Some of the BOs in this area have allowed the rebar to be turned up in the wall and the GEC connection to be made there instead of in the footer. I would like to know if any other jurisdictions allow this and what if any proplems you have encountered. What are your thoughts?

The turned up rebar is not a UFER. There have been many discussions on this board that say this.



ps - Footer is slang; it's footing.

I did search the topics but did not find much. Might have done it wrong. I always thought this connection was required to be made in the footing. Sometimes this rebar gets cutt off or left out completely. Just wondering how everyone else does it.




ps - we like slang up here.

Well the slang for the up turned rebar is a 7 iron.
It was allowed years ago in Pinellas county.
Here are my thoughts.
First the rebar does not have any corrosion protection.
It is designed to be encased in concrete.
If it is then the rebar will hold up.
If exposed then corrosion will eat up the rebar and start its way into the slang(footer). When rebar rusts it expands which can result in cracking the concrete.
In one area in pinellas even the zinc coated ground rods rusted away at grade level within a few years. For whatever reason.

Now back to the slang(7 iron).
It usually is a short piece of rebar with a 90 degree bend hence the name.
Tie wired to the normal slang(footer) rebar which is 20 foot long.
So going back to 250.52 it must be 20 foot long with out tie wire.
Located near the bottom of the slang(footer)
Be of at least 1/2" diameter.

So even if you use a full stick of rebar. bend a 90 on the end of the rebar in the concrete, It will at best be around 18 to 19 feet long.

The part about tie wires at the end of the article in my opinion refers to bonding to the rest of the slang(footer) rebar in the rest of the slang(footer).

My 2 cents.

So what you are saying is that technically, the connection to the doohickey needs to be at the bottom of the footer, in order to be a true concrete cased electrode.

I never liked the rebar-sticking-out method that was used in Pinellas for years, because as Ruben mentions the rebar is left exposed and corrodes, and so does the connection. Sometimes the rebar was even stubbed below grade. From experience I can say that the connections were frequently loose, and the gardener was somehow magnetically drawn to this connection point, which would get knocked into by his shovel or weedwacker, I never knew which. Or maybe it was the dreaded sprinkler guy (they have some real neat wiring methods, too).

Then others - partially agreeing with this logic - invented a new method - turn up the rebar into an interior wall and make the connection there. Ok fine, but...is that really 20' of rebar near the bottom of a concrete footing? Or is that a splice? Did anyone check the steel twisty-ties to see if they were tight? Is the 90 even connected to the footing? Or did the steel guy just "conveniently" stick it in the right spot, without even splicing it? If there was a splice, did it have proper lap? Did someone even check for lap? Has this method even been tested? (Don't laugh in Poke County to this day, some stick the 90's in after the slab is poured, breaking about every code in the book)

So after a decade or more of reinventing ways to confuse and confound the simple and pure, unadulterated, concrete encased electrode, the truth of the matter is that the connection to the doohickey needs to be at the bottom of the concrete footer, in order to be a true concrete cased electrode.......and sorry John I thought there was a post on this, my mistake.

doohickey,Whatchamacallit, all the same.

It is the way they have been doing it in Lee county and still are as far as I know.
They do use a whole stick but fall back on the idea that there is plenty of total length and the 7 iron "shall be permitted to be bonded together <with the rest of the steel> by the usual steel tie wires or other effective means".
The corrosion issue is considered minimal since this comes up inside the envelope of the house.

From a couple years ago
http://gfretwell.com/electrical/ufer.jpg

I really don't have a dog in this fight but when the contractor told me a 4ga copper wire sticking out of the footer would have a street life of about 3 days (or nights) I thought he might have a point.

We do allow the rebar to be turned up inside the wall, using a 20ft piece of rebar(7iron) and securely tied to the footer rebar, verified by electrical inspector before the building inspector passes the footer inspection

Looking at the situation purely from an electrical standpoint, it really doesn't make any real difference. As long as the prescriptive requirements of 250.42(A)(3) are met, the actual orientation of the rebar and where the GEC connects will not functionaly change its performance.

That being said, I agree that the electrode itself should be encased, thus the GEC conection and a portion of the GEC should also be encased. If the rebar leaves its encasement its no longer an electrode and it doesn't qualify as a GEC.

I feel one solution would be to allow a vertical portion of the rebar to serve as the connection point if that rebar is in a poured cell. That way, the prescritive requirements of the section are met by the portion of the rebar in the horizontal footing. The short vertical section also gets encased along with the GEC connection. This is permitted by 250.68(A) Exception No. 2.

Another solution is to make the GEC conenction near the top of the slab/floor where the rebar protrudes up, cut of the rebar, and then form and pour the assembly to re-encase the whole thing.

From a structural stand-point, as long as the rebar is not being used as reinforcement, its really not under the scope of the building code. But, that still doesn't change the fact that it could pose a corrosive hazard to the concrete over time. The effect would be much less if the rebar is stubbed up in an interior wood / metal framed wall rather than an exterior masonry wall.

This is a good topic...

Why can't we do just what's in the code. Than all the other problems go away.

Sometimes it gets missed, cutt off, stubed up in an inaccessible place. I wonder if requesting a DEC Statement from FBC would clarify this requirement.



Now, Never heard it called a 7-Iron. I have a 7-Iron manufactured by Cleveland and is good for about 150 yards on a good day. As far as Mr. Doohickey goes, My Mother explained to me who he was when I was very young.

Doohickey???
That's what you use to bend rigid with. LOL

getting hard to keep track of all these technical terms

Does anyone allow only a #4 bare to a concrete encased electrode to be used as the "grounding electrode system" for a 400 amp residential servce?

I hear rumor that is all some are requiring.

Neal
COTInspector

YES! A #4 GEC to a concrete encased electrode / as the CEE would be sufficient for a 2,000 amp service as well.

I have to ask some dumb questions;
Why is Table 250.66 still in the Code Book, maybe we can get Bill Pancake to get it removed if no one uses a fully sized grounding electrode system anymore?
When does a grounding electrode as described in 250.52(A) (1) through (A) (7) become present?
If the foundation is already poured when the electrical contractor arrives on the site is he now exempt from using the concrete encased electrode as part of the grounding electrode system (not present anymore right)?
If the electrician has #2 copper wire and a ground rod on his truck when he pulls up on a site, is he now required to install a ground ring and a ground rod (present right)?
If none of the electrodes exist how many of grounding electrodes specified in 250.52(A) (4) through (A) (8) are required to be installed and used, one or more?
Would it also be ok to ground a 2,000 amp service with one ground rod connected to a #6 copper grounding electrode conductor if there are no other electrodes present?
If this GES has greater than 25 ohms resistance, we can just add one additional ground rod tie the 2 rods together with a #6 and call it a properly grounded system?

I personally do not believe, especially after re-reading Chapter 6 in the Soares 10th edition several times, that a #4 GEC to a 250.52 (A) (3) electrode for any service above 200 amps, meets the performance requirements stated in 250.4.


Neal Burdick
COTInspector

Neal, you have to use what you have available and the engineers figure out how effective they are. They have decided a #6 will carry all the current a rod will sink and a #4 will carry all you get from a Ufer. 250.66 really refers to more effective electrodes like a whole city full of metal pipe. Once that got down to a minimum of 10' of pipe in contact with the soil (the rest being plastic), I imagine a #6 would do the trick there too.
We may be entering a time when there are no decent ground electrodes. In my house, I imagine the concrete pool shell is the best electrode but it is only required to be bonded to the MBJ in the panel with a couple of 12ga copper EGCs (the light and pump)

As for the Ufer being available, it should be part of the footer inspection. I know I used to look at them all the time when I was inspecting.

Table 250.66 is required to be used "except as permitted in 250.66(A) through (C). So, GEC's bonding metal underground water pipe and metal frame of the building or structure electrodes are sized to the Table. Also keep in mind that other bonding and grounding components are sized to Table 250.66 such as Equipment Bonding Jumpers on Supply Side of Service.



No. The electrode is present. This is not a code issue but a cooridnation issue. It is the responsibility of the builder to properly schedule his contractors to perform work at the appropriate time. It wouldn't make sense for a builder to install all the drywall in a structure before the electrical wiring has been installed, just as it doesn;t make sense for a builder to pour the footings prior to the CEE being installed.



Of course not. Remember, section 250.50 requires all the electrodes that are present to be BONDED together to form the GES. It is only when they do not exist at the strucutre that you are required to create / install the electrode.



YES!



YES!



Then as soon as you become a PE or electrical engineer that is free to design the grounding electrode system on your prjects in any manner you wish, we can only enforce the requirements of the code as they are written.

GOOD QUESTIONS !!!

Please don't assume that a footing that is twelve inches deep in dry sand is much of a connection to earth. I recall that E.E.'s in Saudi Arabia salt the sand and saturate it for an earth connection...I can check for continuity from a steel doorjamb in a damp basement but get no continuity above grade level...The deeper you go and the more moisture in the earth the better...Ufer, pilings, made electrodes...whatever. Biddle Instruments had an old book on grounding and part of it is incorporated into the 'Soare's' Book...It may be available online.

I still find it hard to believe that a 3/4" copper water pipe (let's say 10'6" long) in direct contact with the earth is a better electrode than a concrete encased electrode.
Does anyone know where that test data maybe found online?


Neal Burdick

http://www.artikel-software.com/file/Bonding_and_grounding.pdf
Compliments of the Pentagon...via Delhi, India...

You could look forever for data.
But just think about the surface area difference in contact with the earth.
But anyway.
Here is a article by the iaei:
http://www.iaei.org/magazine/?p=3626

Thanks you guys.
I think I'll start with the IAEI article.

Another dumb question.
If there is plastic barrier (visqueen) between the earth and the concrete encase electrode can it still be used as an electrode?



Neal

The "performance" of the grounding electrode system is all in the bonding aspects of the system. The actual grounding component does not have all that much signifigance. In order for a hazard to be present during a 250.4(A)(1) event, there must be an imposed voltage. If all the non-current carrying metal parts of the system(s), the grounded service conductor, the system EGC's, the service equipment enclousres, and the earth are all bonded together per code, there will be no voltage potential between those parts thus no current will flow for the duration of the event.

So why it is important that the earth be a component of this protection system, it is not the essential or critical aspect. The overall circuit impedance of the earthing connection are really not all that important. Clearly, a single #6 AWG conductor terminating at a single 8' ground rod is all that is really needed to perform effective grounding of the system. However, it is essential that you BOND any other electrode that is present to ensure no potential is created between the different grounded elements.

So in essence, the pupose of 250.50 is NOT an attempt to create as many grounding connections as possible, but rather to ensure that all present grounding connections are bonded together.

GET IT?

Neal, the visqueen should not be extended under the footer, only to the edge of the floor.

Bryan, I will throw more gas on the fire.
How much neutral current do you figure the earth is carrying?
I know on my street where we have wye distribution there is current on all of the transformer grounding electrode conductors going down the pole and I have a couple of amps on the drop neutral coming into the house with the main breaker off.
I talked to my FPL lineman neighbor about it and he didn't even grasp the concept that all of the current was not going to go down that aluminum/steel 2 gauge strand they bond to and he assumed that ground wire would assure zero volts because a foot or so of the #6 was coiled and stapled to the bottom of a pole 6-8 feet in the ground. When I started talking about voltage drop his eyes glazed over.
This particular string of 20 transformers is about a 3/4 mile long. How many volts do you figure they drop along that strand? How much do you figure the earth tries to make that up?
This does take some of the mystery out of where "stray voltage" can come from. The street behind my house is fed from another phase on the distribution and I have always wondered what the voltage difference would be between his ground electrode and mine. I certainly would not want to string a LAN cable between our houses.

I really need to be studying for my P1 exam rather then discussing something that has been some of the most unclear and poorly written code sections for over 75 years, but here I go again.

And by the way I do “Get It” as I have designed and installed many approved grounding electrode systems that are still performing as required by the NEC for over 25 years,as well as having inspected a 1,000 or so GES in the last five years.

Part of the problem here is not understanding what word “system” means. “System (noun) a group or combination of interrelated, interdependent, or interacting elements forming a collective entity; a methodical or coordinated assemblage of parts, facts, concepts.”


“250.50 Grounding Electrode System (there is that word).
All (not just one electrode but all) grounding electrodes as described in 250.52(A)(1) through (A)(7) that are present (only (A)(1), (2), (3), or (8) would be present during normal construction all other electrodes are only present if you bring them, why do they include (A)(4) – (A)(7)????) at each building or structure served shall be bonded together to form the grounding electrode system (there is that word again). Where none of these grounding electrodes exist, one or more (I choose more) of the grounding electrodes specified in 250.52(A)(4) through (A)(8) shall be installed and used.


Even the NEC handbook encourages the formation of a system of electrodes, which adds reliability and ensures performance.


“Section 250.50 introduces the important concept of a “grounding electrode system,” in which all electrodes are bonded together. Rather than total reliance on a single grounding electrode to perform its function over the life of the electrical installation, the NEC encourages the formation of a system of electrodes “that are present at each building or structure served.” No doubt, building a system of electrodes adds a level of reliability and helps ensure system performance over a long period of time.”


In the City of Tampa on a non-reviewed new construction services we encourage and get a concrete encased electrode, and two ground rods. The electrode to the CCE is sized to table 250.66 based on the service entrance conductors. For a service upgrade on an existing structure we require two ground rods, and a water connection if still metallic pipe, once again sized according to 250.66. This has been the practice in Tampa longer than the 5 years I have been there, and I believe the systems installed are meeting the “intent” of the code for the GES.


In my opinion if an electrical contractor, electrical engineer, plans examiner, electrical inspector, installed, designed, approved the plans, approved an inspection on a grounding electrode system that only had a #4 copper wire connected to a concrete encased electrode on a service with larger than 3/0 copper service conductors, rhey should look for a new career.


Well I need to go study plumbing, I’m done with this one thanks for reading.

Neal Burdick

My Opinions and Mine alone

I don't think anyone here is questioning what you know Neal, certainly not me.  I've seen the CMP-5 members themselves argue over the meaning of a section.  If they can't figure it out, no wonder we have these discussions out in the real world.The grounding electrode system is more than just the electrodes.  The system is the electrodes, the GEC, the fittings and connectors, etc.  The reason 250.50 requires ALL the electrodes that are present to be bonded is to prevent an electrode that is present from not be bonded.  So, if someone were to drive a ground rod, required or not, it is now present and must be bonded to the grounding electrode system.  Again, a designer can include as many electrodes as they wish, however the code stipulates they must all be bonded.That's great, but not enforceable.  The code is a minimum and the minimum is all that is required.Why not require two or more of everything required by the code?  That would certainly be better.  Instead of just one required lighting outlet per room, lets make it two just in case one doesn't work.  Instead of just one receptacle within 3' of a bathroom sink, let's make it two just because redundancy is better.  You can quickly see how this can get out-of-hand.I think this is an incorrect interpretation of the code.  If the city of Tampa believes this is the appropriate method of grounding for their jurisidiction, they should submit a proposal to the NFPA or the Florida Building Commission to have the rule changed.  Until then, the city really has no legal basis for requiring anything more than the code.

I agree with Neal as to what the customer should demand and what the EC should install but Bryan is right about what the AHJ can require. Perhaps it is time to get CMP-5 to look at this again. I do believe it is a waste of copper to put in a GEC that carries more current than the electrode can sink but that just means we need better electrodes. One rod driven in dry sand is not much of an electrode and another one right next to it does not improve that much. Dr Ufer's CEE is probably sufficient for most single family (typically 200a) but that gets troubling when you get into large commercial buildings with 1600a services if you believe 250.66.

Maybe we need to review what the GES does for us. We know it does not clear faults. Why is the service size important?
Are going to admit the earth really does carry circuit current?

It does clear faults. It may not be designed for that purpose, but in real life it can perform that function. Better that current return through it......than through me.

I know that up North, at least two methods of grounding were REQUIRED. Down here, no, just NEC. OK, I'm going to shut up now, I promised myself I would not even post on this subject.

You just can't resist can you?

If you are counting on the circuit through an 8' ground rod through 100 feet of sand to 10 feet of #6 stapled to a pole to clear a fault, I hope you are on a small breaker.
It sounds more like a worm chaser to me.

Back in my younger day, when I was foolish and inexperienced, I could run an entire house on the grounding electrode system (during hot check). It actually worked.

I bet, back in your younger days, the GES was a metal water piping system that spanned the city.
Now it is likely to be a Ufer at best and could just be a couple of rods that struggle to get 15 or 20 ohms to the sand. It takes a GES with less than 6 ohms to trip a 20a breaker and that won't cook off for a while. I bet a 20a bolted fault into a rod would cook off the water and increase in resistance before the breaker tripped.
Your only hope would be if your rod was in the ground water ... but then it may have corroded away in a few years.

This would be a good study for one of these university engineering departments. Send the students out with real ground performance equipment and evaluate the GES in various buildings around town. Pull some rods that have been in the ground for 10-15 years and see what you have. Inspect the clamps.

I bet, if the FBC really looked at that study we would be doing CadWelds on rods, banning steel core rods and certainly requiring something in addition to a rod or two. I know for a fact that the 15 year old clamp on the rod at this house was not working when I moved in and there was only the one rod.

You bet wrong. Back in 89 and still to this day, Pasco County did not have metal water piping systems that span anywhere. In fact, you didn't even have 10' of metal piping underground.

It was a ground rod only. Works rather well, even in sand. I bet a UFER works even better.

I am just basing my thoughts on the "ground shift" I have seen between buildings when you start stringing data cables between them. It becomes evident very quickly that "ground" is not "zero volts". That becomes particularly evident with transients and surges during lightning events.

Data cables are a bear.
Especially between buildings but you also are dealing with the internal grounding of each cable in the nic cards. Which are internal to each device which is powered by many different branch circuits.
So the impedance is different between all of the devices.

I guess that is why the IT people tried to start just driving ground rods everywhere.

Ground rods are a waste of money in these cases. Bonding is the trick. Make all the grounding electrodes in all of the buildings one big GES and you have something.
In our case (IBM) we did not have access to the service without triggering complaints by everyone from the IBEW to the electrical inspector so we bonded the machine cases with black wire and called it a "drain", a carefully chosen, ambiguous term.
One of the first places where that was done on LANs was at the old Holiday Inn in Ft Myers on the water front (3 buildings merged into one over the years). A lot of the original work was done by Sate Farm in Winter Haven. The IBM IPR guy in Tampa came up with the "drain". We built off of their work.
With various types of surge protection devices and better bonding we took a situation where we were getting several lightning damage calls a day in the summer down to a couple a year.