Is it a Ground, or is it a Bond?

[David40]

Here is the scenario. A 400 Amp service with meter can outside and panel directly back to back. There is a 1/2 inch copper water line on the outside about 12' away. On the inside there is an 1-1/4" galvanized water main about 12' away from the panel. I want to run my 1/0 CU Grounding Electrode Conductor straight down out of the meter can to the ground rod. Then on the inside I want to run the water bond to the 1-1/4 water main from the panel. The question is, what size wire should be used to bond the water system? There seems be a disagreement about this among people I know. Personally I think it should be considered an equipment ground based upon the 400 amp Main Breaker, which would be #3 CU in this case, but others tell me it should be 1/0 CU like the Grounding Electrode Conductor, based upon the size of the 400 MCM Service conductors.
Would appreciate anyone's thoughts on this.
Thanks

 

[roger]

Have you read read 250.104(A)?

Roger

 

[Buck Parrish]

Here is the scenario. A 400 Amp service with meter can outside and panel directly back to back. There is a 1/2 inch copper water line on the outside about 12' away. On the inside there is an 1-1/4" galvanized water main about 12' away from the panel. I want to run my 1/0 CU Grounding Electrode Conductor straight down out of the meter can to the ground rod. Then on the inside I want to run the water bond to the 1-1/4 water main from the panel. The question is, what size wire should be used to bond the water system? There seems be a disagreement about this among people I know. Personally I think it should be considered an equipment ground based upon the 400 amp Main Breaker, which would be #3 CU in this case, but others tell me it should be 1/0 CU like the Grounding Electrode Conductor, based upon the size of the 400 MCM Service conductors.
Would appreciate anyone's thoughts on this.
Thanks

If the 1-1/4water main has 10' or more of contact with the ground then it to is a grounding electrode. And need s to ground the service with in 5 feet of where it comes out of the ground.

 

[augie47]

If, as Buck says, if you have 10ft or more of piping in the ground, then follow 250.52(A)(1). If you don't have 10 ft in the earth, then 250.104 is your guide.
You might want to look at 250.66(A) in regard to your ground rod also.

 

[erickench]

It would be a 1/0 CU based on the size of the service entrance conductors. See NEC table 250.66.

 

[Volta]

And you are able to limit the size to the ground rod to a #6 cu per 250.66(A).