Concrete Encased Electrodes

[edhelderman]

I work for a manufacturer of precast foundation walls for residential homes and we make no provision to ground our walls electrically as there is no exposed re bar on our walls. Some code officials want them to be grounded but this would cause us to make a provision for this in the design and we have not currently taken those steps. I don't see anywhere where the code requires a foundation to be grounded as long as other grounding provisions are adequate.

Is it the intent of the code to require that a precast foundation be grounded?

 

[1793]

Re: Concrete Encased Electrodes

I'm sure someone will have something to say about this:

We are not grounding your walls, your walls are grounding us.

Norb

 

[petersonra]

Re: Concrete Encased Electrodes

I think the answer is that if it is present you have to bond to the steel in the concrete foundation (at least in the 2005 code)

If there is no steel in the foundation, than no bdoning is required.

 

[edhelderman]

Re: Concrete Encased Electrodes

Reply to Bob...who said...I think the answer is that if it is present you have to bond to the steel in the concrete foundation (at least in the 2005 code)

If there is no steel in the foundation, than no bdoning is required.

_____________________________________
Bob,

I just found an exception in the NEC that states that "Concrete-encased electrodes of existing buildings or structures shall NOT be required to be part of the grounding electrode system where the steel reinforcing bars or rods are not accessible for use without disturbing the concrete."

I did not see this the first time I read it. This gives our precast walls a definite exemption to the grounding system.

Ed

 

[jim dungar]

Re: Concrete Encased Electrodes

There is a difference between precast walls and concrete footings. 250.52(A)(3) says a concrete encased electrode is the foundation or footing in direct contact with the earth not separate concrete walls which are probably coated with a moisture barrier.


IMO, no exposed rebar - no bonding required.

edited typos (what else is new)

[ August 31, 2005, 06:31 PM: Message edited by: jim dungar ]

 

[raider1]

Re: Concrete Encased Electrodes

If the precast panels are set on footings that are poured in place at the site, than use the rebar in the footing and don't worry about the panels.

Chris.

 

[allenwayne]

Re: Concrete Encased Electrodes

There is a precast home being built nearby i`LL STOP

 

[allenwayne]

Re: Concrete Encased Electrodes

There is a precast home being built neaby,I`ll stop by and see what they required..but I bet the ufer is in the slab.Separate from walls

 

[electricmanscott]

Re: Concrete Encased Electrodes

The precast walls I have seen do not sit on a footing other than crushed stone.
Do your walls actually contain any rebar? If it does it must be used in my opinion.
That exception would not apply to your situation.
That exception applies to existing buildings or structures. Yours is not existing it is a new installation.

 

[sandsnow]

Re: Concrete Encased Electrodes

I think the keyword in the question is "foundation" walls.

Are the walls acting as a foundation for the building?

If so, then one of your walls would have to be provided with a means to make it happen.

 

[paul]

Re: Concrete Encased Electrodes

No bonding to your rebar needed. It's the bar in the footings that we want. The bar in cast walls are seperate from the footings and are absolutely useless for a ufer ground.

 

[electricmanscott]

Re: Concrete Encased Electrodes

We need info to give a correct answer.
Do these foundation walls sit on a footing?
Is there rebar in them?

 

[don_resqcapt19]

Re: Concrete Encased Electrodes

edhelderman,
If the precast walls are the building foundations, and if they have at least 20' of #4 or larger rebar, and if the walls are in direct contact with the earth, then the 2005 code requires that the rebar be used as a grounding electrode. There are no exceptions if all of the conditions lists above are met.
Don

 

[edhelderman]

Re: Concrete Encased Electrodes

I want to thank everyone for their input on this matter.

I will take your comments under advisement.

Sincerely,

Ed Helderman

 

[JohnE]

Re: Concrete Encased Electrodes

Ed,

I basically agree with Don where if rebar is in precast wall, then you must use it as a grounding electrode.

However, if there is a footing which has a concrete encased electrode, then you do not need to use the rebar in the wall.

There was an extensive discussion several weeks ago on this forum relating to this matter.

John

 

[steve66]

Re: Concrete Encased Electrodes

Posted by electricmanscott:

That exception applies to existing buildings or structures. Yours is not existing it is a new installation.

I'm still wondering about this. A precast wall can be called a "structure". So if they are built at the factory and delivered to the site, in a way they are existing. But I'm not sure if thats what the NEC means by existing.

Steve

 

[electricmanscott]

Re: Concrete Encased Electrodes

Originally posted by steve66:
Posted by electricmanscott:

That exception applies to existing buildings or structures. Yours is not existing it is a new installation.

I'm still wondering about this. A precast wall can be called a "structure". So if they are built at the factory and delivered to the site, in a way they are existing. But I'm not sure if thats what the NEC means by existing.

Steve

Steve I'd say this is a HUGE stretch.

 

[jwelectric]

Re: Concrete Encased Electrodes

Well I guess I don?t need to bond that service panel. It was built at Westinghouse and shipped here so in must be existing and can be grandpa in.