[Elecraft] OT: Ground rods and concrete

[Merv Schweigert]

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 <ve5ra at sasktel.net> 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
>>>
>>>
>>>
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