Re-Bar for a Ground Rod

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1

Originally Posted By: anatol polillo
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Fellow Inspectors,


In the townhouse today (Slab) The ground conductor was at the box and tied to a peice of re-bar driven into the ground and covered (surrounded) by the floor (pour). I Assumed (don’t start) that this was ok, but this is the first time I have not seen a copper ground rod. All of the water pipes were cpvc, so pipes are not an option. Did I miss a big one here, or is this ok?


Anatol

2

Originally Posted By: jpeck
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If that rebar serves as the ground rod, it is an incorrect choice of material for a ground rod, however, if that rebar serves as the connection to the slab or footing steel, it is an incorrect choice of location and method of connection to the foundation steel.


In other words, it is incorrect either way, but for different reasons.

Recommend the electrician properly ground the electrical system.

--
Jerry Peck
South Florida

3

Originally Posted By: Bob Badger
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jpeck wrote:
however, if that rebar serves as the connection to the slab or footing steel, it is an incorrect choice of location and method of connection to the foundation steel.


Jerry I almost hate to ask but how do you know if the connection is incorrect or that the location is wrong?

All I am saying is Anatol did not explain the type of connection and as far as location the rebar can be bent like a "L" so that part of it sticks up through the slab.

Strange as it sounds I have read that some areas require doing that so the connection is accessible.

If the rebar is serving as a ground rod and it is larger than 5/8" diameter I believe it is allowed, I have never done so but 250.52(A)(5)(b) seems to allow it.

--
Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum
4

Originally Posted By: jpeck
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Bob Badger wrote:
jpeck wrote:
however, if that rebar serves as the connection to the slab or footing steel, it is an incorrect choice of location and method of connection to the foundation steel.


Jerry I almost hate to ask but how do you know if the connection is incorrect or that the location is wrong?


Bob,

Because all reinforcing steel must be protected with concrete cover, and that is exposed. The grounding bond to the footer steel needs to go to the footer steel and be buried in the concrete pour, with the appropriate clamp, of course. The exposed rebar is not protected with any type of coating and will rust.

Quote:
All I am saying is Anatol did not explain the type of connection and as far as location the rebar can be bent like a "L" so that part of it sticks up through the slab.

Strange as it sounds I have read that some areas require doing that so the connection is accessible.


Yes, that would be strange because that would the footer reinforcing steel exposed, see above and below 250.68 (A) reference on accessibility.

250.68 Grounding Electrode Conductor and Bonding Jumper Connection to Grounding Electrodes.
(A) Accessibility. The connection of a grounding electrode conductor or bonding jumper to a grounding electrode shall be accessible.
Exception: An encased or buried connection to a concrete-encased, driven, or buried grounding electrode shall not be required to be accessible.

Also, it does not meet this in its entirety because it is not concrete encased in its entirety, the bent upward portion is acting as the grounding electrode conductor.

250.52(A)
(3) Concrete-Encased Electrode. An electrode encased by at least 50 mm (2 in.) of concrete, located within and near the bottom 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 (? 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.

Quote:
If the rebar is serving as a ground rod and it is larger than 5/8" diameter I believe it is allowed, I have never done so but 250.52(A)(5)(b) seems to allow it.


While it may be allowed, how would one know it meets the 8' minimum length in contact with soil requirement in 250.53 (A) and (G).

250.52(A)(5) Rod and Pipe Electrodes. Rod and pipe electrodes shall not be less than 2.5 m (8 ft) in length and shall consist of the following materials.
(a) Electrodes of pipe or conduit shall not be smaller than metric designator 21 (trade size ?) and, where of iron or steel, shall have the outer surface galvanized or otherwise metal-coated for corrosion protection.
(b) Electrodes of rods of iron or steel shall be at least 15.87 mm ( in.) in diameter. Stainless steel rods less than 16 mm ( in.) in diameter, nonferrous rods, or their equivalent shall be listed and shall not be less than 13 mm (? in.) in diameter.

--
Jerry Peck
South Florida
5

Originally Posted By: anatol polillo
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There is no way to tell if the re-bar is bent and bonded to anything else. As I saw it, it appeared to be driven in. I will append the report and ask the electrician to make the judgement. The location of the box would make it easy to drive a ground rod outside and make a correct connection to the box.


Thanks, Anatol

6

Originally Posted By: Bob Badger
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Jerry how do we know the length of any ground rod? icon_confused.gif


Or the length of a piece of 3/4" conduit that is allowed to be used as as Grounding electrode?

Quote:
Because all reinforcing steel must be protected with concrete cover, and that is exposed.


Do you have a code reference for that?

I see no requirement that all rebar must be encased, I see that a minimum of 20' must be encased and that you can join smaller pieces together with the usual steel tie wires.

Quote:
Also, it does not meet this in its entirety because it is not concrete encased in its entirety, the bent upward portion is acting as the grounding electrode conductor.


So if I use a 10' ground rod I can not leave a foot above the ground because then it is being used as a GEC? (Forget about the physical damage aspect for now)

If you have 20' of rebar located in the proper location and add a "L" shaped piece onto it and you meet the code.

I am aware of 250.68 (A) as the rebar connections I do are encased in the pour made with a cad weld.

Bob

--
Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum
7

Originally Posted By: Bob Badger
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Jerry my point here is you can not make a “blanket” statement (as you pointed out to Mike P) that this is always incorrect.


It may be incorrect but with the info you and I have we can not say it is incorrect.

--
Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum

8

Originally Posted By: jpeck
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Bob Badger wrote:
Jerry my point here is you can not make a "blanket" statement (as you pointed out to Mike P) that this is always incorrect.

It may be incorrect but with the info you and I have we can not say it is incorrect.


Got caught on my own admonishment, dang. You set me up for that, didn't you? ![icon_biggrin.gif](upload://iKNGSw3qcRIEmXySa8gItY6Gczg.gif) I know, we all do it, but none of us should do it (make blanket statements). I'll just wallow over to my corner again.

--
Jerry Peck
South Florida
9

Originally Posted By: jfarsetta
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Sometimes, mats or grounding pads are used, but they are typically bonded to building steel via the use of cad-welded connections.


Ive seen this in commercial installations, and never in a home. Maybe in an apartment building, but kinda rare. NYC has all sorts of grounding problems in the city-proper. SOmetimes, a ground rod cant be driven.

Ive seen re-bar used for a ground rod. Not the best choice of material, I suppose.

--
Joe Farsetta

Illigitimi Non Carborundum
"Dont let the bastards grind you down..."

10

Originally Posted By: Bob Badger
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Joe I do not know much about home building here in MA but I have read on the forums that NJ for one requires the use of concrete encased electrodes on all new construction. This is beyond NEC requirements.


They are much better than rods and are almost impervious to damage.

--
Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum

11

Originally Posted By: jpeck
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Bob,


Am I understanding you incorrectly?

" ... that NJ for one requires the use of concrete encased electrodes on all new construction. This is beyond NEC requirements."

That is an NEC requirement.

250.50 Grounding Electrode System.
If available on the premises at each building or structure served, each item in 250.52(A)(1) through (A)(6) shall be bonded together to form the grounding electrode system. Where none of these electrodes are available, one or more of the electrodes specified in 250.52(A)(4) through (A)(7) shall be installed and used.
250.52 Grounding Electrodes.
- (A) Electrodes Permitted for Grounding.
- - (1) Metal Underground Water Pipe.
- - (2) Metal Frame of the Building or Structure.
- - (3) Concrete-Encased Electrode.
- - (4) Ground Ring.
- - (5) Rod and Pipe Electrodes.
- - (6) Plate Electrodes.

Or are you referring to something as a "Concrete-Encased Electrode" which is outside that described in 250.52(A)(3)?

I am envisioning that you may be referring to something like making a 5" hole in the ground, pouring it full of concrete, then driving a ground rod down the center (leaving it encased in 2" of concrete all around the electrode. That would be weird, and beyond the NEC. Are you referring to something like that?

--
Jerry Peck
South Florida

12

Originally Posted By: Bob Badger
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Good morning Robert,


Notice it says "if available" many times in this area footings are done before electric contractors are signed on, making the footings "unavailable" to install the GEC to.

Here so far no one seems to have a problem with that, other areas this would not be acceptable.

Bob

--
Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum

13

Originally Posted By: jpeck
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Down here, “if available” means that if it’s installed, somebody (builder, electrician, somebody) better make darn sure they are not poured without someone installing the grounding electrode conductor to it, using a proper clamp, and it had better be inspected BEFORE the pour, or someone is going to be doing a lot of chipping out and patching.


It "is available" if it is there. The code says "if available", not "if accessible".

--
Jerry Peck
South Florida

14

Originally Posted By: Bob Badger
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Jerry that is fine but I do not think RI, NY or MA holds that view.


From hanging out at other national forums it seems the states that do hold the FL view are in the minority.

Not at all saying our way is better than your way, just that the National Electric Code is not enforced the same in each state.

Personally I think the concrete electrode is the way to go.

But if there is no EC contracted to the job before the footings get poured it is not used.

If we do use it inspections are a must.

As far as chipping into a footing the building inspector may have a problem with that.

Bob

--
Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum