In almost 45 years of ham operation I have never bothered with a "good"
ground connection. I am in what might be my last location and now have a
"real" tower (55' crank up). I understand the principles behind a single
ground, or at least I think I do. However, ideal requirements (as often
quoted in various codes and standards manuals) need to be matched with what
one can actually do.

I have several ground rods by the tower and one by the entry to my basement
shack. The tower-to-entry-point has two #10 wires in the trench (but not
not in the conduit) that connect the nearest of the tower ground rods to the
entry-point rod. The distance is about 45'.

From the entry point area to the rig is about 10' and has a single #10 wire.
Also from the rig area to the electrical panel is another #10 wire that is
about 40'.

Is this a reasonable arrangement? Is it better than nothing? Worse than
nothing?

I will shortly place two ICE units at the entry point on the two coax lines
from the tower. I am still considering what to do with the control
lines --- there are 12 for a SteppIR, 6 for a rotator, and 6 for a remote
coax switch.

Bill
W2WO

"Bill Ogden" wrote

I have several ground rods by the tower and one by the entry to my
basement
shack. The tower-to-entry-point has two #10 wires in the trench (but not
not in the conduit) that connect the nearest of the tower ground rods to
the
entry-point rod. The distance is about 45'.

From the entry point area to the rig is about 10' and has a single #10
wire.
Also from the rig area to the electrical panel is another #10 wire that is
about 40'.

Is this a reasonable arrangement? Is it better than nothing? Worse than
nothing?

Hi Bill, it's reasonable and better than most, providing the following is
also true:

The coax shields grounded at the tower (min. at the bottom, best top and
bottom), and again at the basement entrance single point ground. Shields
must be grounded before connection to an arrestor.

I will shortly place two ICE units at the entry point on the two coax
lines
from the tower. I am still considering what to do with the control
lines --- there are 12 for a SteppIR, 6 for a rotator, and 6 for a remote
coax switch.

Bill
W2WO

ICE also makes protection for control lines. I have no experience with them
in particular, but my six ICE coax arrestors have handled a lot of surge
from several strikes less than 100' away, two of which were within 50' of
antennas.

I would also add that the importance of the bonding between shack single
point ground and AC service entry point ground is critical to prevent ground
potential rise (GPR) from a nearby strike's energy from going through your
equipment via your own ground connections. The path in from ground and out
through the back of your equipment AC power cords will always exist, but
with proper bonding it will not be a destructive connection. Most stations
have this station-ground to mains-ground bonding conductor outside the
station, but I don't see the harm of having it inside either *if* it was a
very short distance [yours is NOT SHORT]. The shorter the route for this
bond the better, whatever path it may take. NEC requires it be less than
20'. Fat chance you say. Alternatives are to provide multiple ground rods
along a 20' path of this critical bond. That means change your bonding
conductor to run outside, from the station single point ground (rod), via a
couple additional rods, to the AC mains service entry ground (rod).

73,
Jack Painter
Virginia Beach VA

"Jack Painter" wrote in message
news:zbbnd.1127$wa1.571@lakeread04...
snip
The coax shields grounded at the tower (min. at the bottom, best top and
bottom), and again at the basement entrance single point ground. Shields
must be grounded before connection to an arrestor.


Jack - regarding your comment on grounding the shields BEFORE connection to
an arrestor: My arrestors are mounted on the common ground panel and the
coax is grounded via the coax connector to those arrestors. What is the
reason for a separate ground prior to that one. Maybe I misunderstood
something, but it seems redundant to have a separate ground a few inches
from that one.

In response to another's comments regarding protection of the SteppIR,
rotor, and other control lines: I use MOVs and .01 bypass caps on all those
lines in a box at the base of the tower and have another set of the same at
the entry panel box. Those components are mounted via European-style screw
terminal strips (12 positions per strip) obtained from Jameco via the Web.
Much cheaper than the same from Radio Shack or other sources. MOVs came
from Mouser. A lightning strike last year entered my shack via relay
control lines which were unprotected at that time. Hopefully, the new
arrangement will help.

73, Floyd - K8AC

This was answered off-line but for the group:

"Floyd Sense" wrote
"Jack Painter" wrote in message
snip
The coax shields grounded at the tower (min. at the bottom, best top and
bottom), and again at the basement entrance single point ground. Shields
must be grounded before connection to an arrestor.


Jack - regarding your comment on grounding the shields BEFORE connection
to
an arrestor: My arrestors are mounted on the common ground panel and the
coax is grounded via the coax connector to those arrestors. What is the
reason for a separate ground prior to that one. Maybe I misunderstood
something, but it seems redundant to have a separate ground a few inches
from that one.

Coax shield grounding must be accomplished at the tower top, tower base (on
ground level, not even 6" above!) and before the arrestor to comply with
protector manufacturer requirements and to be in keeping with best
engineering practices that are used nationwide in communication tower
designs. The grounding just before the arrestor is for two purposes: 1.
preventing unnecessary energy (whether capacitively or inductively coupled)
from challenging the gas tube, MOV, coil (or all three) mechanisms of a
protector, and 2: to help limit the differing potential available to
reverse-path voltage from a nearby strike in ground potential rise
conditions. A nearby strike can saturate the ground system, and a station
ground can reference hundreds of thousands of volts 'up' from the ground,
and 'out' via arrestors, phone, power cables to lower potential felt at some
distant point. Grounding cable shield at the station single point ground
thus helps maintain equipotential for both directions. Even if the station
coax arrestors are mounted on the master ground the additional grounding is
still helpful for voltage-division during saturated ground conditions. But
in all cases that ground bus mount must never be the only place the coax
shelding is grounded!


In response to another's comments regarding protection of the SteppIR,
rotor, and other control lines: I use MOVs and .01 bypass caps on all
those
lines in a box at the base of the tower and have another set of the same
at
the entry panel box. Those components are mounted via European-style
screw
terminal strips (12 positions per strip) obtained from Jameco via the Web.
Much cheaper than the same from Radio Shack or other sources. MOVs came
from Mouser. A lightning strike last year entered my shack via relay
control lines which were unprotected at that time. Hopefully, the new
arrangement will help.

73, Floyd - K8AC

Several amateurs have reported successful use of private design MOV on
control lines. While this could exceed commercially available equipment
specs in some cases, for those less familiar with such designs, they are
readily available in package-form to protect control lines.

Jack

On Fri, 19 Nov 2004 07:44:50 -0500, "Floyd Sense"
wrote:


"Jack Painter" wrote in message
news:zbbnd.1127$wa1.571@lakeread04...
snip
The coax shields grounded at the tower (min. at the bottom, best top and
bottom), and again at the basement entrance single point ground. Shields
must be grounded before connection to an arrestor.


Jack - regarding your comment on grounding the shields BEFORE connection to
an arrestor: My arrestors are mounted on the common ground panel and the
coax is grounded via the coax connector to those arrestors. What is the
reason for a separate ground prior to that one. Maybe I misunderstood
something, but it seems redundant to have a separate ground a few inches
from that one.

In response to another's comments regarding protection of the SteppIR,
rotor, and other control lines: I use MOVs and .01 bypass caps on all those
lines in a box at the base of the tower and have another set of the same at
the entry panel box. Those components are mounted via European-style screw
terminal strips (12 positions per strip) obtained from Jameco via the Web.
Much cheaper than the same from Radio Shack or other sources. MOVs came
from Mouser. A lightning strike last year entered my shack via relay
control lines which were unprotected at that time. Hopefully, the new
arrangement will help.

73, Floyd - K8AC




Floyd,

The real reason for grounding the coax shield at the entrance panel in
addition to having the protection device grounded is the voltage drop
between the connector and the coax line. The cable to connector
connection is usually not a good low resistance - high current joint
as far as lightning is considered. During a lightning strike you may
have considerable voltage drop across that junction.
Sometimes connectors are found to have been welded to the cable or
their threads welded due to lightning strikes because of the poor
connection at the connector. Other times the junction may get burned
open.
It can also melt the solder quickly in a soldered on connector which
would provide for an immediately poor connection.
However, lots of people do not do the extra grounding of the cable at
that point. Most are lucky if they get some sort of protection device
installed and a ground connected.

As Jack mentioned grounding the cable "at the bottom of the tower like
is used nation wide in tower designs" is ideal. But unfortunately that
is not how it usually gets done. Often the lines come off the tower at
6 to 10 feet above the ground to go to the building in a cable tray.
But it would indeed be best if they were taken all the way to ground
level before exiting the tower.

The reason being that during a strike the tower and associated lines
on it develop considerable voltage drop due to the high current being
conducted. Coming off the tower above ground is like taping a resistor
part way up from the ground end. Allowing more voltage to exit on the
lines rather than the potential at the base of the tower where it is
closer to ground. The tower usually has considerable inductance for
voltage to develop across.

Ideally lines should be grounded to the tower not only at the top and
bottom but at distances along the tower length as well. This is to
avoid flashovers that may puncture the line.

Lightning protection schemes are all about voltage drop. Most due to
inductance of the tower or other conductors carrying the current.
All conductors will have inductance and resistance and therefore
voltage drop if they are asked to carry lightning current. Keeping
things out of the middle of that path is the trick.

73
Gary K4FMX

Gary Schafer wrote in message . ..
On Fri, 19 Nov 2004 07:44:50 -0500, "Floyd Sense"


As Jack mentioned grounding the cable "at the bottom of the tower like
is used nation wide in tower designs" is ideal. But unfortunately that
is not how it usually gets done. Often the lines come off the tower at
6 to 10 feet above the ground to go to the building in a cable tray.
But it would indeed be best if they were taken all the way to ground
level before exiting the tower.

The reason being that during a strike the tower and associated lines
on it develop considerable voltage drop due to the high current being
conducted. Coming off the tower above ground is like taping a resistor
part way up from the ground end. Allowing more voltage to exit on the
lines rather than the potential at the base of the tower where it is
closer to ground. The tower usually has considerable inductance for
voltage to develop across.

I'm one of those who pulls the coax off the tower at around eight feet
and hangs it on a carrier wire from the tower to the outside wall near
the shack. In the past I've had end insulators at both ends of the
carrier wire. Your point about grounding the coax at the base of the
tower is well taken but is obviously not possible in these situations.
It occurs to me that the same effect can be accomplished by connecting
a #6 or #8 solid wire between the the coax shields where they bend
away from the tower and the base of the tower. Yes?

Taking it a bit further it also occurs to me that the carrier wire
could be connected to the base of the tower at the point where the
tower connects to the ground rods there, then up the tower and
connected to both the coax shields at the eight foot level and the
tower again. Then horizontally to the house wall with the coax, then
down to the ground rods just outside the shack to which the equipment
is also grounded. I'd also connect the coax shields to the carrier
wire again at the point where they turn away from the wire and go
through the wall. One hefty continuous, unbroken length of copper
wire. There would still be voltage differentials involved because
there is no escape from the inductances BUT . . . is my thinking in
the right direction here?


73
Gary K4FMX

w3rv

On 20 Nov 2004 17:59:12 -0800, (Brian Kelly) wrote:

Gary Schafer wrote in message . ..
On Fri, 19 Nov 2004 07:44:50 -0500, "Floyd Sense"


As Jack mentioned grounding the cable "at the bottom of the tower like
is used nation wide in tower designs" is ideal. But unfortunately that
is not how it usually gets done. Often the lines come off the tower at
6 to 10 feet above the ground to go to the building in a cable tray.
But it would indeed be best if they were taken all the way to ground
level before exiting the tower.

The reason being that during a strike the tower and associated lines
on it develop considerable voltage drop due to the high current being
conducted. Coming off the tower above ground is like taping a resistor
part way up from the ground end. Allowing more voltage to exit on the
lines rather than the potential at the base of the tower where it is
closer to ground. The tower usually has considerable inductance for
voltage to develop across.

I'm one of those who pulls the coax off the tower at around eight feet
and hangs it on a carrier wire from the tower to the outside wall near
the shack.

Theref are many installations like yours in existance. It was the
"common way" to do it some years ago. Not the best though.

In the past I've had end insulators at both ends of the
carrier wire. Your point about grounding the coax at the base of the
tower is well taken but is obviously not possible in these situations.
It occurs to me that the same effect can be accomplished by connecting
a #6 or #8 solid wire between the the coax shields where they bend
away from the tower and the base of the tower. Yes?

No that won't do much good. If you ground the coax shield to the tower
where it bends away from the tower you will have a much better (lower
inductance) to ground with the tower than what the wire would provide.
The wire would do almost no good at all when compared to the much
larger tower in parallel.


Taking it a bit further it also occurs to me that the carrier wire
could be connected to the base of the tower at the point where the
tower connects to the ground rods there, then up the tower and
connected to both the coax shields at the eight foot level and the
tower again.

Same as above. Grounding the carrier to the tower will do much more
than a wire to the ground rods at the tower. The carrier wire should
not be insulated from the tower. It and the coax should both be
grounded to the tower at the exit point. Otherwise you can have
flashover's to the carrier.

Then horizontally to the house wall with the coax, then
down to the ground rods just outside the shack to which the equipment
is also grounded. I'd also connect the coax shields to the carrier
wire again at the point where they turn away from the wire and go
through the wall. One hefty continuous, unbroken length of copper
wire. There would still be voltage differentials involved because
there is no escape from the inductances BUT . . . is my thinking in
the right direction here?

Connecting the carrier wire to the coax again at the house is a good
idea for the same reason you should connect it at the tower. to
prevent flashovers to the cables. The same situation exist on the
tower itself with lines running down. That is why they should be
grounded to the tower at several points. Especially on a tall tower.

The tower has inductance just like any piece of wire has. Although the
tower inductance is less than just a length of wire it still has
inductance. When lightning strikes the top, the tower and lines all
share the current to ground. The farther up from ground you are the
higher the voltage will be with respect to ground. It can be
significant. Especially on a smaller tower. Leaving the tower only a
few feet above ground with your coax line is putting that line at some
point above ground that can have high voltage.

The best way is to run the lines all the way to the bottom of the
tower, ground them there, and then run underground to the house to
your ground rods. Don't forget to also run a ground lead from your
house ground to your tower ground system too. Bury it along with the
cables. That will give you more contact with the earth as well as
tying the grounds together.

73
Gary K4FMX


73
Gary K4FMX

w3rv

Bill,

I would reroute the wire from your electrical panel directly to the
ground rod just outside your entry. Then from there run a single line
to your rig. This keeps the rig out of the middle of the ground
connections. If possible your AC line for the rig should run from
where that ground rod is. AC protectors should be put at that point
along with the coax protectors. Now you have a single point ground
system and the rig is not in the middle of things. All grounds are at
one point including all your protectors.

As far as the control wires, get some large MOV's and place one on
each line to ground. Again at your single ground point where your
ground rod is at the entrance.

With several control lines any surge energy that comes down them will
be shared by all. You can get by without gas tubes in this situation
as all those MOV's are effectively in parallel.

If you look inside a rotator protector like Polyphaser makes that is
all you will find in them.

The ground connection from your protection devices to your ground rod
should be as short and as large as you can manage. 3" wide copper
strap if the distance is a few feet. If it is a little longer run
place two copper straps edge to edge in parallel or a 6" strap.

It is important to have a low resistance / low inductance path to your
ground system. In addition you may want to add more ground rods /
radials to your entrance ground. Even just buried radials run out in
different directions away from that single ground rod that you have
will help lots. Placing an additional ground rod at the end of each is
still better. The big thing is to run the radials in different
directions to get some space between your ground rods. Ideally the
distance between rods should be the sum of their lengths.
The ground saturates when trying to dissipate energy in one place.
Spreading it out increases the amount of energy you can dump in a
given amount of time.

73
Gary K4FMX


On Thu, 18 Nov 2004 22:51:40 GMT, "Bill Ogden"
wrote:

In almost 45 years of ham operation I have never bothered with a "good"
ground connection. I am in what might be my last location and now have a
"real" tower (55' crank up). I understand the principles behind a single
ground, or at least I think I do. However, ideal requirements (as often
quoted in various codes and standards manuals) need to be matched with what
one can actually do.

I have several ground rods by the tower and one by the entry to my basement
shack. The tower-to-entry-point has two #10 wires in the trench (but not
not in the conduit) that connect the nearest of the tower ground rods to the
entry-point rod. The distance is about 45'.

From the entry point area to the rig is about 10' and has a single #10 wire.
Also from the rig area to the electrical panel is another #10 wire that is
about 40'.

Is this a reasonable arrangement? Is it better than nothing? Worse than
nothing?

I will shortly place two ICE units at the entry point on the two coax lines
from the tower. I am still considering what to do with the control
lines --- there are 12 for a SteppIR, 6 for a rotator, and 6 for a remote
coax switch.

Bill
W2WO