a copper rod is the best thing to use
as dude says,,the ground needs to be moist to allow current to flow/disperse- from the rod in the event of a citcuit fault-thus allowing a fuse/trip to disconnect the supply
here in the uk there is an area where the ground is chalk
this has a very high resistance especially when dry
and renders an earth rod uesless (i used 3 rods linked together to solve the prob)
rcd trips are essensial too, but some become faulty after a few years, so check them once a month by pressing th test button!
and use the correct trip rating (30 ma--milli-amp-)