Grounding Electrode Conductor

[don_resqcapt19]

While the last line says above 1100 Kcmil is 3/0 it did not say if it is applicable to single conductor only or multiple conductor only. Otherwise there will be no provision for 12.5%?

Please clarify what the 12.5% is for?

You can't just look at pieces and parts of the Table. You have to apply all of the information in the table. The text above the two left hand columns tells you the table applies to the total cross sectional area of the parallel conductors.

Section 250.66 applies only to the sizing of the grounding electrode conductor. There is nothing about 12.5% in that code section. Table 250.66 is used, by other code sections, for purposes other than the sizing of grounding electrode conductors. The 12.5% only applies when the table is used for those other purposes.