Dave wrote:
"I would like to propose a grounding arrangement for my (hypothetical)
antenna and get some feedback on it."

Assuming the tower is not base insulated, start by grounding each leg of
the tower with a no. 6 AWG or larger cable directly to its own ground
rod.

Best lightning protection comes from folded driven element antennas
grounded directly at the tower top or other mounting point and
connecting the antenna with coax which is grounded again at the tower
base. If a folded driven element is not used, a short-circuited
quarter-wave stub can be connected directly across the antenna
drivepoint to supply the grounding to the tower that a folded element
provides.

Standard practice requires a no. 6 AWG or larger cable directly
connecting the base of the tower to the ground connection used by the
electrical service to the site.

For enhanced protection, large RF chokes as used in tower lighting
circuits in broadcast stations, are placed in each power wire, including
the neutral, between the electrical service and the radio connected to
the antenna. A-C capacitors are connected between each end of the
high-current chokes and a common connection directly to the station
ground. If there are 3 wires you need 6 caoacitors. Across each
capacitor you need a metal oxide varistor appropriate for the line volts
and the joules you may be called upon to dissipate when lightning
strikes. We also shunted the capavcitors with conventional thyrite
arrestors to back-up the MOV`s. This pi-filter with arresters worked
like gang busters. It is not excessive but did prove necessary for
solid-state equipment protection.

Best regards, Richard Harrison, KB5WZI

"Thomas Horne" wrote in message
link.net...
Jimmie D wrote:
"Dave" wrote in message
. ..
wrote in message
oups.com...
I would like to propose a grounding arrangement for my [hypothetical]
antenna and get some feedback on it. I have access to the solid-copper
cold-water pipe that enters my home through the basement wall close to
the basement floor.
bad start

This pipe is used [in addition to cold water] for
the service entrance [circuit breaker box] ground.
thats bad news

I was thinking of putting an antenna outside on a pole and running the
coax into the
basement.
nope, not the way to do it right.

Then I would strip back several inches of the outer jacket
of the coax [axposing the braided shield] and connect the coax braid to
the cold water pipe using several hose clamps. This should ground the
coax directly to the service ground - the single point ground for the
house.
except the single point shouldn't be 'inside' the house.

I would add an arrester near the ground point. I would then run
the coax upstairs [about 10 feet] to the radio, where it would [via the
PL-259] connect to the transceiver chassis. The radio chassis will be
electrically bonded to peripheral equipment chassis'.
the radio chassis should be connected to the same single point ground,
and not via just the coax shield.

It seems that in the unlikely event [low altitude, semi-urban area]
that the antenna were struck by lightning, the energy [albeit
significant] would have no reason to propagate up to my station. Even
though it may elevate my house ground by thousands of volts [with
respect to some other ground point], the station should ride up with it
- and little current should flow in the coax at the station.

Am I whistling Dixie?




Hopefully you are not really using the water pipe for a ground for your
electrical service. Hopefully your plumbing is just bonded to the
electrical ground. Dont even think about using this for lightning
protection. Nothing like having lightning run in on your plumbing while
taking a bath or have it run in on yor ground and eat about $7K worth of
test equipment(my bad).

Jimmie

Jimmie

DE KB3OPR

I am an electrician by craft. The US National Electric Code Requires that
underground metal water piping on the premise be used as a grounding
electrode for the electrical system. There is no way around it. No
matter how fast people talk you cannot avoid using an underground metal
piping system as a grounding electrode unless the electrical inspector is
incompetent.
--
Tom Horne

Tom you are confusing grounding with bonding, the plumbing should be bonded
to ground but not used for ground, at least this is getting to be the rule
in most places. I know that using the plumbing for ground is still
acceptaable in places and in a lot of places it is still acceptable if if
the local code permitted it at the time it was installed(grandfathering)..

Jimmie D wrote:


Hopefully you are not really using the water pipe for a ground for your
electrical service. Hopefully your plumbing is just bonded to the
electrical ground. Dont even think about using this for lightning
protection. Nothing like having lightning run in on your plumbing while
taking a bath or have it run in on yor ground and eat about $7K worth of
test equipment(my bad).

Jimmie

Jimmie

DE KB3OPR

I am an electrician by craft. The US National Electric Code Requires that
underground metal water piping on the premise be used as a grounding
electrode for the electrical system. There is no way around it. No
matter how fast people talk you cannot avoid using an underground metal
piping system as a grounding electrode unless the electrical inspector is
incompetent.
--
Tom Horne


Tom you are confusing grounding with bonding, the plumbing should be bonded
to ground but not used for ground, at least this is getting to be the rule
in most places. I know that using the plumbing for ground is still
acceptaable in places and in a lot of places it is still acceptable if if
the local code permitted it at the time it was installed(grandfathering)..



An electrician confusing grounding and bonding - that is pretty funny.

From the US National Electrical Code
“250.50 Grounding Electrode System
All grounding electrodes as described in 250.52(A)(1) through (A)(6)
that are present at each building or structure served shall be bonded
together to form the grounding electrode system.”

“250.52(A)(1) Metal Underground Water Pipe”
(10 feet or more metal in earth)

Using underground metal water pipe as a grounding electrode is REQUIRED.
And this has been a requirement for a very long time. Local codes may be
different from the NEC, but it is unlikely they are different on this.

And if you just "bond" metal water pipe it will work as a grounding
electrode anyway.

--
bud--

wrote:
I would like to propose a grounding arrangement for my [hypothetical]
antenna and get some feedback on it. I have access to the solid-copper
cold-water pipe that enters my home through the basement wall close to
the basement floor. This pipe is used [in addition to cold water] for
the service entrance [circuit breaker box] ground. I was thinking of
putting an antenna outside on a pole and running the coax into the
basement. Then I would strip back several inches of the outer jacket
of the coax [axposing the braided shield] and connect the coax braid to
the cold water pipe using several hose clamps. This should ground the
coax directly to the service ground - the single point ground for the
house. I would add an arrester near the ground point. I would then run
the coax upstairs [about 10 feet] to the radio, where it would [via the
PL-259] connect to the transceiver chassis. The radio chassis will be
electrically bonded to peripheral equipment chassis'.

It seems that in the unlikely event [low altitude, semi-urban area]
that the antenna were struck by lightning, the energy [albeit
significant] would have no reason to propagate up to my station. Even
though it may elevate my house ground by thousands of volts [with
respect to some other ground point], the station should ride up with it
- and little current should flow in the coax at the station.

Am I whistling Dixie?

Thanks,

-JJ


I'm sure not an expert on the subject but ARRL ran a good multipart
series in 2002 that might address some of your questions.

http://www.arrl.org/tis/info/pdf/0206056.pdf
0206056.pdf (application/pdf Object)

Good luck!

Chuck

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Maybe read PolyPhaser | The Authority On Lightning & Surge Protection

http://www.polyphaser.com/

Happy New year -- CL

"Caveat Lector" wrote in message
...
Maybe read PolyPhaser | The Authority On Lightning & Surge Protection

http://www.polyphaser.com/

Happy New year -- CL


THE BIBLE on grounding and bonding.as far as I am concerned.

try

http://www.w8ji.com/ground_systems.htm

bob

On Mon, 01 Jan 2007 11:14:20 -0600, Bob Miller
wrote:


try

http://www.w8ji.com/ground_systems.htm

Although he doesn't say so, Tom's towers are on top of a mountain.



bob
Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

On 1 Jan 2007 04:40:29 -0800, "
wrote:

I would like to propose a grounding arrangement for my [hypothetical]
antenna and get some feedback on it. I have access to the solid-copper
cold-water pipe that enters my home through the basement wall close to
the basement floor. This pipe is used [in addition to cold water] for
the service entrance [circuit breaker box] ground.

Hi OM,

You have the classic service ground connection.

I was thinking of
putting an antenna outside on a pole and running the coax into the
basement. Then I would strip back several inches of the outer jacket
of the coax [axposing the braided shield] and connect the coax braid to
the cold water pipe using several hose clamps.

This qualifies, in most respects, to code for grounding a continuous
wire and employing a method prescribed by code, clamping. However, it
would seem that clamping might deform the coax. You should
investigate your local code for alternatives as well as for
compliance.

This should ground the
coax directly to the service ground - the single point ground for the
house. I would add an arrester near the ground point.

Then you are breaking the run instead of just simply stripping the
jacket. Check code.

I would then run
the coax upstairs [about 10 feet] to the radio, where it would [via the
PL-259] connect to the transceiver chassis. The radio chassis will be
electrically bonded to peripheral equipment chassis'.

This is also classically known as a suicide connection. If you were
holding the PL-259 shell in one hand, and touched any, poorly
maintained metal chassis of the transceiver while plugging it in (or
removing it); then you might just be the fuse in a circuit about to
blow. I've seen my buddy draw sparks with just such an arrangement
before I convinced him to run a real, separate ground.

73's
Richard Clark, KB7QHC

" wrote in
oups.com:

I would like to propose a grounding arrangement for my [hypothetical]
antenna and get some feedback on it. I have access to the solid-copper

You haven't described here the antenna and its support structure, and
they are relevant.

One of the strategies for hardening a site against lightning is to divert
as much of the strike current to ground rather than having it flow in the
conductors within the facility. The value / necessity of this measure
will depend on the antenna, its support structure, nearby structures that
might protect your antenna to some extent, and the risk of lighting in
your locality.

cold-water pipe that enters my home through the basement wall close to
the basement floor. This pipe is used [in addition to cold water] for
the service entrance [circuit breaker box] ground. I was thinking of
putting an antenna outside on a pole and running the coax into the
basement. Then I would strip back several inches of the outer jacket
of the coax [axposing the braided shield] and connect the coax braid to
the cold water pipe using several hose clamps. This should ground the
coax directly to the service ground - the single point ground for the
house. I would add an arrester near the ground point. I would then run
the coax upstairs [about 10 feet] to the radio, where it would [via the
PL-259] connect to the transceiver chassis. The radio chassis will be
electrically bonded to peripheral equipment chassis'.

Lightning conductors need to be substantial enough to withstand the
strike scenario without physical failure (eg melting). A common scenario
is 20kA for 0.1s, but it does depend on the situation. Is your coax braid
and your termination / bonding method sufficient to survive strike
current?

Equipotential bonding of the lightning protection ground and the AC
service ground systems is important. Low resistance and more importantly
low inductance conductors that will withstand the current are required.

Depending on your coax shield as a bonding conductor from your equipment
to the ground point as you describe sounds unwise for several reasons,
but most notably because it uses coax connectors (and probably PL259s at
that) for the connection, they are not reliable enough, and they would
not be a permanent connection).

If your equipment runs on low voltage DC, do not assume that the power
supply provides a connection between the AC ground and the -ve DC lead,
some powersupplies have floating output. In any event, bonding of the
external metal of all equipment in your station to a single point ground
is advisable to reduce the risk of substantial potential differences
between equipments, and the risk that poses to life in the event of
lightning or even an electrical fault.

If addressing these issues seems extreme, it is probably a good indicator
that many ham station earth systems are quite inadequate, offset by the
low probability of an adverse event and not usually talked about when
poor implementation exacerbated the situation.

Like one of the other respondents, I recommend the Polyphaser site, it is
a usefull source that canvasses many of the issues.

Additionally, your wiring codes or standards may provide guidance or set
requirements, they do here.

Having done all that, and with better knowledge, review the risk, cost
and measures. You may not want to resource a lightning hardened solution
for 24x7 connection of the stations to antennas.

Owen