Primary & Secondary Ground

[Dean83169]

In a commercial building which is Primary and which is Secondary for the service.
Would the cold water which extends 10' in the ground ( city main ), building steel, a # of ground rods driven through the slab into the earth; or would ANY of those be listed for primary and secondary in the code. If this is the case of using building steel, can you use the building steel with full size and then tap off the steel on the other side of the building to bond the cold water which would be your secondary.

 

[tom baker]

The NEC does not use the terms primary and secondary. The a grounding electrode listed in 250.52 is present it must be used.

However the code seems to list the GE in 250.52 (A) in order of preference.
But what you do is hit one electrode with a GEC sized per 250.66 and then you can interconnect from there. Building steel and water lines are both full sized GEC so there is no difference in the size.
GEC listed in table 250.66 are full size and GEC listed in section 250.66 have a reduction in size.

 

[steve66]

If you are asking which is the "supplementary electrode", the ground rods would be the supplementary. See 250.53(D)(2).

"A metal underground water pipe shall be supplemented by an additional electrode....".