Frank: I guess it depends on who is asking, or requesting the bonding info. The electrical contractor has the NEC responsibility in new construction, and major renovation work here. THe iron workers make-up "tight" connections, and we bond to the main beams usually. If the client, architect, engineer, etc. specs or requests, we install jumpers as specified.
#14353 - 09/20/0206:22 AMRe: Structural metal member
Frank, You can get IAEI Soares book on grounding for a very thorough explanation. If the steel is attached to bolts, in concrete, underground, it is basically considered grounded. It can get more complicated and I suggest a good read of Soares.
All steel needs to be bonded to the neutral though, don't forget that.
jumpers do not need to be attached for continuity, only welded or bolted together, and that usually is accomplished by the steel guys.
#14355 - 09/20/0207:23 AMRe: Structural metal member
Thank you for responses. I'm meeting with an Electrical Engineer at job site this morning. Briefly, a separtely derived system is going to be installed on the eighth floor of our City Hall Building for County wide Court system. It is going to provide power for a computer room. Running a grounding electrode conductor to the water meter in the basement is one option. Of course a ground rod must be driven. The other option is to use the structural building steel which does not require a driven ground rod.
#14356 - 09/20/0208:37 AMRe: Structural metal member
The Electrical Engineer deemed the structural metal not effecively grounded. He wants to use the metal water pipe. Wouldn't 250.53(D)(2) apply. ie. Supplemental electrode required, or doesn't that apply for separately derived systems?
#14358 - 09/20/0203:33 PMRe: Structural metal member