UFER grounding

[Joe.B]

Can you simplify if it is a good ground or not?

Most of the users here are working in an area where the NEC is a code requirement. We don't typically get a choice on things. The code says "Do this, don't do that." The code is not a design manual, it is a minimum standard to make electrical systems in the US as safe as they can be.

To answer the questions you're asking, you probably need an experienced electrical engineer who can get a good analysis of the complete situation, maybe even see it in person. What type of soil is it? What's the ph? How wet is it? There are a bunch of unknow factors.

Also, consider that your application is fairly unique. You have an off-grid system you're trying to design, correct? If the design specifications call for a grounding electrode system, than the designer (you I presume) need to determine what electrodes are available, and if none are, then create one.

It sounds like you've established that you have a CEE. A Concrete Encased Electrode is generally known to be a "good ground", certainly better then a ground rod hammered into the ground.

 

[petersonra]

The rebar is in building's columns. Total depth of column under ground ecased with concrete is over 15' confirmed.then the columns are raised to first floor (12' hieght) where rebar is protruding from column.
If this infromation suffices.

If the rebar is in columns it would not constitute a CEE. It has to be in the footing or foundation and oriented horizontally.

 

[don_resqcapt19]

If the rebar is in columns it would not constitute a CEE. It has to be in the footing or foundation and oriented horizontally.

He said

Total depth of column under ground ecased with concrete is over 15'

I see that as the concrete encased electrode and the rebar, assuming it is all connected by the standard tie wires, subbed out at 12" AFF is just a connection point for the GEC as permitted by 250.68(C)(3)
350.53(A)(3) says.

Metal components shall be encased by at least 50 mm (2 in.) of concrete and shall be located horizontally within that portion of a concrete foundation or footing that is in direct contact with the earth or within vertical foundations or structural components or members that are in direct contact with the earth. If multiple concrete-encased electrodes are present at a building or structure, it shall be permissible to bond only one into the grounding electrode system.

 

[petersonra]

He also said the rebar is in a column in one of his posts. Columns are generally considered to be vertical.

 

[don_resqcapt19]

He also said the rebar is in a column in one of his posts. Columns are generally considered to be vertical.

Yes they are vertical and vertical foundations or structural components are specifically permitted to be used as concrete encased electrodes. A vertical column in the earth is a "structural component".

 

[Joe.B]

Th OP's questions don't fall under the scope of NEC, he's really just asking if (in our opinion) his CEE would be a good electrode. Assuming his 15 foot column has a bunch of rebar in it, I'm pretty sure it would be a better electrode that a 10 foot ground rod.

 

[LarryFine]

Assuming his 15 foot column has a bunch of rebar in it, I'm pretty sure it would be a better electrode that a 10 foot ground rod.

 

[jim dungar]

We need some clarification, but I read it as being a vertical column at least 15' down in the dirt and then 12' up in the air, with exposed rebar at the top. This is a common construction technique in many countries.

 

[petersonra]

Yes they are vertical and vertical foundations or structural components are specifically permitted to be used as concrete encased electrodes. A vertical column in the earth is a "structural component".

How do you get around the requirement the rebar be horizontal?

 

[SAL568]

We need some clarification, but I read it as being a vertical column at least 15' down in the dirt and then 12' up in the air, with exposed rebar at the top. This is a common construction technique in many countries.

You read it correct

 

[SAL568]

Th OP's questions don't fall under the scope of NEC, he's really just asking if (in our opinion) his CEE would be a good electrode. Assuming his 15 foot column has a bunch of rebar in it, I'm pretty sure it would be a better electrode that a 10 foot ground rod.
View attachment 2572966 View attachment 2572967

Here is the site preview. Qs is can I use one of/ any of the protruding rebar as a grounding for Solar system?

 

[SAL568]

As for the electrical code here in Pakistan what I have come across is as follows:

 

[SAL568]

These codes in general are not applied.

 

[GoldDigger]

How do you get around the requirement the rebar be horizontal?

"shall be located [horizontally within that portion of a concrete foundation or footing that is in direct contact with the earth] or within vertical foundations or structural components or members that are in direct contact with the earth"
It all comes down to the scope of the "or". You think that "horizontally is outside the first part of the "or". I think it is contained within it. Talking about rebar located horizontally within vertical foundations is too illogical even for the NEC, IMNSHO.
I do agree that the relevant 20' of rebar should all be located below ground level. So we cannot count the 15' of the column which is above ground. But the 20' can consist of two or more parallel shorter sections within the below-ground portion of the column.

 

[don_resqcapt19]

How do you get around the requirement the rebar be horizontal?

I simply do not read it that way, but I can see that is what it says.

That is just very poor wording, however given the horizontal rings the tie the vertical bars together, I would expect it does have 20' of bar in the horizontal orientation. When this section was rewritten for the 2011 code, the language was changed without any technical substantiation, looking at the proposal, it was not the intent to remove the language that appeared in the 2008 code.

... An electrode encased by at least 50 mm (2in.) of concrete, located horizontally within and near the bottom or vertically,
and within that portion of a concrete foundation or footing that is in direct contact with the earth...

But the actual language does say what you say....just not going to enforce it that way around here.

 

[jim dungar]

I simply do not read it that way, but I can see that is what it says.

That is just very poor wording, however given the horizontal rings the tie the vertical bars together, I would expect it does have 20' of bar in the horizontal orientation. When this section was rewritten for the 2011 code, the language was changed without any technical substantiation, looking at the proposal, it was not the intent to remove the language that appeared in the 2008 code.


But the actual language does say what you say....just not going to enforce it that way around here.

Aren't footing typically horizontal more than the are vertical, so these would be covered by the test before the first or? Aren't foundation walls and structural columns typically more vertical than footings, so these would be covered by the text after the first or?

 

[tortuga]

I am just curious is this project in Pakistan what is it?
A building being designed for North American equipment like foreign worker housing, a hotel or a hospital or something?

 

[don_resqcapt19]

Aren't footing typically horizontal more than the are vertical, so these would be covered by the test before the first or? Aren't foundation walls and structural columns typically more vertical than footings, so these would be covered by the text after the first or?

The intent of the code change was to permit both the use of horizontal footings, and vertical structural elements. What that language was added vertical columns were specifically cited.

 

[SAL568]

I am just curious is this project in Pakistan what is it?
A building being designed for North American equipment like foreign worker housing, a hotel or a hospital or something?

Yes this project is in Pakistan. The off grid solar system needs to be installed in, however there is no grounding/earthing electrode except CEE rebars on first floor. The coloumn size is 10"×20" and 15' down in earth where it's held by footing of 3'×3'×5". My qs is if I can use these rebars as grounding electrode for earthing the Solar system & equipements.

 

[SAL568]

I thank you all for such an amazing helpful discusion