based off version NEC 2014 concrete encased electrode grounding electrode conductor size

[hhsting]

I have NEC 2014 section 240.64(F)(3) arrangement where conductor from main service disconnect neutral bar goes to external ground bus bar. From bus bar one conductor goes to grounding electrode. Please see attached sketch. The incoming service conductors are 5 sets of 600kcmil

In the attached sketch conductor from external busbar to concrete encased electrode labeled “size” in attached sketch what size should it be based on NEC 2014? #4awg or 3/0 awg? I looked at NEC 2014 section 250.66(B) but its confusing I have bonding jumper NOT grounding electrode conductor according to NEC 2014 section 250.64(F)(3) from external bus bar to grounding electrode so not sure if NEC 2014 section 250.66(B) applies or not.

 

[Dennis Alwon]

It is confusing because 3/0 is the size needed for a grounding electrode conductor however, the code states that a #4 is all that is needed for a concrete encased electrode. Similarly and #6 is all you need to a ground rod no matter what the service size.

 

[augie47]

and, IMO, based on 250.64(C) you have a "grounding electrode conductor tap" and not a bonding jumper and. as Dennis states, #4 to the CEE

 

[hhsting]

and, IMO, based on 250.64(C) you have a "grounding electrode conductor tap" and not a bonding jumper and. as Dennis states, #4 to the CEE

Not to be bad or anything but....

NEC 2014 section 250.64(F)(3): “Bonding jumper(s) from grounding electrodes shall be permitted to be connected to an aluminum or copper busbar....”

So i dont follow how are they not bonding jumpers?

 

[augie47]

You are likely correct. I read too quickly,. The two sections are so similar. Potato, po-ta-to, the #4 is all that's needed.

 

[hhsting]

You are likely correct. I read too quickly,. The two sections are so similar. Potato, po-ta-to, the #4 is all that's needed.

Looks like not sure:

NEC 2014 section 250.53(C) Bonding Jumper. “The bonding jumper(s) used to connect to the grounding electrodes together to form grounding electrode system shall be installed in accordance with 250.64(A),(B) and (E), shall be sized in accordance with 250.66...”

NEC 2014 section 250.66(B) says sole grounding electrode conductor to concrete encased electrode but does Not saying anything about bonding jumper should be #4 awg concrete encased electrode. Which then leaves one way #3/0 table 250.66


Cant say I didn’t do my homework huh


Unless I missed something here

 

[Greentagger]

Agreed #4 to the CEE and 3/0 from service disconnect to grounding electrode tap buss.

 

[hhsting]

Looks like not sure:

NEC 2014 section 250.53(C) Bonding Jumper. “The bonding jumper(s) used to connect to the grounding electrodes together to form grounding electrode system shall be installed in accordance with 250.64(A),(B) and (E), shall be sized in accordance with 250.66...”

NEC 2014 section 250.66(B) says sole grounding electrode conductor to concrete encased electrode but does Not saying anything about bonding jumper should be #4 awg concrete encased electrode. Which then leaves one way #3/0 table 250.66


Cant say I didn’t do my homework huh


Unless I missed something here

Above post was saying external bar to CEE #3/0 awg Not #4 awg

 

[augie47]

Shocking but yep you did !!
I'm comfortable with the #4 and I;'m sure the answer is hidden in thee somewhere... but in Art 250 its often the needle in the haystack.

 

[don_resqcapt19]

Your work is typically designed work, I would be very surprised if the design documents permit the minimum size per the NEC.

That would be rare in my experience, as the design spec very often calls for a full size conductor to all grounding electrodes, no matter what the code may permit.

 

[Canton]

Your work is typically designed work, I would be very surprised if the design documents permit the minimum size per the NEC.

That would be rare in my experience, as the design spec very often calls for a full size conductor to all grounding electrodes, no matter what the code may permit.

Yup, Ben on some crazy jobs where the engineer (over engineering) wanted 500kcmil GEC cadwelded to ground rods. I told him ill get right on it as soon as he finds me the mold.

 

[don_resqcapt19]

Yup, Ben on some crazy jobs where the engineer (over engineering) wanted 500kcmil GEC cadwelded to ground rods. I told him ill get right on it as soon as he finds me the mold.

Cadweld has those molds for 5/8", 3/4" and 1" ground rods in multiple connection configurations.

https://www.erico.com/category.asp?category=R2751&parameters=VAB8AEEAMwA1ADMAXwAxADMAMwA5ADUAMwB8AFQAQQAyADMAMgA1,VAB8AEEAMwA3ADUAXwAxADMANgAxADkAMwB8AFQAQQAwAA2

 

[Canton]

Y

Cadweld has those molds for 5/8", 3/4" and 1" ground rods in multiple connection configurations.

https://www.erico.com/category.asp?category=R2751&parameters=VAB8AEEAMwA1ADMAXwAxADMAMwA5ADUAMwB8AFQAQQAyADMAMgA1,VAB8AEEAMwA3ADUAXwAxADMANgAxADkAMwB8AFQAQQAwAA2

Ya, this was years ago. Doesn't surprise me that they are available now.

 

[don_resqcapt19]

Y

Ya, this was years ago. Doesn't surprise me that they are available now.

Probably because a lot of engineers specify very oversized EGCs.

 

[electrofelon]

I think your answer, that the reduced size conductors allowed for CEE and rods apply when they are bonding jumpers and not GEC"s, is found in 250.53(C) which sends you to 250.66 (note 250.66, NOT table 250.66).

I think the wording in 250.66 A and B should be changed to just say "conductor" or "GEC or bonding jumper" to make it a little more clear.