Elecraft

OT: Groond rods and concrete

Classic

List

Threaded

32 messages Options

John K9UWA-2

Re: OT: Ground rods and concrete

If you have a 50 foot tower with a tribander on it among a bunch of 70 foot or
taller Trees then perhaps you will survive lightning strikes without major
damage. However if you have something like my situation things change
rapidly. I have three towers the tallest is 175 feet to the top antenna. Trees
are all at 75 feet or less. I am the neighborhood lightning rod. I installed this
tower in late 1988 and in early 1989 we sustained a major hit. It blew up
every radio computer the microwave the frig the TV sets. lots of coax and
many other things made from metal. My station is in northern Indiana so we
do get some nice thunderstorms. Not as bad as Florida but bad enough. My
Assigned Risk insurance company said you have 30 days to either get that
stuff all on the ground or install a "Commercial Grade" Grounding system.

For the How to do it please read this 96 page PDF from Polyphaser.
Polyphaser Grounding Guide

After discussion with a couple of the Polyphaser Engineers who were also
HAMS I purchsed all the goodies and we set about to create the ground
system. It includes Whole House protection from Any wire that comes or
goes from the house.

This tower gets at least a dozen major hits per year. Since 1989 when the
system was installed I have had Almost ZERO damage. The ONLY thing
damaged was about 5 years ago the Whole House Protector on the Main
Breaker box gave up its little life to save everything else in the house. I
replaced it with a new one and all has been excellent prior to and since that
time.

The suggested Polyphaser Tower Grounding system looks a lot like that of
the QST article from 2002 previously posted by one of our other posters.
Radials 8 of them coming out from the tower. Polyphaser said they needed
to be 1/3rd the length of the top antenna with 8 foot ground rods each 16
feet along the radial. And of course one of the radials goes to the house
where the Single Ground Window... big aluminum plate with many protectors
and two ground rods to hold it in place is located. And the Perimeter ground
progresses around the house from that location. In my case since I have
three towers in a triangle shape they said single run from tower to tower with
again 8 foot ground rod each 16 feet along the way. Then rather than the 8
Radials from the single tower there are two starting outward from each of
the other 2 shorter towers. #2 tower 130 foot and #3 88 foot tall. On those
towers are about 20 yagi antennas 5 rotors and many many antenna
switching boxes. Mostly Ameritron RCS-8V many modified as phase
controllers for stack yagis.
The back yard has 100 8 foot long ground rods connect by 1200 feet or 3/8"
ID copper tubing. Silver Soldered to the Ground Rods.

So read and heed the PDF from Polyphaser. It works!!

73
John k9uwa
John Goller, K9UWA & Jean Goller, N9PXF
Antique Radio Restorations
[hidden email]
Visit our Web Site at:
http://www.JohnJeanAntiqueRadio.com
4836 Ranch Road
Leo, IN 46765
USA
1-260-637-6426

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

Terry Posey

Re: OT: Ground rods and concrete

In reply to this post by Jim Brown-10

I expect that the Moderator will be ending this Off Top soon. However:

One of my clients operates a large 90 tower (all self-supported) microwave system here in Florida. Florida is often regarded as the lightning capital of the world. I have helped my client with repairing damaged (cracked) tower foundations. Approximately $1 Million have been spent over the last five years repairing concrete foundations that have embedded Ufer rods in addition to an extensive external grounding system comprised of radials and soil driven rods. No repairs have been needed to any of the tower foundations that do not have Ufer embedded rods.

I have noticed that the damaged foundations cracks seem to appear after 15 years of service. This could be evidence of long term repetitive internal stresses - perhaps stresses resulting from steam expansion of the concrete's internal moisture due to repetitive high energy lightning pulses to the Ufer rod. Of course, none of thought is provable.

In the meantime, I do not include Ufer ground rods in any tower foundation designs that I have professional responsibility.
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

Edward R Cole

Re: OT: Ground rods and concrete

In reply to this post by Doug Renwick

I should preface this by saying I live on the Pacific Coast of Alaska
(2 miles from salt water).

I worked in two-way communications for 30 years and recall all towers
having external copper lines from the top to ground rods external to
the concrete base. Most of the hardlines were equipped with grounding
kits tied to that ground rod.

Also, my house has no concrete slab (4-1/2 foot high crawl space with
concrete block foundation walls interior of the crawl space is lined
with HD plastic vapor barrier with bare ground floor under the
plastic). Attached garage is on concrete slab.

My 240vac service is buried from transformer box at property edge
with buried utilities for about 1/4 mile where utilities run on
wooden poles. There is a copper ground rod below my power meter box
with what appears to be No. 10 solid copper ground wire. Service
wiring is aluminum. Telephone service box is adjacent to power meter
and ties its ground to the same ground rod.

My ham shack is the third bedroom on opposite side of the house where
I installed a ten-foot copper ground rod. I have a tower at end of
house (about 40-feet from the ham radio entrance) and another tower
45-feet from the other end of the house. I run 120-foot 1-5/8 inch
hardline from that tower to the ham radio entrance and ground the
shield at both ends with a copper ground rod. The ground rod at the
tower is tied to ground radials (on ground surface) for my
inverted-L. To tie the radio ground rod to electric service ground
rod would require about 100-foot run around edge of the house.

However, I did run 45-foot of 240vac via the crawl space to the ham
shack with 4-conductor wire which has No. 10 copper safety wire tied
to ground at load center and at 60A breaker box in the shack, so all
shack grounds including the shack ground rod are tied back via that
cable. Main ground tie from 60A box to shack external ground rod is
via No. 8 (includes grounding of 4.2kV PS to earth ground).

Neither tower is bonded to a ground rod, so I have no lightning
protection, though LMR-600 line on the tower ties the top antenna
structure to the ground where the 7-16 DIN coax connection is made
with the 1-5/8 line. That may offer some static drain but not lightning rated.

Fortunately the maritime climate does not produce lightning wx. I
have heard thunder maybe three times and seen a couple lightning
flashes over the 25 years living in this area. Not saying it can't
happen but the risk seems minuscule. BTW no lightening crash noise
on 80m in summer (except that propagated by ionosphere from somewhere
hundreds or thousands miles away).

73, Ed - KL7UW
http://www.kl7uw.com
Dubus-NA Business mail:
[hidden email]

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

Ronnie Hull

Re: OT: Ground rods and concrete

In reply to this post by Terry Posey

some 40 years ago, maybe longer I put up a 50' rohn 25G tower. Dug the hole
and set the tower base in it alone with a 12'
3/4" ground rod and poured the cement, left about 6" of ground rod
protruding. I bonded to that rod and grounded the tower.
3 years later I had a huge lightning strike on my tower and yes.. it cracked
that base.

never again

Ronnie W5SUM

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

Ken G Kopp

Re: OT: Ground rods and concrete

In reply to this post by Doug Renwick

I was the first to use the term "exploding tower base" in this discussion.
The term "exploding" was probably not correct. As several others have
phrased it, an instant expansion of steam is more correct. Concrete is
never totally "dry" in the context of this conversation.

I witnessed lightening blowing apart the two tower bases I spoke of in
person, directly, and in real-time. It happened in the mid-sixties at the
St. Petersburg, FL Coast Guard base. As someone else has mentioned;
the Tampa Bay region has the highest incidence of lightening in the
Western Hemisphere. To the one of you who accused my of lying ...
I was there ... you weren't.

At the time I was an ET aboard the USC&GS (Now NOAA) Oceanographic
Survey ship Hydrographer/WTEI and we were in the area deliberately
attracting lightening with balloon-hoisted cables. I -do- know something
about the infinite uncertainty of lightning.

I'm a retired electric power company two-way radio tech and have probably
dealt with more types of towers than most of you. Large electric
transmission
line towers are almost always set on four concrete piers, and are grounded
with (usually) copper straps cad-welded to each tower leg and connected to
ground rods a bit away from the cement. Each of us can search long enough
to find "facts" that support our various positons, especially on today's
Internet.

Here in the mountains of the West ... as well other regions ... finding and
maintaining a "good" ground at a radio site atop a mountain can be a
"challenge". It's almost never done with ground rods. My power company
employer has several hundred mountain-top microwave and/or radio sites.
Been there, done that, as they say.

One responder spoke of fitting a copper pipe with a garden hose fitting and
"flushing" it into the ground. That works very well, and is how some of my
14 grounds are installed. It helps if the downward end is partly
flattened, BTW.

A much bigger problem overall than lightening is water collecting in tower
legs,
especially in climates where it can rust (undetected) from the inside and /
or
freeze and split one or more legs. There's an accepted way to avoid this.

73!

Ken Kopp - K0PP

On Apr 18, 2017 at 4:30 PM, <[hidden email]> wrote:

> some 40 years ago, maybe longer I put up a 50' rohn 25G tower. Dug the
> hole

and set the tower base in it alone with a 12' 3/4" ground rod and
poured the
cement, left about 6" of ground rod protruding. I bonded to that rod
and grounded
the tower. 3 years later I had a huge lightning strike on my tower and
yes.. it cracked
that base.

never again

Ronnie W5SUM

> ______________________________________________________________
>
>
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

Randy Lake

Re: OT: Ground rods and concrete

This has been bugging me for a while and I am now in a mindframe to comment.
Lightening:
light·en·ing
ˈlītniNG/
*noun*

1. a drop in the level of the uterus during the last weeks of pregnancy
as the head of the fetus engages in the pelvis.

Come on !!

Randy
N1KWF

On Tue, Apr 18, 2017 at 7:39 PM, Ken G Kopp <[hidden email]> wrote:

> I was the first to use the term "exploding tower base" in this discussion.
> The term "exploding" was probably not correct. As several others have
> phrased it, an instant expansion of steam is more correct. Concrete is
> never totally "dry" in the context of this conversation.
>
> I witnessed lightening blowing apart the two tower bases I spoke of in
> person, directly, and in real-time. It happened in the mid-sixties at the
> St. Petersburg, FL Coast Guard base. As someone else has mentioned;
> the Tampa Bay region has the highest incidence of lightening in the
> Western Hemisphere. To the one of you who accused my of lying ...
> I was there ... you weren't.
>
> At the time I was an ET aboard the USC&GS (Now NOAA) Oceanographic
> Survey ship Hydrographer/WTEI and we were in the area deliberately
> attracting lightening with balloon-hoisted cables. I -do- know something
> about the infinite uncertainty of lightning.
>
> I'm a retired electric power company two-way radio tech and have probably
> dealt with more types of towers than most of you. Large electric
> transmission
> line towers are almost always set on four concrete piers, and are grounded
> with (usually) copper straps cad-welded to each tower leg and connected to
> ground rods a bit away from the cement. Each of us can search long enough
> to find "facts" that support our various positons, especially on today's
> Internet.
>
> Here in the mountains of the West ... as well other regions ... finding and
> maintaining a "good" ground at a radio site atop a mountain can be a
> "challenge". It's almost never done with ground rods. My power company
> employer has several hundred mountain-top microwave and/or radio sites.
> Been there, done that, as they say.
>
> One responder spoke of fitting a copper pipe with a garden hose fitting and
> "flushing" it into the ground. That works very well, and is how some of my
> 14 grounds are installed. It helps if the downward end is partly
> flattened, BTW.
>
> A much bigger problem overall than lightening is water collecting in tower
> legs,
> especially in climates where it can rust (undetected) from the inside and /
> or
> freeze and split one or more legs. There's an accepted way to avoid this.
>
> 73!
>
> Ken Kopp - K0PP
>
>
> On Apr 18, 2017 at 4:30 PM, <[hidden email]> wrote:
>
> > some 40 years ago, maybe longer I put up a 50' rohn 25G tower. Dug the
> > hole
>
> and set the tower base in it alone with a 12' 3/4" ground rod and
> poured the
> cement, left about 6" of ground rod protruding. I bonded to that rod
> and grounded
> the tower. 3 years later I had a huge lightning strike on my tower and
> yes.. it cracked
> that base.
>
> never again
>
> Ronnie W5SUM
>
> > ______________________________________________________________
> >
> >
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

--
Randy Lake N1KWF
73 Gunn Rd.
Keene,NH
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

Matt Zilmer-3

Re: OT: Ground rods and concrete

Time to update that list of frequently misspelled words. It is very
long, but also distinguished.

How about it's versus its? The first is a contraction, and the second
is a possessive. I think, from experience, that this is the single most
common spelling error that I see from English-first writers.

/me ducks. I'm SURE this is off topic.

73,

matt W6NIA

On 4/18/2017 5:03 PM, Randy Lake wrote:

> This has been bugging me for a while and I am now in a mindframe to comment.
> Lightening:
> light·en·ing
> ˈlītniNG/
> *noun*
>
> 1. a drop in the level of the uterus during the last weeks of pregnancy
> as the head of the fetus engages in the pelvis.
>
> Come on !!
>
> Randy
> N1KWF
>
>
> On Tue, Apr 18, 2017 at 7:39 PM, Ken G Kopp <[hidden email]> wrote:
>
>> I was the first to use the term "exploding tower base" in this discussion.
>> The term "exploding" was probably not correct. As several others have
>> phrased it, an instant expansion of steam is more correct. Concrete is
>> never totally "dry" in the context of this conversation.
>>
>> I witnessed lightening blowing apart the two tower bases I spoke of in
>> person, directly, and in real-time. It happened in the mid-sixties at the
>> St. Petersburg, FL Coast Guard base. As someone else has mentioned;
>> the Tampa Bay region has the highest incidence of lightening in the
>> Western Hemisphere. To the one of you who accused my of lying ...
>> I was there ... you weren't.
>>
>> At the time I was an ET aboard the USC&GS (Now NOAA) Oceanographic
>> Survey ship Hydrographer/WTEI and we were in the area deliberately
>> attracting lightening with balloon-hoisted cables. I -do- know something
>> about the infinite uncertainty of lightning.
>>
>> I'm a retired electric power company two-way radio tech and have probably
>> dealt with more types of towers than most of you. Large electric
>> transmission
>> line towers are almost always set on four concrete piers, and are grounded
>> with (usually) copper straps cad-welded to each tower leg and connected to
>> ground rods a bit away from the cement. Each of us can search long enough
>> to find "facts" that support our various positons, especially on today's
>> Internet.
>>
>> Here in the mountains of the West ... as well other regions ... finding and
>> maintaining a "good" ground at a radio site atop a mountain can be a
>> "challenge". It's almost never done with ground rods. My power company
>> employer has several hundred mountain-top microwave and/or radio sites.
>> Been there, done that, as they say.
>>
>> One responder spoke of fitting a copper pipe with a garden hose fitting and
>> "flushing" it into the ground. That works very well, and is how some of my
>> 14 grounds are installed. It helps if the downward end is partly
>> flattened, BTW.
>>
>> A much bigger problem overall than lightening is water collecting in tower
>> legs,
>> especially in climates where it can rust (undetected) from the inside and /
>> or
>> freeze and split one or more legs. There's an accepted way to avoid this.
>>
>> 73!
>>
>> Ken Kopp - K0PP
>>
>>
>> On Apr 18, 2017 at 4:30 PM, <[hidden email]> wrote:
>>
>>> some 40 years ago, maybe longer I put up a 50' rohn 25G tower. Dug the
>>> hole
>> and set the tower base in it alone with a 12' 3/4" ground rod and
>> poured the
>> cement, left about 6" of ground rod protruding. I bonded to that rod
>> and grounded
>> the tower. 3 years later I had a huge lightning strike on my tower and
>> yes.. it cracked
>> that base.
>>
>> never again
>>
>> Ronnie W5SUM
>>
>>> ______________________________________________________________
>>>
>>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
>>
>
>

--
"A delay is better than a disaster."
-- unknonwn

Matt Zilmer, W6NIA
[Shiraz]

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

Rick Dettinger-3

Re: OT: Ground rods and concrete

Thyir’er we go!

73,
Rick K7MW

> On Apr 18, 2017, at 6:01 PM, Matt Zilmer <[hidden email]> wrote:
>
> Time to update that list of frequently misspelled words. It is very long, but also distinguished.
>
> How about it's versus its? The first is a contraction, and the second is a possessive. I think, from experience, that this is the single most common spelling error that I see from English-first writers.
>
> /me ducks. I'm SURE this is off topic.
>
> 73,
>
> matt W6NIA
>
>
> On 4/18/2017 5:03 PM, Randy Lake wrote:
>> This has been bugging me for a while and I am now in a mindframe to comment.
>> Lightening:
>> light·en·ing
>> ˈlītniNG/
>> *noun*
>>
>> 1. a drop in the level of the uterus during the last weeks of pregnancy
>> as the head of the fetus engages in the pelvis.
>>
>> Come on !!
>>
>> Randy
>> N1KWF
>>
>>
>> On Tue, Apr 18, 2017 at 7:39 PM, Ken G Kopp <[hidden email]> wrote:
>>
>>> I was the first to use the term "exploding tower base" in this discussion.
>>> The term "exploding" was probably not correct. As several others have
>>> phrased it, an instant expansion of steam is more correct. Concrete is
>>> never totally "dry" in the context of this conversation.
>>>
>>> I witnessed lightening blowing apart the two tower bases I spoke of in
>>> person, directly, and in real-time. It happened in the mid-sixties at the
>>> St. Petersburg, FL Coast Guard base. As someone else has mentioned;
>>> the Tampa Bay region has the highest incidence of lightening in the
>>> Western Hemisphere. To the one of you who accused my of lying ...
>>> I was there ... you weren't.
>>>
>>> At the time I was an ET aboard the USC&GS (Now NOAA) Oceanographic
>>> Survey ship Hydrographer/WTEI and we were in the area deliberately
>>> attracting lightening with balloon-hoisted cables. I -do- know something
>>> about the infinite uncertainty of lightning.
>>>
>>> I'm a retired electric power company two-way radio tech and have probably
>>> dealt with more types of towers than most of you. Large electric
>>> transmission
>>> line towers are almost always set on four concrete piers, and are grounded
>>> with (usually) copper straps cad-welded to each tower leg and connected to
>>> ground rods a bit away from the cement. Each of us can search long enough
>>> to find "facts" that support our various positons, especially on today's
>>> Internet.
>>>
>>> Here in the mountains of the West ... as well other regions ... finding and
>>> maintaining a "good" ground at a radio site atop a mountain can be a
>>> "challenge". It's almost never done with ground rods. My power company
>>> employer has several hundred mountain-top microwave and/or radio sites.
>>> Been there, done that, as they say.
>>>
>>> One responder spoke of fitting a copper pipe with a garden hose fitting and
>>> "flushing" it into the ground. That works very well, and is how some of my
>>> 14 grounds are installed. It helps if the downward end is partly
>>> flattened, BTW.
>>>
>>> A much bigger problem overall than lightening is water collecting in tower
>>> legs,
>>> especially in climates where it can rust (undetected) from the inside and /
>>> or
>>> freeze and split one or more legs. There's an accepted way to avoid this.
>>>
>>> 73!
>>>
>>> Ken Kopp - K0PP
>>>
>>>
>>> On Apr 18, 2017 at 4:30 PM, <[hidden email]> wrote:
>>>
>>>> some 40 years ago, maybe longer I put up a 50' rohn 25G tower. Dug the
>>>> hole
>>> and set the tower base in it alone with a 12' 3/4" ground rod and
>>> poured the
>>> cement, left about 6" of ground rod protruding. I bonded to that rod
>>> and grounded
>>> the tower. 3 years later I had a huge lightning strike on my tower and
>>> yes.. it cracked
>>> that base.
>>>
>>> never again
>>>
>>> Ronnie W5SUM
>>>
>>>> ______________________________________________________________
>>>>
>>>>
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:[hidden email]
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> Message delivered to [hidden email]
>>>
>>
>>
>
> --
> "A delay is better than a disaster."
> -- unknonwn
>
> Matt Zilmer, W6NIA
> [Shiraz]
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

riese-k3djc

Re: OT: Ground rods and concrete

In reply to this post by Doug Renwick

I sure hope so

Bob K3DJC

On Tue, 18 Apr 2017 18:10:48 -0400 "Terry Posey" <[hidden email]>
writes:

> I expect that the Moderator will be ending this Off Topic soon.
>
> However:
>
> One of my clients operates a large 90 tower (all self-supported)
> microwave
> system here in Florida. Florida is often regarded as the lightning
> capital
> of the world. I have helped my client with repairing damaged
> (cracked)
> tower foundations. Approximately $1 Million have been spent over
> the last
> five years repairing concrete foundations that have embedded Ufer
> rods in
> addition to an extensive external grounding system comprised of
> radials and
> soil driven rods. No repairs have been needed to any of the tower
> foundations that do not have Ufer embedded rods.
>
> I have noticed that the damaged foundations cracks seem to appear
> after 15
> years of service. This could be evidence of long term repetitive
> internal
> stresses - perhaps stresses resulting from steam expansion of the
> concrete's
> internal moisture due to repetitive high energy lightning pulses to
> the Ufer
> rod. Of course, none of that thought is easily provable.
>
> In the meantime, I do not include Ufer ground rods in any tower
> foundation
> designs that I have professional responsibility.
>
> Terry K4RX
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

Bill K9YEQ

Re: OT: Ground rods and concrete

In reply to this post by David Gilbert

I have a deceased HAM buddy who espoused grounding to the nth degree. His recommendation, especially for his on premise cell phone towers, was to have as much metallic in the ground to detract large lightening hits to bypass radios and go to ground. K9KGM ( google his stuff) was his call and he not only believed but lived through major lightening hits to his towers, and counselled any of those he consulting with. You need adequate metal in the ground to dissipate the effects of a lightning strike. This doesn't guarantee against damage but certainly will help avoid the effect of a strike. Now the problem is: I have never been hit, therefore I am doing the right thing. :-) Or, I have insurance, so what does it matter? Thus the issues are answered?

73,
Bill
K9YEQ

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of David Gilbert
Sent: Tuesday, April 18, 2017 2:26 AM
To: Rick Dettinger <[hidden email]>
Cc: [hidden email]
Subject: Re: [Elecraft] OT: Ground rods and concrete

You also have many thousands of ham radio towers in northwest 7 land with either Ufer grounds or embedded tower bases. You tell me how many of them have exploded during lightning strikes, and how that justifies the admonition to "never encase a ground rod in a tower base".

I once did an extensive internet search trying to find documented examples of concrete structures that had exploded from the inside out due to internal grounded conductors. I couldn't find a single one.
Maybe you can find one, and if so I'd like to see the link. I did find several instances of damage to concrete structures from lightning hits, but all of them had external damage from simple lightning strikes. Most other damage was attributed to the fact that there wasn't any grounding at all ... i.e., an ungrounded structure on top of a concrete base.

From a theoretical point of view, I could picture a discharge causing more damage from insufficient metal in the concrete rather than too much. Spread the current ... minimize the heat buildup. If you want to argue that a single ground rod in a concrete base is a poor idea, OK ...
I can buy that. But these other blanket statements are garbage science.

Dave AB7E

On 4/17/2017 10:45 PM, Rick Dettinger wrote:

> A Uber ground was developed for dry areas during WW2. In damp areas, the concrete can do just what happened in the concrete pole test.
>
> Per Wikipedia article:
> "A disadvantage of Ufer grounds is that the moisture in the concrete can flash into steam during a lightning strike or similar high energy fault condition. This can crack the surrounding concrete and damage the building foundation.”
>
> We have plenty of damp soil in northwest 7 land.
>
> Best,
> Rick
>
>> On Apr 17, 2017, at 9:57 PM, David Gilbert <[hidden email]> wrote:
>>
>>
>> That isn't even close to being the same condition and only serves to help perpetuate a stupid myth that refuses to die among the ill informed. Anyone that doesn't understand that a Ufer ground is essentially multiple ground rods encased in concrete is indeed ill informed. And anyone who doesn't understand the mechanisms and considerations behind a Ufer ground shouldn't be making contributions to threads like this.
>>
>> Sorry for the ire displayed by me here, but this stupid topic keeps surfacing year after year in ham radio circles ... and specifically this forum ... without the least bit of thoughtful consideration behind it. I'm tired of our hobby, supposedly a technically based one, being subject to definitively stated exhortations that are so demonstrably wrong.
>>
>> Dave AB7E
>>
>>
>>
>> On 4/17/2017 9:09 PM, Rick Dettinger wrote:
>>> I don’t think its a myth. In the early 1970’s, the power company I worked for was testing out some hollow reinforced concrete poles. There was considerable concern by the line workers that the poles might be more dangerous to work on than wooden poles, in the event of an accident. To check this, we installed one of the poles in a sub station, and wrapped a 26KV 1200 amp feeder conductor around the pole. When the station breaker was closed, the pole exploded dramatically, with a large fireball. The results might have something to do with moisture content in the concrete. The results convinced us to only use the poles on transmission lines that wouldn’t be worked hot, like we did with distribution lines. Of course, the power levels are much higher in lightening strikes. The conduction paths should similar from encapsulated ground rods in a tower base to Earth.
>>>
>>> 73,
>>> Rick K7MW
>>>
>>>
>>>
>>>> On Apr 17, 2017, at 8:32 PM, Doug Renwick <[hidden email]> wrote:
>>>>
>>>> That myth refuses to die. I have 5 concrete tower bases with ground
>>>> rods partially encased and never a worry about an exploding base.
>>>>
>>>> Doug
>>>>
>>>>
>>>> -----Original Message-----
>>>>
>>>> -NEVER- encase a ground rod in concrete ... especially a tower base.
>>>>
>>>> As a retired 2-way radio tech, I'm aware of two towers that had to
>>>> be re-installed because of lightening strikes exploding their concrete bases.
>>>>
>>>> 73!
>>>>
>>>> Ken - K0PP
>>>>
>>>>
>>>>
>>>> ---
>>>> This email has been checked for viruses by Avast antivirus software.
>>>> https://www.avast.com/antivirus
>>>>
>>>> ______________________________________________________________
>>>> Elecraft mailing list
>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>> Post: mailto:[hidden email]
>>>>
>>>> This list hosted by: http://www.qsl.net Please help support this
>>>> email list: http://www.qsl.net/donate.html Message delivered to
>>>> [hidden email]
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:[hidden email]
>>>
>>> This list hosted by: http://www.qsl.net Please help support this
>>> email list: http://www.qsl.net/donate.html Message delivered to
>>> [hidden email]
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net Please help support this
>> email list: http://www.qsl.net/donate.html Message delivered to
>> [hidden email]
>

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email]
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

Dave-7

Re: OT: Ground rods and concrete

In reply to this post by Ken G Kopp

Let me inject an experience that occurred while I was a field engineer
for the phone co. working in Miami. We had a buried cable that ran
diagonally across an open green area. About 1/3 of the way across was
what we called a 'hand hole', a shallow pit where a splice or repair
had been done. It is back filled and, once the grass recovers, no one
knows it is there. Lightning struck in the vicinity. The telco cable
has the nice aluminum sheath and is well grounded. The lightning hops
onto that in preference to running through the ground. The water in
the hand hole exploded and left a small crater. The hole was about 2'
deep and 3' x 5'.

This makes perfectly good sense to me. You have water constricted into
a small enclosure. The lightning electrode, in this case the telco
cable, gets very hot very quickly. The water turns to steam and
explodes. Nothing surprising about that.

Let me also mention that the experts will tell us to not use solder on
any grounding conductors as the solder will melt. Well . . . water
boils at an appreciably lower temp than solder melts. What has
happened to the water in the vicinity of the lightning electrode
before the solder has had time to melt?

As for assertions that exploding Ufer grounds are a myth, I can tell
you for certain that the crater in Miami was not a myth. I kept a
photo of it on my desk for a few months to show those curious.

Experience tells me that Ufer grounds are, in general, a terrible
idea. There is very little reason to risk a building or tower
foundation to save the few $$$ of installing a correct ground system.
Ufer grounds may be OK, indeed preferred, in places like West TX, NM,
AZ, and parts of So CA, or in other very dry locations. But to use or
recommend them in locations with much moisture is asking for trouble.
In any location with much moisture, concrete will have the same water
content as the surrounding soil.

73 de dave
ab9ca/4

On 4/18/17 6:39 PM, Ken G Kopp wrote:

> I was the first to use the term "exploding tower base" in this discussion.
> The term "exploding" was probably not correct. As several others have
> phrased it, an instant expansion of steam is more correct. Concrete is
> never totally "dry" in the context of this conversation.
>
> I witnessed lightening blowing apart the two tower bases I spoke of in
> person, directly, and in real-time. It happened in the mid-sixties at the
> St. Petersburg, FL Coast Guard base. As someone else has mentioned;
> the Tampa Bay region has the highest incidence of lightening in the
> Western Hemisphere. To the one of you who accused my of lying ...
> I was there ... you weren't.
>
> At the time I was an ET aboard the USC&GS (Now NOAA) Oceanographic
> Survey ship Hydrographer/WTEI and we were in the area deliberately
> attracting lightening with balloon-hoisted cables. I -do- know something
> about the infinite uncertainty of lightning.
>
> I'm a retired electric power company two-way radio tech and have probably
> dealt with more types of towers than most of you. Large electric
> transmission
> line towers are almost always set on four concrete piers, and are grounded
> with (usually) copper straps cad-welded to each tower leg and connected to
> ground rods a bit away from the cement. Each of us can search long enough
> to find "facts" that support our various positons, especially on today's
> Internet.
>
> Here in the mountains of the West ... as well other regions ... finding and
> maintaining a "good" ground at a radio site atop a mountain can be a
> "challenge". It's almost never done with ground rods. My power company
> employer has several hundred mountain-top microwave and/or radio sites.
> Been there, done that, as they say.
>
> One responder spoke of fitting a copper pipe with a garden hose fitting and
> "flushing" it into the ground. That works very well, and is how some of my
> 14 grounds are installed. It helps if the downward end is partly
> flattened, BTW.
>
> A much bigger problem overall than lightening is water collecting in tower
> legs,
> especially in climates where it can rust (undetected) from the inside and /
> or
> freeze and split one or more legs. There's an accepted way to avoid this.
>
> 73!
>
> Ken Kopp - K0PP
>
>
> On Apr 18, 2017 at 4:30 PM, <[hidden email]> wrote:
>
>> some 40 years ago, maybe longer I put up a 50' rohn 25G tower. Dug the
>> hole
>
> and set the tower base in it alone with a 12' 3/4" ground rod and
> poured the
> cement, left about 6" of ground rod protruding. I bonded to that rod
> and grounded
> the tower. 3 years later I had a huge lightning strike on my tower and
> yes.. it cracked
> that base.
>
> never again
>
> Ronnie W5SUM
>
>> ______________________________________________________________
>>
>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

David Gilbert

Re: OT: Ground rods and concrete

In reply to this post by Rick Dettinger-3

Everyone seems tired of this thread by now, so I'll make my final
comment an observation that there is zero exposed rebar in the picture
of that guy wire base that supposedly exploded because of it. I'd offer
the possibility that the base exploded because there wasn't enough
rebar, not because there was too much. The article itself makes the
statement that faulty Ufer installations are the problem, not Ufer
grounds per se.

Dave Ab7E

On 4/18/2017 8:01 AM, Rick Dettinger wrote:
> Here is an article that described a Ufer ground failure that prompted the installation of an extensive external grounding system on a 1900’ BC tower.
>
> http://www.radioworld.com/headlines/0045/proper-grounding-and-bonding-are-crucial/338510
>
> The Broadcast industry doesn’t seem to put their faith in Uber grounding.
>
> Rick
>
>> On

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]