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#168736 - 09/13/07 03:06 PM Re-Bar as part of the Grounding Electrode System  
George Little  Offline
Member
Joined: Jan 2004
Posts: 1,489
Michigan USA
Based on the '05 NEC the wording in 250.50 states that "if present" all of the listed electrodes will be included in the GES. In some areas the re-bar os the foundation and or basement walls consist of numerous pieces of re-bar that are not tied together. If the bars are not 20 feet and => 1/2 in in diametr then they don't qualify as an electrode and would not be included in the GES. It's only the larger projects where engineering spec out the re-bar and the tying together that we are fased with using the re-bar as an electrode. Since the State of Michigan is just now adopting the '05 NEC I wonder what the rest of the areas are doing? Is there any wording in the building codes that would have the builders tying the re-bar together to form an electrode?


George Little

2017 / 2014 NEC & Related Books and Study Guides

#168737 - 09/13/07 04:06 PM Re: Re-Bar as part of the Grounding Electrode System [Re: George Little]  
renosteinke  Offline
Cat Servant
Member
Joined: Jan 2005
Posts: 5,316
Blue Collar Country
I'm a bit confused; I don't think I have ever seen rebar or even mesh that was not tied together. A simple piece of tie wire holding the pieces in alignment counts ... there's no need for anything fancier.

I have seen isolated bits used when a repair or change was made to an existing pour .... and I've never seen those connected to the existing bar.

I don't think you HAVE to tie the rebar to the GEC, unless that rebar is accessible. For a Ufer, a length of copper wire will suffice - and it need not be in contact with th rebar. The rebar spec only applies, as I understand it, if you wish the rebare alone to be the "Ufer," without any copper wire.

Maybe I'm just confused ...


#168741 - 09/13/07 08:10 PM Re: Re-Bar as part of the Grounding Electrode System [Re: renosteinke]  
wire_twister  Offline
Member
Joined: Jul 2007
Posts: 265
Georgia USA
In my part of the world as of jan. 2007 all new construction must have a piece of the rebar brought above grade, it must be tied to the bar in the footing/slab,and must be bonded to the GEC or the electrode itself with no smaller than a 6 awg solid copper wire by approved clamp or CAD weld. I have to do one tomorrow for a garage addition on the opposite end of house from service, 85 feet away. Homeowner will not be happy!!


Jimmy

Life is tough, Life is tougher when you are stupid

#168742 - 09/13/07 08:17 PM Re: Re-Bar as part of the Grounding Electrode System [Re: renosteinke]  
George Little  Offline
Member
Joined: Jan 2004
Posts: 1,489
Michigan USA
Reno- The '02 NEC said "if available" and the feeling was that if it was not exposed it was not available. The '05 NEC says "if present" so this makes it mandatory to include it as an electrode and include it with any other electrodes that are present as the Ground Electrode system. My question had to do with the fact that if they weren't loug enough did we need to tie them together?

250.50 and 252.52(C)

Last edited by George Little; 09/13/07 08:18 PM.

George Little

#168744 - 09/13/07 08:59 PM Re: Re-Bar as part of the Grounding Electrode System [Re: George Little]  
HotLine1  Offline


Member
Joined: Apr 2002
Posts: 6,872
Brick, NJ USA
George:
Here in NJ:
Ufer ground is installed on the majority of new construction, resi & comm. 20' of rebar; 1 piece or tied, with #4 cu connected to it by an approved clamp or exothermic welding (Cadweld) It is inspected by the building inspector when footing is inspected. (Per NJ UCC)

Now...who installs the #4 & clamp...probably the mason.

If & when it's on the opposite side of building from service location..the EC extends it to the main disco or main panel; again with Cadweld or a crimp barrel.

I get to 'see' it on service inspection.

As to the actual rebar emerging from the concrete....thats a "NO-NO" opinion from the State DCA. Opinion is basically that the rebar will rust as it is exposed; as opposed to being encased in concrete.

Ufer ground and water pipe (when it's copper)and the grounding is done.

BTW, more and more resi is going with plastic piping throughout.

Stay safe


John

#168749 - 09/13/07 10:07 PM Re: Re-Bar as part of the Grounding Electrode System [Re: HotLine1]  
leland  Offline
Member
Joined: Aug 2007
Posts: 853
Lowell area, Ma. USA
So Wich one is supplemental? Ground rods or rebar?

My situation. My plan.

PSNH (utility) Requires the GEC to go to the meter can.

So I'm gonna' put 2 rods in and bond at the meter.
Then the rebar is going to go to the panel (inside right above the panel now)
All Plastic water. (PEX and well)

I see no problems, Do any of you?


#168754 - 09/13/07 11:47 PM Re: Re-Bar as part of the Grounding Electrode System [Re: leland]  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,126
Estero,Fl,usa
The Ufer has been part of the footer inspection in Florida for years.
This is an old picture (back when they were building houses) of the general practice.

http://members.aol.com/gfretwell/ufer.jpg


Greg Fretwell

#168762 - 09/14/07 09:35 AM Re: Re-Bar as part of the Grounding Electrode System [Re: gfretwell]  
Jim M  Offline
Member
Joined: Aug 2001
Posts: 457
Chestertown, MD, USA
I was under the impression that if a Ufer ground was used there was no need for any other grounds.

Can anyone confirm this?


#168763 - 09/14/07 09:47 AM Re: Re-Bar as part of the Grounding Electrode System [Re: Jim M]  
renosteinke  Offline
Cat Servant
Member
Joined: Jan 2005
Posts: 5,316
Blue Collar Country
You are more or less correct, Jim. You certainly do not need a ground rod, plate, etc.

You still need to bond the plumbing, though. The NEC, notorious for poor grammar, continues to refer to the water bond as a grounding electrode. It's pure semantics .... with a Ufer we're not relying on the plumbing as a GEC, but are instead concerned with clearing a fault to the plumbing.


#168774 - 09/14/07 06:09 PM Re: Re-Bar as part of the Grounding Electrode System [Re: renosteinke]  
Alan Nadon  Offline
Member
Joined: Mar 2005
Posts: 399
Elkhart, IN. USA
George,
We had this problem until we explained to the building inspectors that they were approving foundations that were not being built to the Building Code.
All the rebar is to be installed on blocks or chairs and tied together before the pour.
Dumping rebar into the foundation during the pour or having it stick out of the concrete into the earth is not the correct way to install the rebar.
On residential we have convinced most of the contractors to use 3/8 rod when they feel they must have rebar.
Those that use 1/2 must install it correctly and either bring it up inside in a dry space or have the copper connected before the pour.
This is definately a topic that needs to be covered at all Chapter and Section meetings of the Inspectors.
Even after I thought I knew it all I found out I didn't know it a lot.
On commercial jobs it is OK to go from the rebar to the building steel and building steel to the service. It does not have to go all the way to the service from the rebar.
The connection to the steel must be accessable.
The Code does not require a ground rod if the Concrete encased electrode is used However, the utility Co. usually will require Grd rods because the cannot see or confirm the Ufer ground.
If it was easy anyone could do it, and you couldn't charge $75 a hour. smile


Alan--
If it was easy, anyone could do it.

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