Service grounding

[kwired]

In questioning the largest SEC, we also have to consider the conductor size feeding the meter, which has yet to be answered.

true, and it very well may be less than the two 4/0 conductors entering the building - especially if it is a POCO installed conductor. Many POCO around here will run 350 aluminum to such a service (although that still ends up giving you same size grounding electrode conductor according to 250.66).

 

[infinity]

The two 4/0 are not parallel but separate service entrance conductors. As I stated earlier, you'd use the sum (423200cmils) to size a common GEC and/or use 4/0 to size individual GEC's.

In questioning the largest SEC, we also have to consider the conductor size feeding the meter, which has yet to be answered.

Since you said a common GEC could be #2 or #1/0 Al I thought that you already knew.