Multiple grounding electrodes -- connecting wire sizes

[fmtjfw]

The following is from a code panel yesterday:

My grounding electrode system consists of a water pipe, a UFER, and a ground rod. My service conductors are 500kcmil copper. Can I run a 1/0 CU grounding electrode conductor to the water pipe, then a #4 copper conductor from the water pipe to the UFER, then a #6 copper from the UFER to the ground rod?

The answers were yes and no. What do you guys think?

 

[jumper]

What was the reason for the no, sounds legal.

 

[petersonra]

The following is from a code panel yesterday:

My grounding electrode system consists of a water pipe, a UFER, and a ground rod. My service conductors are 500kcmil copper. Can I run a 1/0 CU grounding electrode conductor to the water pipe, then a #4 copper conductor from the water pipe to the UFER, then a #6 copper from the UFER to the ground rod?

The answers were yes and no. What do you guys think?

My answer would be yes. However, the #6 would have to be protected in some way.

 

[jumper]

My answer would be yes. However, the #6 would have to be protected in some way.

I would imagine that from an UFER to a rod would most likely be buried in dirt and not subject to damage.

 

[fmtjfw]

Engineer's answer

Engineer's answer

What was the reason for the no, sounds legal.

The no answer came from an engineer on the panel. He said that all conductors needed to be 1/0 since 250.66(A)&(B) both stated "that portion of the conductor that is is sole connection to the grounding electrode" invalidated the two smaller conductor exceptions. Basically that the #4 conductor had to carry not only the current to the UFER but also to the ground rod. He didn't extend that argument to the 1/0 since the table said it was sufficient for any GEC.

His argument depends on what "sole" means.

 

[jumper]

The no answer came from an engineer on the panel. He said that all conductors needed to be 1/0 since 250.66(A)&(B) both stated "that portion of the conductor that is is sole connection to the grounding electrode" invalidated the two smaller conductor exceptions. Basically that the #4 conductor had to carry not only the current to the UFER but also to the ground rod. He didn't extend that argument to the 1/0 since the table said it was sufficient for any GEC.

His argument depends on what "sole" means.

The fact that since you have a water pipe and UFER GES in place means that the whole rod connection(s) is nothing but extra.

EE is wrong IMO. I believe the purpose of this section is more in line with something like that you cannot run a #4 to a UFER and then then a larger jumper, ie: #2 to a ground ring, and be compliant.

 

[petersonra]

I would imagine that from an UFER to a rod would most likely be buried in dirt and not subject to damage.

the dirt could well be the protection means IMO.

 

[petersonra]

The no answer came from an engineer on the panel. He said that all conductors needed to be 1/0 since 250.66(A)&(B) both stated "that portion of the conductor that is is sole connection to the grounding electrode" invalidated the two smaller conductor exceptions. Basically that the #4 conductor had to carry not only the current to the UFER but also to the ground rod. He didn't extend that argument to the 1/0 since the table said it was sufficient for any GEC.

His argument depends on what "sole" means.

I think he does not understand English very well.

 

[jumper]

the dirt could well be the protection means IMO.

In that case, I agree.