Concrete encased electrode

[J.P.]

I went to a job today to work primarily on a A/c install and to drive a few ground rods on a new build going in.

The ground rods wouldn't drive. They had heavily compacted earth and we ruined one ground rod.

I did some reading in the nec about concrete encased ground rods and ended up tieing 3 8 footers together.

My question is Does it matter where in the footer the cee goes?
As it stands now there is 18" of footer poured and another 18 or so to go. I saw a minimum of 2" of concrete must cover the ground rods/rebar.
I am on top of the initial 18" pour right now.

There was no placement preference in the footing though. At this rate I could have dropped it on top of the rebar for the pad pour.....


Am I horribly mistaken? I am going back tomorrow to work on the A/C install so changing something isn't a problem.

 

[Dennis Alwon]

Article 250 states you need 20' of rebar or you can just install 20' #4 copper and attach it to the rebar that is there. No need to attach to the rebar if it does not qualify but it won't hurt.

As long as the footer is in direct contact with the earth then you are good.

 

[infinity]

Do 3-8' rods tied together in concrete constitute a grounding electrode?

 

[kwired]

ART 250 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.

.....

(3) Concrete-Encased Electrode. A concrete-encased
electrode shall consist of at least 6.0 m (20 ft) of either
(1) or (2):
(1) One or more bare or zinc galvanized or other electrically
conductive coated steel reinforcing bars or rods of
not less than 13 mm (1?2 in.) in diameter, installed in
one continuous 6.0 m (20 ft) length, or if in multiple
pieces connected together by the usual steel tie wires,
exothermic welding, welding, or other effective means
to create a 6.0 m (20 ft) or greater length; or
(2) Bare copper conductor not smaller than 4 AWG
Metallic 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.


Informational Note: Concrete installed with insulation, vapor
barriers, films or similar items separating the concrete
from the earth is not considered to be in ?direct contact?
with the earth.

Read this carefully, it is telling you that if a CEE exists in the footing you must use it as a grounding electrode, that is if the design has steel reinforcement in it that meets the requirements you must use that steel. If there is no steel reinforcement then you have the option of making your own CEE by adding at least 20 feet of rebar or 20 feet of 4AWG copper.

This CEE must be in a concrete foundation that is in direct contact with earth. A second layer of concrete on top of the original footing may or may not meet qualifications for it to be a CEE - which is what I think you are saying you are attempting to install this in.

 

[J.P.]

Do 3-8' rods tied together in concrete constitute a grounding electrode?

I think so. It says electrically conductive rods or just bare wire #4 or larger.

As long as the length is 20ft when you get it tied together.

 

[J.P.]

ART 250 PART III - Grounding Electrode System and Grounding Electrode Conductor




Read this carefully, it is telling you that if a CEE exists in the footing you must use it as a grounding electrode, that is if the design has steel reinforcement in it that meets the requirements you must use that steel. If there is no steel reinforcement then you have the option of making your own CEE by adding at least 20 feet of rebar or 20 feet of 4AWG copper.

This CEE must be in a concrete foundation that is in direct contact with earth. A second layer of concrete on top of the original footing may or may not meet qualifications for it to be a CEE - which is what I think you are saying you are attempting to install this in.

I don't see the part where it says you " MUST " use the rebar. I see where the rebar is an option.

I can still use the rebar for the pad if I need to. They are compacting gravel right now and haven't put the grid down yet.

 

[infinity]

I think so. It says electrically conductive rods or just bare wire #4 or larger.

As long as the length is 20ft when you get it tied together.

You're right, I just blew right past the part that said rods.

I don't see the part where it says you " MUST " use the rebar. I see where the rebar is an option.

I can still use the rebar for the pad if I need to. They are compacting gravel right now and haven't put the grid down yet.

I agree it's an either/or situation where you can choose. If you prefer #4 copper as opposed to steel rebar you can use the copper.

 

[jim dungar]

I can still use the rebar for the pad if I need to.

A pad does not count for use as a CEE, you must use a footing.

 

[iwire]

I don't see the part where it says you " MUST " use the rebar. I see where the rebar is an option.

If a concrete electrode exists you have to use it.

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.....

 

[Dennis Alwon]

A pad does not count for use as a CEE, you must use a footing.

Just to clarify- the 2011 allows the use of the foundation also. I agree that the slab is a no no,

 

[GoldDigger]

But if the slab pour uses rebar which is tied to the rebar in the already poured footings or, IMHO, is poured over the footings and contains its own sufficient length of rebar, it could comply.

Tapatalk!

 

[kwired]

I don't see the part where it says you " MUST " use the rebar. I see where the rebar is an option.

I can still use the rebar for the pad if I need to. They are compacting gravel right now and haven't put the grid down yet.

If a concrete electrode exists you have to use it.

Exactly what I was trying to point out. The footing guys likely are using "rebar" and not ground rods in their footing. If it exists then 250.50 says it must be used. If it doesn't exist then you have the option to create your own CEE and that could be with other acceptable material as mentioned