# Ufer Grounds Blowing up Concrete



## wendon (Sep 27, 2010)

I was working with a concrete contractor today and he informed me that he has heard that people have had their concrete footings actually blow apart as a result of a lightning strike on a Ufer ground. Has anyone ever heard of this or is it an urban legend??


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## Cletis (Aug 20, 2010)

*yes*

I heard this first hand of in my town. It's when they don't use the right amount of rebar to dissapate the lightning strike I hear


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## Wirenuting (Sep 12, 2010)

Cletis said:


> I heard this first hand of in my town. It's when they don't use the right amount of rebar to dissapate the lightning strike I hear


^x2^

And if its fresh concrete or extremely saturated soil. 

About a year ago there was a thread saying why a Ufer was bad news on old construction. I believe the argument was the possibility of to little rebar and the tie wires not being in place.

Oh ya, some ok concrete had asbestos as an added hardener. We have a few buildings here like that. Don't know I it would hurt a Ufer, just an extra thought.


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## Cletis (Aug 20, 2010)

It is a common misconception to think that a lightning
strike will blow up a concrete pad. However, consider
first, a *myth-perpetuating case of an improperly
designed system* where the tower leg "J"-bolts are
imbedded directly into the concrete pad. In this case,
due to the poor nature of the tower ground system, each
of these J-bolts will actually share a significant
amount of strike current which in turn will flow
through the concrete. Since the surface area interface
between the J-bolts and the concrete is small, the
*surge current density is very large.* The corresponding
heat generated by the energy transfer can turn the
concrete moisture into steam and possibly crack the
pad. We have only seen this happen once on a mountain
top in the Nevada desert. However, a few poorly
implemented occurrences can give a valuable technique a
bad reputation.

Now, consider a *proper implementation* of a Ufer ground
system as shown in the accompanying sketches. If,
during construction, you *incorporate all of the rebar
in the concrete pad as an integral part of your ground*
system the overall surge current density will be
*several orders of magnitude lower* than the
myth-perpetuating case above. With the *surge current
distributed over all of the rebar* there will be little
to no opportunity to develop the temperatures necessary
to vaporize the imbedded moisture. Thus, the pad will
not crack.

To successfully implement a Ufer ground system it is
*necessary to bond each of the independent pieces of
rebar together.* This is best accomplished using an
exothermic process. *Failure* to bond all elements of
rebar could allow for a *spark gap *between the
unconnected elements and thus an opportunity for
*localized heating *of the imbedded moisture. The
electrically unified rebar is connected to the tower
leg with a pigtail as shown in the sketches. The
subsurface radial lines, used with ground rods to
further dissipate the strike energy, are also bonded to
the rebar as shown. The Ufer ground is enhanced by the
fact that the local earth resistance will be lower due
to the leaching of the concrete pH into the earth which
in turn lowers its impedance. The better the ground
system, the more current flows through the tower leg
into the Ufer ground. Also, since the strike charge is
all of the same polarity, it naturally wants to spread
out. With the large surface area of the rebar closer to
the earth surface than the tower J-bolts, the current
passes easily through the concrete to get to earth
where it continues to spread out even further.

As well as the Uferground works, it should not be used
alone. We always recommend that radials or radials with
ground rods be used as the main ground system and that
the Ufer ground be used to further reduce the ground
resistance of your system. Many tests have been done,
dating back to 1968, which prove that the Ufer is a
safe and very effective way of augmenting a ground
system. For more information on Ufer grounding, see
Chapter 2 of the newly updated and soon to be published
"The Grounds for Lightning & EMP Protection."
In 1980, the National Electric Code incorporated the
use of a Ufer ground (called encapsulated ground) as
part of the code requirements for a residential house
safety ground. It is primarily used for ground fault
protection. In this usage there is actually more energy
than in a lightning strike due to the comparatively
long delay involved in waiting for the circuit breaker
to trip.


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## Amish Electrician (Jan 2, 2010)

A wee bit of history is in order.

We have the Ufer in the NEC because Max McComb, a Reno EC, used it for ski resorts in the Sierra Nevada and documented the lightning performance of this method.

Think about it: Ski lifts exist to take folks to mountain tops, and are made of steel. Can't have a better lightning target than that. So, his towers took lots of hits, and he was able to compare the UFER to every other grounding method.

Results? The Ufer did far better than everything else. It took more hits with less damage. It survived just fine.

If a lightning hit resuls in damage to the concrete around the Ufer, that strike would have done far more harm had another method been used.

Noe also that both Max's work, and that of Ufer himself, used rebar that was connected using only the usual tie wires. The NEC recognizes this. There in no need to weld the rebar together.


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## Pete m. (Nov 19, 2011)

Cletis said:


> In 1980, the National Electric Code incorporated the
> use of a Ufer ground (called encapsulated ground) as
> part of the code requirements for a residential house
> safety ground.* It is primarily used for ground fault
> ...


Really????

Then I guess the statement above negates this:

*(5) Effective Ground-Fault Current Path.* Electrical equipment and wiring and other electrically conductive material
likely to become energized shall be installed in a manner that
creates a low-impedance circuit facilitating the operation of
the overcurrent device or ground detector for high-impedance
grounded systems. It shall be capable of safely carrying the
maximum ground-fault current likely to be imposed on it from
any point on the wiring system where a ground fault may
occur to the electrical supply source. *The earth shall not be
considered as an effective ground-fault current path.*

Who authored the opinion you posted Cletis?

Pete


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## ampman (Apr 2, 2009)

wendon said:


> I was working with a concrete contractor today and he informed me that he has heard that people have had their concrete footings actually blow apart as a result of a lightning strike on a Ufer ground. Has anyone ever heard of this or is it an urban legend??


i have seen it, plus blow out the water line,through metal roofs,radio ant. on trucks,blow out tires on trucks and leave a big hole in the concrete.one time it hit a m/v pole light and when i pulled the conductors out of the conduit i had three bare stranded # 12s and three pcs. of insulation


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## drsparky (Nov 13, 2008)

Cletis said:


> It is a common misconception to think that a lightning
> strike will blow up a concrete pad. However, consider
> first, a *myth-perpetuating case of an improperly
> designed system* where the tower leg "J"-bolts are
> ...


You can't just cut and past others work as your own. This is Polyphaser Engineering Information taken directly from their site. Plagiarism at its lowest.


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## BBQ (Nov 16, 2010)

drsparky said:


> You can't just cut and past others work as your own. This is Polyphaser Engineering Information taken directly from their site. Plagiarism at its lowest.


It is Cletis, what else would we expect


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## Awg-Dawg (Jan 23, 2007)

drsparky said:


> You can't just cut and past others work as your own. This is Polyphaser Engineering Information taken directly from their site. Plagiarism at its lowest.


 
I am shocked at your accusation.:jester:


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## 480sparky (Sep 20, 2007)

drsparky said:


> You can't just cut and past others work as your own. This is Polyphaser Engineering Information taken directly from their site. Plagiarism at its lowest.



There's plagiarism, and then there's Fair Use. If Cletis were to properly give credit to the author, as he should.....then that's fine.


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## BBQ (Nov 16, 2010)

480sparky said:


> There's plagiarism, and then there's Fair Use. If Cletis were to properly give credit to the author, as he should.....then that's fine.


No chit, but he did not.


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## chicken steve (Mar 22, 2011)

according to Pete (who actually read it) it's not worth a_ chit_ anyways...

~CS~


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## Cletis (Aug 20, 2010)

*author*



480sparky said:


> There's plagiarism, and then there's Fair Use. If Cletis were to properly give credit to the author, as he should.....then that's fine.


These guys http://www.wb4hfn.com/DRAKE/DrakePageHome.htm

There was no author attatched to article so how was I to give credit?


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## Cletis (Aug 20, 2010)

Pete m. said:


> Really????
> 
> Then I guess the statement above negates this:
> 
> ...


Here, give him a shout and debate it 

[email protected]


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## drsparky (Nov 13, 2008)

Cletis said:


> These guys http://www.wb4hfn.com/DRAKE/DrakePageHome.htm
> 
> There was no author attatched to article so how was I to give credit?


Referencing the source that you got it from is better than pretending it is your own thoughts.


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## Cletis (Aug 20, 2010)

"The secret to creativity is knowing how to hide your sources."

Cletis


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## jimmy21 (Mar 31, 2012)

drsparky said:


> Referencing the source that you got it from is better than pretending it is your own thoughts.


I didn't for a second think he wrote it and I didn't think he was trying to pass of as writing it.


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## wendon (Sep 27, 2010)

So is the jury out on Ufer? Are ufer Ufer?:laughing::laughing: Maybe we should have a poll?
Personally, I like them for the sole reason that I don't have to drive rods and string the wire.


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## Pete m. (Nov 19, 2011)

Cletis said:


> Here, give him a shout and debate it
> 
> [email protected]


Nah... I'll just stick to what the rest of the nation accepts as a sound earthing method.

Pete


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## Chris1971 (Dec 27, 2010)

Amish Electrician said:


> A wee bit of history is in order. We have the Ufer in the NEC because Max McComb, a Reno EC, used it for ski resorts in the Sierra Nevada and documented the lightning performance of this method.Think about it: Ski lifts exist to take folks to mountain tops, and are made of steel. Can't have a better lightning target than that. So, his towers took lots of hits, and he was able to compare the UFER to every other grounding method. Results? The Ufer did far better than everything else. It took more hits with less damage. It survived just fine.
> 
> If a lightning hit resuls in damage to the concrete around the Ufer, that strike would have done far more harm had another method been used.
> 
> Noe also that both Max's work, and that of Ufer himself, used rebar that was connected using only the usual tie wires. The NEC recognizes this. There in no need to weld the rebar together.


Not sure where you got your information from but, here's what I came up with a simple google search.

http://en.wikipedia.org/wiki/Ufer_ground


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## Amish Electrician (Jan 2, 2010)

So someone wants to play the "source' card? .... silly wabbit ....

I grew up in a house that had folks visit, folks with names like Ufer and Soares and Steiner. I can honestly say I met them, in person. Need I say more? I had front-row seating to some of the issues we still tussle over.

Ufer did his work in the 40's. The NEC did not accept the method until Max presented the NFPA with his ski-lift data in the early 60's. That's 20 years where the method was proven, but not allowed by the NEC. Without Max McComb, there would be no acceptance of the Ufer today. Max is the forgotten hero of this method.

BTW, only in the 90's did UL revisit the issue, and re-examine the original
grounds Ufer installed. In a general study of all grounding methods, the Ufer was the ONLY one to pass the test of time. 

I never met Max, but I did meet his son. Working in Reno, I had the opportunity to follow behind him many times. I may not know him, but I know his work


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## McClary’s Electrical (Feb 21, 2009)

Amish Electrician said:


> So someone wants to play the "source' card? .... silly wabbit ....
> 
> I grew up in a house that had folks visit, folks with names like Ufer and Soares and Steiner. I can honestly say I met them, in person. Need I say more? I had front-row seating to some of the issues we still tussle over.
> 
> ...


 Man your head is way more swollen than I thought


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## Chris1971 (Dec 27, 2010)

mcclary's electrical said:


> Man your head is way more swollen than I thought


:thumbup::laughing:


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## jimmy21 (Mar 31, 2012)

It says on the wiki that a lightning strike causes moisture to turn to steam and concrete doesn't much like this


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## Amish Electrician (Jan 2, 2010)

Swollen head? No, just the facts. 

Though, I understand 'swollen head' to refer to pride - and I thought I was pretty clear in giving Max his much forgotten credit.

I can't think of much anything that likes getting hit by lightning. Can't deny Max his records, and his proof that the Ufer takes lightning better than any other electrode.

How many of your ground electrodes have taken direct lightning strikes? Max's ski lifts have taken hundreds ..... that's where he got the data that convinced the NFPA that the Ufer was reliable. "Might" is but a daydream; Max had solid data.

I suppose someone will now claim that Max's Sierra Nevada lightning was somehow less potent that their lightning. :whistling2:


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## Cletis (Aug 20, 2010)

Pete m. said:


> Nah... I'll just stick to what the rest of the nation accepts as a sound earthing method.
> 
> Pete


There was a time not too long ago when "the rest of the nation" thought the world was flat except a few


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## Big John (May 23, 2010)

Amish Electrician said:


> So someone wants to play the "source' card? .... silly wabbit ....
> 
> I grew up in a house that had folks visit, folks with names like Ufer and Soares and Steiner. I can honestly say I met them, in person. Need I say more? I had front-row seating to some of the issues we still tussle over.
> 
> ...


 So, is this a long-winded, needlessly condescending way of admitting you don't have a source?

-John


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## denny3992 (Jul 12, 2010)

How do they do groundin on islands like oahu and hawaii? Ive seen 30' that screw together... What about on volcanic rock?


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## Amish Electrician (Jan 2, 2010)

No, Big John, that was a very nice way of pointing out that *I *am the source, having been there at the time. All other "sources" come back to me, or the other folks who were there. You might as well ask Neil Armstrong to quote his 'source' on what it feels like to walk on the moon.

(Don't worry, I don't stand on ceremony. Just address me as "Your Glorious Magnificence" and all will be well  )

One can't have a better sorce on Ufer and Soares than the men themselves.

Simple review of code history will revela the late inclusion of the Ufer as an approved grounding method. Looking at the proposal you will find Max's data, as presented to the code panel. 

The more recent UL (and others) study of existing grounding methods requires a bit more digging ... but, heck, your UL rep ought to be able to get you a copy. It's a fascinating read - quite a few assumptions were dethroned.


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## Fibes (Feb 18, 2010)

Cletis said:


> "The secret to creativity is knowing how to hide your sources."
> 
> Cletis


Fetus, if anything actually intelegent is included in one of your posts most here know it wasn't a creative thought of yours


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## Pete m. (Nov 19, 2011)

Cletis said:


> There was a time not too long ago when "the rest of the nation" thought the world was flat except a few


And after a while the "flat-landers" were proven incorrect. 

If the opinion expressed here is correct in that the ufer ground is intended to facilitate the operation of an OCPD then the author should have no trouble in substantiating a proposal for a code change.

Until that happens I'll just stick with "the rest of the nation."

Pete


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