Grounding electrode system for a new building

[arentsch]

My firm has been contracted to provide the electrical engineering and design for a new building within an existing manufacturing plant. This new concrete building will be constructed on top of an existing concrete foundation. I am currently designing the grounding electrode system which brings me to this question.

250.52(A)(1)Metal underground water pipe does not exist.

250.52(A)(2) Metal Frame of the Building or Structure does not exist, building is concrete.

250.52(A)(3) Concrete-Encased Electrode exists, but is not accessible without disturbing existing concrete

250.52(A)(4) Ground Ring does not exist, however an existing ground ring for an adjacent building does exist and is within about 6' of the existing concrete pad.

250.52(A)(5) Rod and Pipe Electrodes do not exist

250.52(A)(6) Plate Electrodes do not exist


Can I use the existing adjacent building ground ring for this new building's grounding electrode system? or does the ground ring need to encircle the building to qualify as 250.52(A)(4)?

All feedback is appreciated.

Thanks.

 

[infinity]

So this is a new building with an existing foundation? Since there is no metallic water pipe two ground rods are all that are required.

 

[bphgravity]

You need to read section 250.50. If none of the electrodes described in 250.52(A)(1) through (A)(6) exist, one or more of the types in 250.52(A)(4) through (A)(6) shall be installed...

I say no to your second question regarding the ground ring.