It has been brought to our attention by a customer that a previous EC had used a copper split bolt connector for connecting the gec to a 3/4 copper ground rod. I have not been able to find a mfg that rates a split bolt for this purpose.
I too have seen this done. The split bolts are not listed for this purpose, and should be red-tagged. I assume the reason is the electrician was out of acorn clamps.