Building Frame grounding

[dahualin]

I checked some electrical designs done by other electrical engineers. Those designs show the steel structure building have building frame groundings. The grounding detail shows one ground rod for each column. Only around two fifth columns of the builing have that kind of grounding and they are not connected to grounding electrode system. that means they are not bonding to anybody, they are alone. I don't think it is correct refer to Article 250.104.(C).

Any thought is welcome.

 

[cpal]

there is an argument that they should all be picked up but this seems to have been done for a specific reason??

250.50 Grounding Electrode System.
All grounding electrodes as described in 250.52(A)(1) through (A)(6) that are present at each building or structure served shall be bonded together to form the grounding electrode system. Where none of these grounding electrodes exist, one or more of the grounding electrodes specified in 250.52(A)(4) through (A)(7) shall be installed and used.

 

[don_resqcapt19]

David,
That is not an uncommon grounding design. As long as there is a GEC sized per Table 250.66 to the building steel to the serivce you are in compliance with the code, assuming that this is a metal frame building and all columns are interconnected by the beams and other structural members. This would not be a 250.104 installation. It would be a 250.52(A)(2) installation.
Don

 

[barbeer]

Could the steel of said steel building be the bond between electrodes?

 

[barbeer]

dang slow fingers!