Footing on an addition?

[celtic]

I'm doing a small (12x12) addition on a SFH...all wood structure. The GC asked me if the rebar in the footings needs to be grounded back to the panel. I asked the GC "Why? What's the danger? It's a wood structure". He replied he was required to do this in another town.

I personally don't see the need nor requirement to run a #4 from the rebar back to the panel.

The service will be changed out on this project, so 2 ground rods will be driven along with a connection to the metal water pipe.

Can anyone tell me why such a requirement may be required?

 

[macmikeman]

I would say that because you are changing out the service, and installing a new addition, you must use all of the grounding electrodes that are present when installing your new gec. The rebar in the new footing is required as one of the electrodes for new installations. If you were just replacing the service and not wiring an addition that has rebar in the footer then maybe not required.

 

[gndrod]

Celtic,
Changing out the panel is key in saving the cost of ground rods clamps, extra jumper and possibly a long run of the GEC relative to where the new panel and stemwall will be located. In practicality, I have used rebar as the UFER since 1970's with no problem from the AHJ or the GC's...most of them stubbed up an end under the panel location without additional cost. Unless the AHJ has different requirements, I would stub one up regardless of it being used or not, just in case. The stubbed up rebar labor cost is nil compared to the material cost and time it takes to drive rods. JMO&E, rbj

 

[infinity]

What size rebar is going in the footing? If not 1/2" or larger no CEE is required.

 

[celtic]

Thanks guys.

I see where the requirement is: 250.52(A)(3)
A #4 on their combination of 3/4" and 1/2" rebars was installed. As I was not onsite today, the GC and mason installed the wire prior to the pour...that pour should be done by now.

I missed the inspector, but the GC asked him the same questions I had:

Q: What's the point?
A: I don't know..I'm just here to enforce the code.



While I recognize the Articles (250.50 and 250.52(A)(3) )...what is the point?

Of note....although possibly not of any consequence...this commentary follows 210.50 in the '02 NECH:

Formal Interpretation 78-4
Reference: Article 250.50
Question: Is it the intent of 250.50 that reinforcing steel, if used in a building footing, must be made available for grounding?
Answer: No.
Issue Edition: 1978
Reference: 250-81
Issue Date: March 1980

This commentary is NOT in the '05 NECH...and may have been rendered void by changes for '02 - '05:
210.50 '02:

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.

210.50 '05:
Grounding Electrode System.

All grounding electrodes as described in 250.52(A)(1) through (A)(6) 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)(7) 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.

The change from If available toAll grounding electrodes...that are present, seems (to me) to void the Formal Interpretation 78-4.


Inspite of all this..I still fail to see "What's the point?"

 

[celtic]

Celtic,
... I would stub one up regardless of it being used or not, just in case. The stubbed up rebar labor cost is nil compared to the material cost and time it takes to drive rods. JMO&E, rbj

Are you saying the rebar could be used instead of the ground rods(250.52(A)(5) / 250.53(G) / 250.56 / 250.58 )(?

 

[electricmanscott]

The way I read it is you would have to use the rebar, and no rods are required.

 

[infinity]

The way I read it is you would have to use the rebar, and no rods are required.

I agree. For the same reason that you wouldn't have to use the CEE if the rebar were smaller than 1/2".

 

[celtic]

The way I read it is you would have to use the rebar, and no rods are required.

I agree. For the same reason that you wouldn't have to use the CEE if the rebar were smaller than 1/2".

Thanks again guys.

 

[don_resqcapt19]

Celtic,

The change from If available toAll grounding electrodes...that are present, seems (to me) to void the Formal Interpretation 78-4.

It does and that was the intent of the change.
Don

 

[bphgravity]

I agree with all the previous posts and would also require a new mono-slab / foundation with a code recognized CEE installed to be run to the new service.

 

[ryan_618]

I also agree with the others. There is no exception in 250.50 for wood buildings.

 

[hillbilly]

Since we're discussing Ufers, I've got a question.

If a (bare) #4 copper conductor extends into a concrete footer (approx 5') and is bonded to the footer re-bar... does that make the copper conductor part of the grounding electrode?

The reason I ask, is that I was questioned about using a split bolt to connect the GEC from the main panel to this copper wire.

The inspector thought that the connection should be irreversable, I disagreed.

My position is...that since a portion of the #4 is buried in the concrete, all of it is part of the grounding electrode.
I ran un-spliced from the main to this conductor/GE and I could use any listed connector to join the two. (250.70).

It was passed after some discussion, but I wonder.

Any thoughts?
steve

 

[rcarroll]

IMO, at least 20' of #4 is required for it to become a grounding electrode, 250.52(3). If you only have 5' of #4 to rebar, I'd say it is a grounding electrode conductor & irreversible connectiion required.

 

[celtic]

The reason I ask, is that I was questioned about using a split bolt to connect the GEC from the main panel to this copper wire.

The inspector thought that the connection should be irreversable, I disagreed.

Does a split bolt meet the critera in 250.70 (and also 250.8)?

... by exothermic welding, listed lugs, listed pressure connectors,
listed clamps, or other listed means.

...taking you back to 110.3.
Is a split-bolt listed for this application?

 

[hillbilly]

Does a split bolt meet the critera in 250.70 (and also 250.8)?


...taking you back to 110.3.
Is a split-bolt listed for this application?

Well....I always thought that it was.
I know that it (the bolt that I used) is listed (UL) for joining (2) #4 copper conductors.
It's made of brass...don't know if it's cast or not.

Listed for grounding?....Don't know.

I have my (recent) doubts, that's why I posted.

thanks
steve

 

[celtic]

Well....I always thought that it was.
I know that it (the bolt that I used) is listed (UL) for joining (2) #4 copper conductors.

Is rebar made of copper?

 

[mayjong]

isn't a connection buried in concrete now "irreversible"?

 

[infinity]

IMO, at least 20' of #4 is required for it to become a grounding electrode, 250.52(3). If you only have 5' of #4 to rebar, I'd say it is a grounding electrode conductor & irreversible connectiion required.

I agree. 5' of conductor to the rebar would become part of the GEC. This installation doesn't have a metallic water pipe?

 

[hillbilly]

Is rebar made of copper?

I'm not talking about the connection to the re-bar, that's OK.
I'm talking about the connection of the (#4) GEC that runs from the panel to the other piece of #4 that goes into the footer.
I'm asking if the piece of #4 wire that goes into the footer is part of the grounding electrode and if I can connect to it with a (listed) split bolt?

I say yes to both.

steve