlimited appeals depend on the depth of the pocket of the
accused.America is broke
financially and in a lot of cases criminals are not arrested or let
out of prison early to make room for new entrants! We tried to make an
Empire without sufficient money on hand and thus we lost a Country.
Art

On 04 Apr 2007 19:50:45 GMT, KE5MMJZ wrote:

As a new ham, I am considering erecting a tower for
my antenna(s). As part of my research, I've been
reading about lightning protection, and now feel
I have a fair understanding of what I need to do
in order to protect both my radio gear and my home.
However, the thought occurred to me that if I
ercted a tower it would probably increase the odds
of lightning striking either it or a nearby object,
and while my house might be protected (or at least
I would be the one choosing to take the risk), what
about the neighbors? Even if the strike would be
directly on my tower, from what I've read there
could be enough induced voltage/current to damage
the 'unprotected' appliances of my neighbors, and
they might blame me for their losses (or even if
it doesn't hit the tower, they may still see it
as the cause of a nearby strike).
Has anyone heard of any such cases or am I
just worrying about the highly improbable?

Thanks,
Frank
KE5MJZ

I'm just guessing but it would be tough to go into court and prove the
actions of a bolt of lightning that may or may not have been attracted
by your tower and then skipped to your neighbor's property and did
damage.

Where would the proof be on a bolt of lightning that lasted less than
a second and likely had no witnesses?

If your tower is up to spec on grounding paraphernalia, you ought to
be okay.

bob
k5qwg