https://www.electrical-contractor.net/The_Store/EX/382152.htm This is the meg tester I use.
I do mostly cell tower sites and we must show under 5 ohms resistance and it works great.
Our AHJ requires 2 ground rods, water bond and building steel if available. Also Ufer bond on new construction in place of the 2 ground rods, but no proof of resistance test
