GEC size to concrete encased rebar

[bassphisher]

I know that this subject has been beat to death but please bear with me.
In this part of the country we are stubbing out a piece of rebar through to floor in the basement or out of the top of the poured wall and then connecting a GEC to this stub out.
My question is this:
Can the GEC be smaller than #4 copper when the service entrance conductors are #1/0 copper and smaller and a rebar is stubbed out as mentioned above,250.66(B) says that it shall not be required to be larger than #4 copper but it does not say that you can use table 250.66 for GEC sizing when the service entrance conductors are smaller sizes,and the GEC is connected to a concrete encased rebar.
In other words can we use #6 copper connected to a 1/2 20' rebar encased in concrete.The rebar is the electrode and the wire is the GEC for a service that the service entrance conductors are #1 copper

 

[jwelectric]

Re: GEC size to concrete encased rebar

250.66 Size of Alternating-Current Grounding Electrode Conductor.
The size of the grounding electrode conductor of a grounded or ungrounded ac system shall not be less than given in Table 250.66, except as permitted in 250.66(A) through (C).

 

[friebel]

Re: GEC size to concrete encased rebar

250.66(B) Connections to Concrete-Encased Electrodes.
The grounding electrode conductor shall not be required to be larger than #4 Copper wire.

 

[ryan_618]

Re: GEC size to concrete encased rebar

Yes, you may use 6 AWG to connect to the rebar if your service entrance conductors are 1 AWG.

 

[friebel]

Re: GEC size to concrete encased rebar

To: Ryan 618, Would you please state the section of the NEC that will allow you to use #6 copper on a Concrete-Encased Electrode.
I was stating Section 250.66(B) that states #4 Copper wire.

 

[jwelectric]

Re: GEC size to concrete encased rebar

Originally posted by friebel:
To: Ryan 618, Would you please state the section of the NEC that will allow you to use #6 copper on a Concrete-Encased Electrode.
I was stating Section 250.66(B) that states #4 Copper wire.

Look at my post above and you will see that it states "not smaller than table 25.66.

250.66(B) states "not larger than"

The question was could it be smaller than #4

 

[spsnyder]

Re: GEC size to concrete encased rebar

I read it that the max. size is not required to be over No. 4. A No. 6 is allowed. If the table required a No. 2 the provisions below the table would usurp the table and a No. 4 would be allowed.

 

[jwelectric]

Re: GEC size to concrete encased rebar

Originally posted by spsnyder:
I read it that the max. size is not required to be over No. 4. A No. 6 is allowed. If the table required a No. 2 the provisions below the table would usurp the table and a No. 4 would be allowed.

I agree with this post

 

[tom baker]

Re: GEC size to concrete encased rebar

There is a difference between table 250.66 and section 250.66. A reference to the table results in a full size GEC while the section is for the GEC's to specific electrodes, and will be a change from the table.

 

[pierre]

Re: GEC size to concrete encased rebar

In general, the table as per section 250.66 is how to size the GEC. There are provision in the language of 250.66 that permit otherwise in (A)-(C).

(B) permits the size to be no larger than 4 AWG if the provisions of that subsection are met.
So yes it can be smaller as per the table.

 

[George Stolz]

Re: GEC size to concrete encased rebar

Originally posted by friebel:
I was stating Section 250.66(B) that states #4 Copper wire.

It's a common misperception that the only size wire you can use for a GEC with a CCE is 4 AWG. It can sometimes take half a bottle of Advil to get the record straight.

Read this recent memo from a local inspection agency in my area, declaring the major changes of the 2005 NEC:

Section 250.50 - Concrete encased electrode or UFER ground is now required for all buildings.
Three different methods may be used to attain compliance.
</font>

• <font size="2" face="Verdana, Helvetica, sans-serif">Method 1: #4 copper clamped to a 20 ft long piece of reinforcing in the footing. Reinforcing must be encased in at least 2 inches of concrete. Reinforcing must be supported at time of inspection.</font>
• <font size="2" face="Verdana, Helvetica, sans-serif">Method 2: Minimumof #4 copper encased in the footing with a minimum of 2 inches of concrete. The #4 must be supported at time of inspection.</font>
• <font size="2" face="Verdana, Helvetica, sans-serif">Method 3: #4 copper clamped to a vertical reinforcing bar that extends to the bottom of the foundation wall and ties to a horizontal reinforcing bar with a minimum lap of 30 inches. The vertical reinforcing bar shall protrude a minimum of 12 inches above the top of the foundation wall. The vertical bar shall be encased in a minimum of 2 inches of concrete.</font>

<font size="2" face="Verdana, Helvetica, sans-serif">

I take issue with this: "Section 250.50 - Concrete encased electrode or UFER ground is now required for all buildings." They artfully neglect to mention "where it is present."

Method #1 clearly misreads 250.66(B) as saying that the GEC must be 4 AWG, regardless. That's not correct.

I'm still not sure if they have amending authority. This entity is a sort of freelance inspection department that has a 50 mile radius they hop and jump through. I think I'll look them up after a bit.