Elecraft

OT: Groond rods and concrete

Classic

List

Threaded

32 messages Options

Rose

OT: Groond rods and concrete

-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

On Mon, Apr 17, 2017 at 3:06 PM, Matt Zilmer <[hidden email]> wrote:

> Most house grounds are just a piece of re-bar hammered into the soil,
> andthis is done before the foundation is poured around it. Ours is barely
> visible except for the big chair clamp that secures the bare #8 wire to it.
> I've seen it other ways too, for example in the upper midwest. The ground
> we had in Iowa was three copper-plated rods within about one square foot,
> all bonded together. Not sure why anyone would do that, but the builder
> did the same for all houses in that development.
>
> 73,
>
> matt W6NIA
>
>
> On 4/17/2017 2:00 PM, ab2tc wrote:
>
>> Hi,
>>
>> This is totally off topic; I apologize.
>>
>> I just received the new ARRL publication "grounding and bonding for the
>> radio amateur". It is very interesting reading. I see that the NEC
>> requires
>> two ground rods for regular power installations; never mind any antennas.
>> I
>> swear that when when I moved into this house there were absolutely no
>> ground
>> rods installed. I just inspected our power pole that supplies our power. I
>> could see no wires going in to the ground. So I have no idea where our
>> "green wire" came from.
>>
>> But I have have installed two 8 foot ground rods to ground my antennas and
>> they are bonded to the AC entry panel. But what's up with this? I bet my
>> neighbors have no ground rods installed either.
>>
>> Knut - AB2TC
>>
>>
>>
>> --
>> View this message in context: http://elecraft.365791.n2.nabb
>> le.com/OT-electrical-safety-tp7629429.html
>> Sent from the Elecraft mailing list archive at Nabble.com.
>> ______________________________________________________________
>> 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]
>

______________________________________________________________
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]

Wes Stewart-2

Re: OT: Groond rods and concrete

Isn't the tower base pretty much a ground rod?

On 4/17/2017 2:16 PM, Rose wrote:
> -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
>

______________________________________________________________
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: Groond rods and concrete

No, unless adequate steps are taken to assure a large ground grid is made. This requires more than just a slab.

73,
Bill
K9YEQ

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Wes Stewart
Sent: Monday, April 17, 2017 5:17 PM
To: [hidden email]
Subject: Re: [Elecraft] OT: Groond rods and concrete

Isn't the tower base pretty much a ground rod?

On 4/17/2017 2:16 PM, Rose wrote:
> -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
>

______________________________________________________________
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]

EricJ-2

Re: OT: Groond rods and concrete

In reply to this post by Wes Stewart-2

That would make it tough to get a self-supported tower permitted in Los Angeles County and probably a lot of other jurisdictions. It wouldn't get past the engineering review.

Eric

KE6US

On 4/17/2017 3:16 PM, Wes Stewart wrote:
Isn't the tower base pretty much a ground rod?

On 4/17/2017 2:16 PM, Rose wrote:
-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

______________________________________________________________
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]<mailto:[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]

Don Wilhelm

Re: OT: Groond rods and concrete

In reply to this post by Bill K9YEQ

Good information on grounding and lightning protection for the Amateur
Radio Station can be found in the writings of Ron Block NR2B. He
published a series in QST for June, July and August of 2002.

Those articles can be downloaded from his website at
http://wrblock.com/StationProtection/StationProtection.html

This information is what I based my grounding system on.

73,
Don W3FPR

On 4/17/2017 6:25 PM, Bill Johnson wrote:
> No, unless adequate steps are taken to assure a large ground grid is made. This requires more than just a slab.
______________________________________________________________
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: Groond rods and concrete

Good article with excellent grounding theory included. Personally, I remove my equipment from the antenna system remotely during bad weather and generally when not operating, via a remote antenna switch, which I forgot to mention. When storms are eminent, I disconnect remotely and allow the discharge devices to handle static issues without the rigs connected to the antennas. No losses to date.... I also have homeowners insurance just in case the really big bolt, mother of all, should strike.

73,
Bill
K9YEQ

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Don Wilhelm
Sent: Monday, April 17, 2017 5:43 PM
To: [hidden email]
Subject: Re: [Elecraft] OT: Groond rods and concrete

Good information on grounding and lightning protection for the Amateur Radio Station can be found in the writings of Ron Block NR2B. He published a series in QST for June, July and August of 2002.

Those articles can be downloaded from his website at http://wrblock.com/StationProtection/StationProtection.html

This information is what I based my grounding system on.

73,
Don W3FPR

On 4/17/2017 6:25 PM, Bill Johnson wrote:
> No, unless adequate steps are taken to assure a large ground grid is made. This requires more than just a slab.
______________________________________________________________
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]

Wes Stewart-2

Re: OT: Groond rods and concrete

In reply to this post by Bill K9YEQ

Clearly, you have something in mind different from me.

https://www.tessco.com/products/displayProductInfo.do?sku=12952

Tell me how you avoid the exploding concrete myth using something like this?

Or with a bolted base plate:

https://www.cableandwireshop.com/rohn-45g-tower-concrete-base-plate-r-bpc45g.html

Read the last sentence.

On 4/17/2017 3:25 PM, Bill Johnson wrote:

> No, unless adequate steps are taken to assure a large ground grid is made. This requires more than just a slab.
>
> 73,
> Bill
> K9YEQ
>
> -----Original Message-----
> From: Elecraft [mailto:[hidden email]] On Behalf Of Wes Stewart
> Sent: Monday, April 17, 2017 5:17 PM
> To: [hidden email]
> Subject: Re: [Elecraft] OT: Groond rods and concrete
>
> Isn't the tower base pretty much a ground rod?
>
> On 4/17/2017 2:16 PM, Rose wrote:
>> -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
>>
> ______________________________________________________________
> 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]
>

Doug Renwick

Re: OT: Ground rods and concrete

In reply to this post by Rose

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]

Rick Dettinger-3

Re: OT: Ground rods and concrete

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]

David Gilbert

Re: OT: Ground rods and concrete

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]

Richard Fjeld-2

Re: OT: Ground rods and concrete

In reply to this post by Doug Renwick

Just a comment on myth controversy when dealing with Lightning and
grounding topics.

I know guys that are doing all the wrong things with their practices.
They can't be persuaded otherwise.
Yet, the odds have favored them for years. That reinforces their
thinking that they are right and logic is wrong.
But I have seen what has happened to others.

Lightning strikes are one hazard. Static energy build up on antenna
systems is another. Both can destroy.
And, then there is the lightning type potential coming in on the AC
power line to consider.

Dick, n0ce

On 4/17/2017 10:32 PM, Doug Renwick 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
>
>
>
______________________________________________________________
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

In reply to this post by David Gilbert

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]

David Gilbert

Re: 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]
>

Ted Edwards W3TB

Re: OT: Groond rods and concrete

In reply to this post by Wes Stewart-2

The first time I put up a tower I just put the ground rods down from the
bottom of the hole and brought the connecting wire up through the
concrete. No problems happened, but maybe I just got lucky. Nobody had
ever said anything to me to the contrary.

For radio grounding to earth, I use 1/2 inch copper pipe 10 foot length and
get it in the ground hydrolically with a fitting that lets me put the
garden hose to the end and shoot water from the other end to make the
hole. Works really well. And I have wondered whether to connect another
10 feet and go deeper. I have 5 of those connected together in common.

On Mon, Apr 17, 2017 at 8:25 PM, Walter Underwood <[hidden email]>
wrote:

> House grounds and tower grounds are designed for different hazards (and
> risks, which are hazards with dollars).
>
> Direct lighting strikes on houses are less common than power line surges.
> So house grounds are designed for surges, which can be large. A direct
> strike on a stucco house is going to vaporize the wire mesh and blow the
> stucco off in several places. Ground rods won’t help that much.
>
> A tower is much more likely to get a direct strike. The grounding system
> on a tower is designed to survive a feeder strike and reduce the
> destruction (risk) of a direct strike. Better to melt the coax than burn
> down the transmitter shack.
>
> When I was in high school in Indianapolis, my next door neighbor was a ham
> with a tower. He had worked on lighting arrestors at GE. He explained that
> a lighting pulse had so much high-frequency energy that it more followed
> than conducted along a ground strap. It jumps from the strap to the
> building and back about every two feet. Lightning systems are a hint, not a
> directive. Nobody tells lightning what to do.
>
> I like what I do, but working on lighting arrestors? That would be COOL.
>
> wunder
> K6WRU
> Walter Underwood
> CM87wj
> http://observer.wunderwood.org/ (my blog)
>
> > On Apr 17, 2017, at 4:16 PM, Wes Stewart <[hidden email]> wrote:
> >
> > Clearly, you have something in mind different from me.
> >
> > https://www.tessco.com/products/displayProductInfo.do?sku=12952
> >
> > Tell me how you avoid the exploding concrete myth using something like
> this?
> >
> > Or with a bolted base plate:
> >
> > https://www.cableandwireshop.com/rohn-45g-tower-concrete-
> base-plate-r-bpc45g.html
> >
> > Read the last sentence.
> >
> >
> > On 4/17/2017 3:25 PM, Bill Johnson wrote:
> >> No, unless adequate steps are taken to assure a large ground grid is
> made. This requires more than just a slab.
> >>
> >> 73,
> >> Bill
> >> K9YEQ
> >>
> >> -----Original Message-----
> >> From: Elecraft [mailto:[hidden email]] On Behalf Of
> Wes Stewart
> >> Sent: Monday, April 17, 2017 5:17 PM
> >> To: [hidden email]
> >> Subject: Re: [Elecraft] OT: Groond rods and concrete
> >>
> >> Isn't the tower base pretty much a ground rod?
> >>
> >> On 4/17/2017 2:16 PM, Rose wrote:
> >>> -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
> >>>
> >> ______________________________________________________________
> >> 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]
>

--
73 de Ted Edwards, W3TB and GØPWW

and thinking about operating CW:
"Do today what others won't,
so you can do tomorrow what others can't."
______________________________________________________________
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

In reply to this post by David Gilbert

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 Apr 18, 2017, at 12:25 AM, David Gilbert <[hidden email]> wrote:
>
>
> 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

Re: OT: Ground rods and concrete

In reply to this post by David Gilbert

Dave is correct, just read a little on CEE or Ufer grounds, perhaps
the idea of exploding bases comes
from a statement about Ufer grounds,

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.^

^"Electrical Overstress/Electrostatic Discharge Symposium Volume 22" By
ESD Association, Institute of Electrical and Electronics Engineers"

73 Merv K9FD/KH6

>
> 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]

Wes Stewart-2

Re: OT: Ground rods and concrete

In reply to this post by Rick Dettinger-3

I don't know whether I would call that "extensive" damage but whatever...

I have my own photos of me standing next to this anchor, but since I can't send
attachments, here is a link:
https://en.wikipedia.org/wiki/KVLY-TV_mast#/media/File:KVLYPylon.jpeg

I didn't see any extra grounding conductors. BTW, my GPS said this was 1/4 mile
from the base of the tower :-)

I'm not saying that extra grounding isn't required or is a bad idea, just that
concrete encased steel isn't a bad idea.

Wes N7WS

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 Apr 18, 2017, at 12:25 AM, David Gilbert <[hidden email]> wrote:
>>
>>
>> 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
>>>>>
>>>>>

Guy Olinger K2AV

Re: OT: Ground rods and concrete

In reply to this post by Doug Renwick

Part of the mental imaging problem here is that our brains, in their
internal emotional response to orders of magnitude, simply cannot scale the
destructive power in lightning. Lightning is quite capable of melting the
leads to six properly done ground rods, AND at the same time blowing up a
perfectly done to code concrete base with reinforcing rods.

It just needs to be a big enough strike. I would guess (zero proof, just a
nagging inclination) that the odds of this are considerably reduced by the
presence of decently tall trees in the immediate vicinity (another loooong
discussion).

Anyone who has seen a lightning strike turn three or four cubic yards of
ground dirt into glass in milliseconds, or seen a huge strike on a lake
surface boil water within a 10 foot radius has a good gut based lightning
strike power scaling device.

Every now and then I will get on YouTube and watch the cellphone videos of
the 2011 Japanese Tsunami to remind myself of the absolutely enormous
kinetic energy in a twenty foot high wall of water moving at 20 miles per
hour.

Nature can completely blast any one of us to smithereens if it wants to.
Thankfully that is nowhere near norm.

The question is how much moolah do you want to lay down, how many otherwise
good solutions do you want to shelve, for a rarity? Like how to invest,
that is a very personal decision. Good luck to all.

73, Guy K2AV

On Mon, Apr 17, 2017 at 11:32 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]
>

Jim Brown-10

Re: OT: Ground rods and concrete

In reply to this post by Wes Stewart-2

I'm with you, Wes. And I strongly agree with AB7E's excellent post.

The cited article does NOT say that "The Broadcast industry doesn’t seem
to put their faith in Uber grounding." It DOES say that a Ufer ground
done improperly can be a problem structurally. Notice also that the
author "is national program manager for Copper Development Association
Inc." I see nothing in the way of engineering credentials. The author
quotes extensive advice from "a power quality expert, Martin Conroy,"
again with no credentials given. That said, Conroy's advice is pretty
good, and is mostly in agreement with good engineering practice. He did
not say that the Ufer ground was a bad idea, but he did recommend
supplementing it with deep rods around the tower, spaced radially out
from the tower, and a buried ground ring, all robustly bonded together
and to the tower.

If you read the new ARRL book on Grounding and Bonding (by N0AX), you
will see a recommendation for a Ufer ground within the tower base,
bonded to the tower, and to multiple ground rods around the tower base,
spaced at least a rod length from the tower and from each other. If the
tower is close to the building, it calls for bonding between the tower
ground system and the building ground. If the tower is more than 60-100
ft from the building, bonding is NOT recommended (or useful) because
that bonding conductor (and the coax shield) have too much inductance to
be a low impedance at RF.

I was one of several engineers who Ward consulted for peer review, and
much of the book parallels my tutorial on Grounding and Bonding for ham
radio.

73, Jim K9YC

On Tue,4/18/2017 10:35 AM, Wes Stewart wrote:

> I don't know whether I would call that "extensive" damage but whatever...
>
> I have my own photos of me standing next to this anchor, but since I
> can't send attachments, here is a link:
> https://en.wikipedia.org/wiki/KVLY-TV_mast#/media/File:KVLYPylon.jpeg
>
> I didn't see any extra grounding conductors. BTW, my GPS said this
> was 1/4 mile from the base of the tower :-)
>
> I'm not saying that extra grounding isn't required or is a bad idea,
> just that concrete encased steel isn't a bad idea.
>
> Wes N7WS
>
> 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.

Doug Person-4

Re: OT: Ground rods and concrete

In reply to this post by Guy Olinger K2AV

Working on a fire line in a national forest I've seen 75 foot pine trees
that had been completely exploded from a lightening strike. The sap
reaches boiling point in an instant and burning parts of the tree gets
distributed over the ground which leads to a fire crew being dispatched.
Most wildland fires in these parts are due to lightening and ocurr 5-10
times per year.

My own antenna system has never had a direct strike despite the high
lightening activity here in the high Rockies (8200'+). But several
times surges have blown the fuses on my lightening protectors. One near
strike even got past that and destroyed my switch box - which was also
fused.

K0DXV

On 4/18/2017 11:41 AM, Guy Olinger K2AV wrote:

> Part of the mental imaging problem here is that our brains, in their
> internal emotional response to orders of magnitude, simply cannot scale the
> destructive power in lightning. Lightning is quite capable of melting the
> leads to six properly done ground rods, AND at the same time blowing up a
> perfectly done to code concrete base with reinforcing rods.
>
> It just needs to be a big enough strike. I would guess (zero proof, just a
> nagging inclination) that the odds of this are considerably reduced by the
> presence of decently tall trees in the immediate vicinity (another loooong
> discussion).
>
> Anyone who has seen a lightning strike turn three or four cubic yards of
> ground dirt into glass in milliseconds, or seen a huge strike on a lake
> surface boil water within a 10 foot radius has a good gut based lightning
> strike power scaling device.
>
> Every now and then I will get on YouTube and watch the cellphone videos of
> the 2011 Japanese Tsunami to remind myself of the absolutely enormous
> kinetic energy in a twenty foot high wall of water moving at 20 miles per
> hour.
>
> Nature can completely blast any one of us to smithereens if it wants to.
> Thankfully that is nowhere near norm.
>
> The question is how much moolah do you want to lay down, how many otherwise
> good solutions do you want to shelve, for a rarity? Like how to invest,
> that is a very personal decision. Good luck to all.
>
> 73, Guy K2AV
>
> On Mon, Apr 17, 2017 at 11:32 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]