250.52(A)(3) Concrete-Encased Electrode

[tryinghard]

There is none, a footing may be larger or small.

This is the point I?m trying to make, and my example of a lift station structure is a 10? x 15? slab with a footing that is simply a lower beveled edge. This structure is built like a bus stop and houses our panelboard and controller for the pumps and other circuits.

Another example of a concrete structure is a switchboard placed freestanding on concrete.

But a footer or foundation has a specific function and that function is to support the weight of the building.

[and or item & structure] true but its size is engineered par application therefore the size is interpretive.

In general a slab is never used to be the support the building. Usually the ground level slab 'floats' in relation to the buildings foundation, it is often isolated by fiber board expansion material at all the edges.

In this area you will recognize a structural slab as it will be very thick and have large rebar in massive quantities in it.

That said I have hardly seen it all so I would not be surprised if there are some areas that use the slab to support the building.

You would see more in smaller construction that is a large percentage of work nationally.

 

[tryinghard]

Where I work and play, the slab has a plastic/viscine liner under the slab to provide a vapor barrier. This alone would nulify the "slab" as an effective CEE.

A slab is a slab, and footings and foundations are footings and foundations.



If the building is being built on slab, remember there is not much depth to the slab, and the contact with the earth is could be determined as not being deep enough.

The type of electrode should be predetermined before construction. If so all parties involved can expect [and inspect] correctly. The examples I have given do not include vapor barriers but if they did a CEE would not work.

I suggest your plan check process red line drawings that are not clear what type of electrode will be used. If you inspecting a job that is design build ask, ?what electrode will you be using?? and inspect accordingly, walk off if their reply is ?I?m not sure but doesn?t this steel work?? or ?isn?t this steel my ground?? If they cannot assert they did not have a qualified journeyman electrician install the electrode.

 

[iwire]

[and or item & structure] true but its size is engineered par application therefore the size is interpretive.

Again size has absolutely nothing to do with it.

You could have a slab the size of Arizona and if it does not support a building or structure it is still not a footing or foundation. :smile:

You would see more in smaller construction that is a large percentage of work nationally.

Even slab homes usually have a stem wall that is supported by a footing.

Here is a slab on grade construction detail, the slab is slab and the part heading down into the earth is a footing.

Here is another that sounds a lot like your installation.

The footing is only at the perimeter so only the rebar in the footing can count as a CEE.

Pierre spelled it out

A slab is a slab, and footings and foundations are footings and foundations

Also Pierre mentioned the vapor barrier that is often used under a slab.

It is my opinion that even without the vapor barrier under the slab that a slab, no matter how much rebar is in it will never qualify as an NEC CEE.

 

[tryinghard]

Thanks for the picture! This is the application I've been talking about in all my examples. We are saying the same thing, size of footing does not matter and this drawing reiterates this.

Again size has absolutely nothing to do with it....Here is another that sounds a lot like your installation.

The footing is only at the perimeter so only the rebar in the footing can count as a CEE.

The footing is only at the perimeter so only the [#4 cu] or rebar [within and near the bottom of the] footing can count as a CEE[, if it is encased with at least 2” of concrete.] So 1” ‘dobie’ blocks are a violation if used to support the electrode from earth, even 2” ‘dobie’ blocks are in violation if the rebar sags between supports. In fact there may not be rebar in this footing, the builder is responsable for structural not the electrician.

I am really saying either type should be installed by a journeyman electrician and not directed or delegated to a non-electrician to install. This means if an electrician chooses to use rebar the electrician should furnish and install this electrode to 250.52(A)(3), I will simply use the #4 cu.

 

[crossman]

So even if it is only a slab, and even if there are vapor barriers, there is still nothing that prohibits me from connecting the rebar to the GEC. Yes, I still need to comply with 250 concerning the actual Grounding Electrode System and all the other available and required "made electrodes". But you can tie to the reinforcing steel all day long no matter what the situation.

 

[iwire]

So even if it is only a slab, and even if there are vapor barriers, there is still nothing that prohibits me from connecting the rebar to the GEC.

I agree entirely, never said otherwise. :smile:

All I was pointing out is the slab rebar would not qualify as an NEC electrode.

 

[crossman]

I agree entirely, never said otherwise. :smile:

All I was pointing out is the slab rebar would not qualify as an NEC electrode.

I know!:smile:

 

[tryinghard]

So even if it is only a slab, and even if there are vapor barriers, there is still nothing that prohibits me from connecting the rebar to the GEC. Yes, I still need to comply with 250 concerning the actual Grounding Electrode System and all the other available and required "made electrodes". But you can tie to the reinforcing steel all day long no matter what the situation.

If it is a full 20' long piece at or near the bottom, multiples wire tied together that equal 20' or more are not in compliance as an electrode.

 

[tryinghard]

I agree entirely, never said otherwise. :smile:

All I was pointing out is the slab rebar would not qualify as an NEC electrode.

Post #31,:roll:

 

[crossman]

If it is a full 20' long piece at or near the bottom, multiples wire tied together that equal 20' or more are not in compliance as an electrode.

The 20 foot length required for a CEE can most certainly be, for example, two 10 foot pieces of rebar connected together with tie wire.

As a matter of fact, twenty 1 foot pieces of rebar in the bottom of the foundation, and tied together with either tie wire or by multiple connections to a GEC would be acceptable as a grounding electrode according to the literal text of the code.

 

[crossman]

Post #31,:roll:

:roll:

Please pay attention to my point....

So even if it is only a slab, and even if there are vapor barriers, there is still nothing that prohibits me from connecting the rebar to the GEC. Yes, I still need to comply with 250 concerning the actual Grounding Electrode System and all the other available and required "made electrodes". But you can tie to the reinforcing steel all day long no matter what the situation.

The reason i said it is this: I can just see some hOmE InsPecToR or MulTi-CraFt InsPeCtOr telling an EC that it is against code to tie into the rebar because of "that rebar is too short" or "that rebar isn't in the bootom of the footing" or "that rebar is in a slab, not a foundation" or whatever.

I simply wanted to point out that there is nothing preventing me from tapping off the grounding electrode conductor and tieing it to the rebar in, for example, my 3 foot by 3 foot by 6 inch thick concrete Air conditioner condenser pad. Or any other rebar anywhere for that matter.

I also pointed out that these "extraneous" connections would not relieve us from completing the GES as per code, for example, the supplemental electrode required for a water pipe.

 

[infinity]

The 20 foot length required for a CEE can most certainly be, for example, two 10 foot pieces of rebar connected together with tie wire.

As a matter of fact, twenty 1 foot pieces of rebar in the bottom of the foundation, and tied together with either tie wire or by multiple connections to a GEC would be acceptable as a grounding electrode according to the literal text of the code.

I agree, multiple sections of #4 or larger rebar can be tied together to form the CEE, but how do you measure the required 20'? If you took 2-10' x 1/2" rebars and over lapped them by 1' and tied them the tied together your continuous piece would only be 18' in length. Does this qualify as 20' since you've used 2-10' pieces?

 

[crossman]

If you took 2-10' x 1/2" rebars and over lapped them by 1' and tied them the tied together your continuous piece would only be 18' in length. Does this qualify as 20' since you've used 2-10' pieces?

I say that 10 + 10 = 20, even if they were overlapped 5 feet.... that is what the code says.... 20 feet of one or more pieces of rebar.

 

[iwire]

I say that 10 + 10 = 20, even if they were overlapped 5 feet.... that is what the code says.... 20 feet of one or more pieces of rebar.

I agree, with that point and the slab rebar being allowed to be connected but not counting.


Now the real question in my mind, how far outside the pour can we extend with rebar?

In my opinion not even a millimeter per the words in the NEC.

 

[Pierre C Belarge]

I agree, with that point and the slab rebar being allowed to be connected but not counting.


Now the real question in my mind, how far outside the pour can we extend with rebar?

In my opinion not even a millimeter per the words in the NEC.

Some of the local jurisdictions do not permit the rebar to be installed exposed and outside of the pour.

 

[iwire]

Now the real question in my mind, how far outside the pour can we extend with rebar?

In my opinion not even a millimeter per the words in the NEC.

I decided to open a new thread about this.

CEE Rebar Stub Out? I don't think so.

 

[iwire]

Here in NY, we reference the 2002 NEC for dwellings and the 2005 NEC for other occupancies.

A couple of questions.

1. How many jurisdictions out there are enforcing 250.52(A)(3)?

2. If you are enforcing this section, how is it being performed?
a. via the building official during a footing inspection
or
b. the electrical inspector is performing the inspection.

Here is the handout I got in a code update.

Page 1

Page 2

 

[tryinghard]

:roll:

Please pay attention to my point....

The reason i said it is this: I can just see some hOmE InsPecToR or MulTi-CraFt InsPeCtOr telling an EC that it is against code to tie into the rebar because of "that rebar is too short" or "that rebar isn't in the bootom of the footing"?or whatever.

You either have a keyboard problem/twitch/or your passionate about the topic, (I think it?s the latter, and we share this passion)

Around here in the mid 70?s we would tie our GEC onto a rebar stubbed out of footing where the concrete/GC?s framer guy felt it should stub, this was rarely questioned to the electrician for location. Previous to this we usually installed driven rods, water pipe was rarely the electrode choice especially around this time. So the concrete/GC?s framer guy began installing electrical (the electrode), they hated it but began to accept it (I hated it as well and still do).

This evolved to the mid 80?s and our inspection department began enforcing their interpretation of a CEE; they would fail a CEE that was not specifically 20? ?at or near the bottom? this meant most cases because again they were stubbing up a 20?er so maybe only 17?+/- was ?at or near the bottom?. You see this local inspection department did not interpret the CEE to allow wire tie splicing. I thought this was anal but soon embraced it; again I don?t want others doing my work.

My jobs (and eventually my company) began installing our own CEE?s from the late 80?s on, this was good we?re now installing what IS our responsibility ? the electrode. We choose to use the #4 cu as the electrode and not the rebar, so we can care less what the concrete/GC?s framer guy does because our #4 will be compliant to 250.52(A)(3), we do attach it to the footing steel but this is really bonding and electrode system. We also stub out enough to terminate at the ground bus of the service disconnect, so we do not even have a GEC at this place in time unless the stub is too short or service disconnect moves. If this happens we can splice (accessibly) and this splice will be the beginning of our GEC rather than down in the concrete, because our #4 coming out of the concrete IS the electrode.

You see the structural guy sees the rebar as structural that may be an electrode, and if the electrician chooses to use the rebar the electrician sees it as the electrode that may be structural. We have a different emphasis and appropriately so.

I can see how the fact that 250.52(A)(3)?s (incomplete) first sentence is devoid of how the 20? of steel can be achieved so I agree one can understand it to mean wire tying is okay especially after reading the last sentence. With this line of reasoning the #4 may be able to be wire tied but the last sentence probably nullifies this thought? Interesting, the steel ? electrode - can be wire tied but the GEC must connect, you?d think with you?re choice they (not you) would have to use approved connectors? Unless of course your installing the rebar to meet the remaining two elements of a steel CEE.

You see our choice of using the #4 cu electrode still affords us to bond the other electrodes as a system and we do, we just can care less what the footing steel is or is doing!

I think those of you who choose to delegate the electrode installation to a non-skilled craft should also be prepared to use another type of electrode, with steel prices you may see steel less than ??, or fiberglass, or some other non-conductive structure for the concrete used.

How much #4 cu do you use for your GEC when you tie onto a steel CEE?

I average 30? and can care less what the footing steel does!

 

[tryinghard]

:roll:

Please pay attention to my point....

The reason i said it is this: I can just see some hOmE InsPecToR or MulTi-CraFt InsPeCtOr telling an EC that it is against code to tie into the rebar because of "that rebar is too short" or "that rebar isn't in the bootom of the footing" or "that rebar is in a slab, not a foundation" or whatever.

A CEE electrode includes four elements all of which must be met to qualify it as ?an electrode?. Therefore if it is missing any one of the four elements it is NOT an electrode it would simply only be steel. These four elements are listed in two sentences under 250.52(A)(3)

• 
  [1] at least 2? of concrete encasement
  [2] located within and near the bottom of a concrete foundation or footing that is in direct contact with earth
  [3] consisting of at least 20? of: bare/zinc galvanized/other electrically conductive coated steel or 20? of bare copper conductor.
  [4] ?? minimum diameter or #4 bare copper conductor

To tie onto steel that is not an electrode is not a violation its simply bonding, but to tie onto steel that does not meet all four elements of 'a CEE electrode' when its intended application IS TO BE THE ELECTRODE is a violation!

 

[crossman]

I appreciate the interesting commentary concerning your history with CEEs. I am in total agreement with your last post. Again, my entire point, which you understand, is that I can bond to the rebar all day long if I want to, regardless of whether it is a CEE or not. Of course, if it is not a CEE, then I would have to provide the other Code required electrodes, for example:

An electrode system consisting of a single waterpipe must have a supplemental electrode. A CEE could provide this, no ground rod needed. But in the same circumstance, if we bonded to a non-CEE rebar system, we would still need to add the ground rod or other supplemental electrode because the noncompliant rebar is not a CEE even though we bonded to it.

Enough of this line of thought! But it was fun.:smile: