According to Takoma Park Volunteer Fire Department Postmaster :
Chris Lewis wrote:
Actually, one can show that very easily: note (A) above:

"Electrodes PERMITTED for Grounding".

W Tom's position is that you can forgo connecting to an underground
metal water pipe if you have another electrode. Did you read the first
section of the US NEC that I quoted?

You're quite right. Oops. Reading too fast.

I certainly don't subscribe to the "you don't have to connect underground
metal water pipe" to the grounding system (as electrode _or_ as bonding)
theory.

I was merely trying to point out, (as commented on by others), that in the
end result, it doesn't matter, because it _has_ to be bonded/equivalently
anyway. As do all other significant metallic building structure - ie:
ducting, metal framing.

Yes, there may be quibbles about "boundary issues", such as metal piping
ending right at the building envelope. But that would happen anyway,
such as unconnected-to-the-building water mains going beside the building.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.