Re: grounding electrode conductor splice
Tom, in my line of buisness, telecom, we use Burndy Hy-Ground system products. They make "H" taps, "C" taps, rod clamps, etc for everything from # 14 upto 750 MCM, listed for use, and irreversible. We started using this system a few years ago to make life a little easier for electricians to get away from exothermic welds.
The down side is it does take special tools with dies to use the product. However in the telecom buisness, contractors are required to have the tools to work, they just have to buy the dies for them.