"I had put two of these in the ground and decided to add a third to make a 12ft earth rod. You need a joiner and a driving nut even for one rod, and after the third rod these were showing signs of having been hit hard and often with a sledgehammer. But they are cheap enough and this is a good system if you want a low-resistance earth. Shame the rods were out of stock for a while."
"Purchased four of these for a new TT earth system, having found we had a very poor TN-S supplier earth, which the supplier refused to rectify. Used two rods connected together 8ft apart. Reasonably easy to hammer into the ground on wet clay based soil."