Concrete encased electrode for residential home?

[tom baker]

For the OPer, the reason why ground rods are not required with a Ufer is:
250.53 D 2 requires a supplemental electrode for a metal UG water pipe, of a type specified in 250.52A 2 thru A 8, IE metal structure, CEE, ground ring, rod, other listed, plate or other UG structures
The reason for this requirement is that metal UG water pipes (starting in the 1950s) were being replaced with plastic pipes
If you have a Ufer of CEE ground, then it does not need to be supplemented.
But if you install a rod, then it becomes part of the "grounding electrode system"
In ten years, our institutional knowledge and handed down electrical information will be gone. On the job it will be the
Old guy saying, back in the day we had to drive ground rods
New guy, whats a ground rod?

 

[Flanative]

The NEC only requires use of a UFER in new construction if the footer construction provides for one.
You can get into a real bind if the rebar qualifies to be a UFER but no connection was made to it before pouring. You then have to chip out concrete to make an attachment point.
Some jurisdicrtions, however, require a UFER in all new construction, even if you have to lay copper wire in the footer to create one. If you skip this step in those areas you are really in trouble.

I’m not following what your saying. Because in our area the ufer area is inspected prior to pouring the slab to make sure there is no vapor barrier and the rebar is continuous. No connection is made until rough in and that is made in the wall behind a 2- gang blank in the hollow portion of the cell.

 

[jaggedben]

I hadn't quite realized that the NEC doesn't require a CEE (or building steel) in new construction). Is there another section of commonly adopted building codes that requires it? It's certainly treated that way in my area. Like if you pour more than 10ft of footing you need to install a CEE. It certainly makes sense in my not-quite-expert opinion, as I think a CEE may actually do something a meaningful percentage of the time it's needed, whereas a pair of ground rods, practically speaking, probably does nothing meaningful most of the time.

 

[LarryFine]

To me, a CEE is a gift to us, especially if you can arrange the access at the service.

 

[tom baker]

No misunderstanding at all. Here is how Mr Holt explains it - see 250.4(A)(1). Can a ufer ground take a full load of lighting current? Cell towers have extensive ufer grounds, the one I installed had a concrete mat 10x10x4 for a 100 ft tower

 

[Dennis Alwon]

I hadn't quite realized that the NEC doesn't require a CEE (or building steel) in new construction). Is there another section of commonly adopted building codes that requires it? It's certainly treated that way in my area. Like if you pour more than 10ft of footing you need to install a CEE. It certainly makes sense in my not-quite-expert opinion, as I think a CEE may actually do something a meaningful percentage of the time it's needed, whereas a pair of ground rods, practically speaking, probably does nothing meaningful most of the time.

The nec does require a concrete encase electrode and building steel if they are available. For new construction these are always available.

 

[kwired]

The nec does require a concrete encase electrode and building steel if they are available. For new construction these are always available.

But only if they are present - which is the key word in 250.50. Might not be that common in most general applications that they not be present though.

Thermal or vapor barrier I wouldn't think would be as common on a footing as it maybe is on slabs and walls.

Most building codes likely require reinforcement that also does make it qualify as a CEE so that is likely number one reason they normally will be present.

 

[kwired]

I wired a new pole type building somewhat recently. concrete slab floor inside - no "footing" anywhere. Nothing for a naturally existing CEE to reside in so no CEE required by NEC.

 

[Dennis Alwon]

But only if they are present - which is the key word in 250.50. Might not be that common in most general applications that they not be present though.

Thermal or vapor barrier I wouldn't think would be as common on a footing as it maybe is on slabs and walls.

Most building codes likely require reinforcement that also does make it qualify as a CEE so that is likely number one reason they normally will be present.

So when is building steel not present. Just the mention of it I assumed meant these items were there. And I did say if they are available (present)

 

[jaggedben]

The nec does require a concrete encase electrode and building steel if they are available. For new construction these are always available.

That doesn't speak to my comment or question. (Also building steel isn't available in wood frame construction, but I gather you meant at least one of them will be available.) Is there a code that requires a CEE in new construction? Or is it just a common local code or enforcement practice? Because the NEC is not that code.

 

[Dennis Alwon]

Here you decide

Part III. Grounding Electrode System and Grounding Electrode
Conductor
250.50 Grounding Electrode System. All grounding electrodes
as described in 250.52(A)(1) through (A)(7) that are
present at each building or structure served shall be bonded
together to form the grounding electrode system. Where none
of these grounding electrodes exist, one or more of the
grounding electrodes specified in 250.52(A)(4) through
(A)(8) shall be installed and used.
Exception: 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.

 

[jaggedben]

Here you decide

Yes that in no way requires a CEE, whether in new construction or not. For example if a vapor barrier is installed all around the foundation, then the rebar doesn't qualify as a CEE. Therefore a CEE would not exist, therefore the NEC wouldn't require it to be used.

 

[infinity]

Yes that in no way requires a CEE, whether in new construction or not. For example if a vapor barrier is installed all around the foundation, then the rebar doesn't qualify as a CEE. Therefore a CEE would not exist, therefore the NEC wouldn't require it to be used.

That a correct a CEE is never required unless the rebar in the footing qualifies as an electrode. Then you have a choice, create your CEE by installing 20' or more of bare #4 copper in the footing or connect to the 20' or more of 1/2" rebar in the footing that is in direct contact with the earth. Start with does the rebar qualify and then choose how you will use the CEE.

 

[Dennis Alwon]

Yes that in no way requires a CEE, whether in new construction or not. For example if a vapor barrier is installed all around the foundation, then the rebar doesn't qualify as a CEE. Therefore a CEE would not exist, therefore the NEC wouldn't require it to be used.

Of course, it isn't required if it doesn't exist. If there is plastic down then it is not an electrode. The premise I made was based on those electrodes being available then the NEC requires you to use it.

 

[jaggedben]

Once again, my question is, does anyone know of another code that is the basis for AHJs requiring proper installation of a CEE in new construction? Or should I assume it's just local rules and enforcement practices?

 

[wwhitney]

Or should I assume it's just local rules and enforcement practices?

My jurisdictional experience is surely more limited than yours, but I don't believe there are actually any local requirements beyond the NEC. Local practice for foundation design almost always results in the creation of a CEE, so it must be used per the NEC. But to my knowledge if you have a project with a foundation design that doesn't result in a CEE, plans examiners aren't going to require you to modify the foundation design to create a CEE.

I checked Berkeley's amendments, they do require that any footing have at least #4 rebar, but I see no prohibition on a vapor barrier under the footing.

Cheers, Wayne

 

[kwired]

Once again, my question is, does anyone know of another code that is the basis for AHJs requiring proper installation of a CEE in new construction? Or should I assume it's just local rules and enforcement practices?

It is local rules or enforcement practices.

NEC language alone does not make you provide a CEE if there isn't otherwise one there. You are still free to create one if you so choose. Like encasing 20(+) feet of 4 AWG where qualifying rebar is not present.

 

[kwired]

My jurisdictional experience is surely more limited than yours, but I don't believe there are actually any local requirements beyond the NEC. Local practice for foundation design almost always results in the creation of a CEE, so it must be used per the NEC. But to my knowledge if you have a project with a foundation design that doesn't result in a CEE, plans examiners aren't going to require you to modify the foundation design to create a CEE.

I checked Berkeley's amendments, they do require that any footing have at least #4 rebar, but I see no prohibition on a vapor barrier under the footing.

Cheers, Wayne

Yes, most cases building codes likely result in a qualifying electrode likely being present. Could be ways around the building code that won't require the rebar, but they also likely either less practical or more expensive and the use of rebar happens the majority of the time.

 

[wwhitney]

Yes, most cases building codes likely result in a qualifying electrode likely being present.

The common solutions result in a qualifying electrode, but there are compliant designs that don't E.g. a vapor barrier under footing (maybe a shallow frost protected foundation), or non-conductive rebar (fiberglass or basalt).

Cheers, Wayne

 

[infinity]

Yes, most cases building codes likely result in a qualifying electrode likely being present. Could be ways around the building code that won't require the rebar, but they also likely either less practical or more expensive and the use of rebar happens the majority of the time.

Years ago we did several additions where the Architect specified 3/8" rebar so no CEE was required. Whether or not there is a CEE required is a building code issue not a NEC issue.