I have a 4" metal sprinkler main entering a building under construction. It needs to be connected to the grounding electrode system with a 2/0 conductor. None of the catalogs I have show a grounding clamp of that size. The flange bolts on the sprinkler main are a much larger diameter than the mounting hole on a 2/0 lug. Any suggestions as to other methods of attaching the 2/0 conductor?