Size of GEC

[monkey]

Section 250-50 (99NEC) says "an unspliced GEC shall be permitted to be run to any convenient grounding electrode available in the grounding electrode system or to one or more grounding electrodes individually. It shall be sized for the largest GEC required among all the electrodes connected to it."
Section 250-66(a) says connections to made electrodes as permitted in 250-52(c) or (d) shall not be required to be larger than #6 copper.
Does this mean if you have a water pipe, ground rods or rebar you must use #4 (200A service) to all of them if it is one continuous GEC?
And if you run separate GECs does it mean you can run a #4 to the water pipe and a separate #6 from the buss to the rods or rebar?
Could this be why I only see Cadweld one shots for #6?
I am not sure if rebar qualifies as a "made electrode"
Thanks for any help.
Brian

 

[mclain]

Re: Size of GEC

Monkey
The requirement for a rebar type electrode. can be found in 250.52 (A)(3). If you connect to a concrete encased electrode. #4 AWG copper wire is required. And per 250.64 (F) all of the grounding electrode conductor would have to be #4 that go to your gounding electrodes. I am sure there is others who would read this section different.

 

[don_resqcapt19]

Re: Size of GEC

Brian,
The GEC must be sized for the grounding electrode that it is connected to. If have a 3/0 copper service, you could take a #2 to the water pipe, make a cadweld tap with #4 to the rebar and make a tap from the #4 with #6 to the ground rod.
Don

 

[dana1028]

Re: Size of GEC

Originally posted by don_resqcapt19:
Brian,
The GEC must be sized for the grounding electrode that it is connected to. If have a 3/0 copper service, you could take a #2 to the water pipe, make a cadweld tap with #4 to the rebar and make a tap from the #4 with #6 to the ground rod.
Don

Don - you mention making a 'cadweld' tap to the GEC.

Is not a split-bolt also permitted for this tap?

I ask because there are few who would accept a split-bolt for this application, yet...

George Flach, Electrical Contractor magazine, April, 2003 in an article entitled "Grounding Electrode Taps" indicates split bolts are allowed for taps to the GEC.

Also, Soares, 8th edition, pg. 118 - "...the tap conductor is required to be connected to the main GEC with a device that allows the main GEC to remain unbroken as the connection is made."

Fig. 7-8 (Soares, same page) actually shows a split-bolt as the connecting means for the tap.

 

[don_resqcapt19]

Re: Size of GEC

Dana,
The code is very clear that a split bolt is permitted to connect a GEC tap to multiple service disconnects. The issue of taps to multiple grounding electrodes is not as clear. I just prefer a cadweld connection for GECs, but the code does not say that irreversible connections are required.
Don

 

[dana1028]

Re: Size of GEC

thank you Don, I appreciate the feedback

 

[monkey]

Re: Size of GEC

Thanks but I am still confused. If 250-50 states the following: "an unspliced GEC shall be permitted to be run to any convenient grounding electrode available in the grounding electrode system or to one or more grounding electrodes individually. It shall be sized for the largest GEC required among all the electrodes connected to it." then doesn't that mean if you are using a water pipe and a ground rod you must use #4 to both???(200A). Or maybe it means #4 only if you go to the rods first and then the pipe? That makes more sense to me.
And then theres the issue of irreversible splices. I guess this refers to splicing sections of the same GEC together meaning a tap would not be required to be irreversible???
This section has always been a gray area for me and I appreciate you guys taking the time to help me out.
Brian