I need to ground an extension to an existing building structure which does not have an existing ground ring. The structure itself is inter-connected throughout but will not satisfy 250.52(A)(2) as a grounding electrode; am I correct in assuming In most cases, the steel can be made to qualify by connecting it to a ground rod & tying into the existing steel structure ?...................the building is under 60 feet in height and does not require a ground ring.
Many thanks in advance for all replies.
I agree with Dennis on this one. If the existing building already has an established GES then simply adding on to the existing building, interconnecting them as you described would still constitute a single building and do not see the need to do anything. I am not sure I understand the "ground ring" reference since they are never required but are permitted.
As Dennis (old man) stated, in order to have any of the building steel qualify as anything in terms of a grounding electrode, you would need to meet the requirements of 250.52(A)(2) and from what I gather than is not possible based on your desires and statements.
Now I will assume (bad to do on this forum) you are talking about Section 250.68(C)(2) in terms of using the building steel as part of the grounding electrode system and/or a grounding electrode conductor. It appears you are asking can you place a ground rod on the new portion of the building, use the structural steel of the building [250.68(C)(2)] and be done with it...well that wont work if the actual structural steel frame is not actually connected to any GES in the first place.....you would be the only one to actually know that because we are assuming here.
But at the end of the day, it sounds like you do not have anything being used as structural steel or any connection to it at all....thus chances are 250.68(C)(2) would not assist you and as Dennis stated I am not convinced you need to do anything with the extension portion of the building since it is connected to the original building.
Keeping in mind that if any of the "structural steel frame" is likely to become energized....(not feeling like debating that concept today) then bonding per 250.104(C) might rear it's head.....but alas, with all that verbiage I just stated......I will go with Dennis "The Old Man" on this one.
Just my thoughts on it.....Now if the extension is being treated like a separate building and qualifies as such.....then it may have it's own service and so on then the rules here change a bit...or your local AHJ grants you something under 230.2 then we will open up a new discussion on that....
