if i run a 2/0 ground wire to the ground rod,how many ground rods do i install.do grnd rods have a specific size?mfg cannot answer this.i shouldnt have to run reststance tests untill i get enouge rods in. been too long. i used to know this.im getting too old i guess.rw

Per the NEC, the rod must be a minimum of 5/8" in diameter, {250.52(A)(5)(b)}you would never need more than two rods and a #6 for the GEC.

If you are trying to meet a performance spec, you would need to install as many as it takes to get to the resistance number set by the spec and a larger conductor would help.

Roger

[This message has been edited by Roger (edited 11-19-2005).]