Grounding electrode conductor

[gfretwell]

I did hear one solution to the turned up rebar problem that seemed to work. Once you get the wall built and the panel is set, connect with a copper #4, pour that cell solid with concrete up past the concrete listed acorn. Then the rebar is encased in 2" of concrete.

 

[Dennis]

I don't have an issue with this at all as I install it in the footer. I realize it means another trip but I have trained my builders on what to do so I give them the material if the job is a long way from home. Inspectors are fine with this as long as it is installed correctly.

 

[gfretwell]

The Ufer has been standard here for so long that the concrete guys know to do it and the structural inspector signs it off before the pour. I was putting an addition on my house and the concrete guys put in a Ufer, even though this was part of the existing building. They just did it put of habit. I ended up tying it back to my grounding system anyway. You can't have too much ground.

 

[chris kennedy]

The Ufer has been standard here for so long that the concrete guys know to do it and the structural inspector signs it off before the pour.

In South Florida East Coast we still install and get signed off by the EI.

 

[ICE]

In my part of the jungle, the EI and the SI R I...along with the PI,MI and GI...aye yi yi

 

[jwelectric]

North Carolina amended it to say if available instead of if present.

On residential and small commercial jobs it is not unusual for the footer and foundation to be in before the electrical contract is ever let out and the DOI says that there would be too many issues of cutting the footer in order to establish the CEE should the foundation be in place. In most big commercial and industrial installations of a new building the CEE is installed.

As to the upturned rebar, in the 2011 edition of the NEC we are told in 250.64 that the grounding electrode conductor shall be copper, aluminum or copper clad aluminum. 250.68© gives us two exceptions to this with a metal water pipe and the steel of a building. As defined a grounding electrode is a direct connection to earth. Any part of a rebar that is upturned and not in contact with earth would not be electrode nor would it fit into the grounding path of 250.64.

Sometimes in the electrical trade we have something we call the standard of practice that is nowhere close to being code compliant. This upturned rebar is just one of several that I am aware of.

 

[steveray]

Shouldn't the upturned rebar be OK as it is tied to the footing rebar with the usual steel tie wires? And didn't the language change a bit from my 05 NEC where it says nearest the bottom to something like anywhere you can hit it?

North Carolina amended it to say if available instead of if present.On residential and small commercial jobs it is not unusual for the footer and foundation to be in before the electrical contract is ever let out and the DOI says that there would be too many issues of cutting the footer in order to establish the CEE should the foundation be in place. In most big commercial and industrial installations of a new building the CEE is installed.

As to the upturned rebar, in the 2011 edition of the NEC we are told in 250.64 that the grounding electrode conductor shall be copper, aluminum or copper clad aluminum. 250.68© gives us two exceptions to this with a metal water pipe and the steel of a building. As defined a grounding electrode is a direct connection to earth. Any part of a rebar that is upturned and not in contact with earth would not be electrode nor would it fit into the grounding path of 250.64.

Sometimes in the electrical trade we have something we call the standard of practice that is nowhere close to being code compliant. This upturned rebar is just one of several that I am aware of.

 

[ICE]

Shouldn't the upturned rebar be OK as it is tied to the footing rebar with the usual steel tie wires? And didn't the language change a bit from my 05 NEC where it says nearest the bottom to something like anywhere you can hit it?

2008 NEC

250.52(A)(3) Concrete-Encased Electrode. An electrode encased

by at least 50 mm (2 in.) of concrete, located horizontally

near the bottom or vertically, and within that portion of a

concrete foundation or footing that is in direct contact with

the earth, consisting of at least 6.0 m (20 ft) of one or more

bare or zinc galvanized or other electrically conductive

coated steel reinforcing bars or rods of not less than 13 mm

(½ in.) in diameter, or consisting of at least 6.0 m (20 ft) of

bare copper conductor not smaller than 4 AWG.

Reinforcing bars shall be permitted to be bonded together

by the usual steel tie wires or other effective means. Where

multiple concrete-encased electrodes are present at a

building or structure, it shall be permissible to bond only

one into the grounding electrode system.

 

[codeworks]

page 239 of the 2011 nec handbook covers in real nice detail. commentray, code and pictures , too!

 

[jwelectric]

page 239 of the 2011 nec handbook covers in real nice detail. commentray, code and pictures , too!

To qualify as a grounding electrode, the horizontal or vertical installation of the steel reinforcing rod or the 4 AWG bare copper conductor within the concrete encasement is to be in one continuous 20 ft length so that there is a 20 ft long electrode in contact with the earth. Shorter lengths of reinforcing rod can be connected together to form an electrode 20 ft or longer using the connection methods identified in this requirement. Section 250.52(A)(3) only requires that a single concrete-encased electrode be incorporated into the grounding electrode system. Some buildings or structures may have discontinuous segments of a footing or foundation that individually qualify as grounding electrodes per this section, and once one has been bonded to the grounding electrode system, the remaining ones are exempt from any bonding or grounding requirements. Exhibit 250.23 shows an example of a concrete-encased electrode embedded horizontally. As indicated in the informational note, direct contact with the earth means that there is no medium between the concrete and the earth that impedes the grounding connection or insulates the concrete from being in direct contact with the earth.

 

[gfretwell]

One remediation I have heard of if an inspector did say the upturned rebar was not poured in the concrete was to pour that cell of the block solid, up past the copper connection after the house was dried in.

The reason they started this in the first place was a piece of 4 ga sticking out of the foundation would not usually survive the building process.

 

[SCBO1]

Q1) If the CEE is in the footing and insulation is installed on one or both sides of the footing but not on the bottom side would that be allowed by code?

Q2) The code does not say that a CEE thats 1/2 inch x 20ft long can't be bent, like in the corner or a step footing, would that be allowed?

pc1

 

[gfretwell]

The question comes up here with the Visqueen under the slab on a mono slab footer. They have to stop the Visqueen before they get to the bottom of the footer "bell".

 

[codeworks]

pc, yes to both your questions. #1, as long as the bottom of the footting, is in contact with the earth, and the steel ( or cee attached thereto) is in the bottom, it's good. to # 2, yes , it can be bent, nowhere does it say it has to be straight, so long as its a minimum of 20 feet . irf you have access to a nec handbook check thast out. i have 2005 nec handbook, and a 2011 here, and they both provide good descriptive text and pics

 

[Dennis]

The slab doesn't really come into play for a CEE. I have seen some contractors who want to use the slab but that would not be code compliant. The footer as stated in the post above by codeworks is fine.