I don't know your soil. I work in a clay Gumbo soil in Houton, Tx.
The way I install ground rods, I have 6 in a 1x3 meter square, is to
take a water hose and soften the soil a bit, then just start pushing the
rod a little, then lift it out of the hole, fill with water and repeat.
Don't go over 4 or 5 inches at a time making sure the water lubricates
the hole and rod. This takes about 30 minutes, don't use to much water,
you don't want to wash the hole out.
If this doesn't work build a driver for the rod, to do this take a peice
of steel or iron pipe about 4' long, put a cap on one end, slip over the
ground rod and use this to drive the rod, when you get to the 4' level
you can use a shorter piece of heavier pipe, or a real good friend and a
large hammer. I dig a hole and bury my rods complete, along with the
ground wire just for mowing and tripping reasons, in fact if I can't get
the rod clear in, I cut if off with a torch. I also Braise, not solder
the ground wire and use #4 fine strand wire.
From: tigger-at-prairienet-dot-org (Sean E. Kutzko)
I was skeptical with this ground rod installation tip, until I tried it
out. It REALLY does work:
Dig a little hole (say 6") where you want the rod to go in place. Get a
large bucket of water and fill the freshly-dug hole with it. Jam the rod
into the water-filled hole. Lift out and jam back in. Repeat as needed.
The secret here is to make sure the hole for the ground rod is kept VERY
wet. This way, the water is doing all the work for you. I slapped an
8-footer into the ground in 5 minutes this way; no sledge hammer needed.
Depending on the type of soil you have, you might need a sledge for the
last foot or so. Once you hit it with a sledge, the back-and-forth
jamming process won't work any more, so be sure you REALLY want to use a
sledge on it.
BTW, get that sucker as far into the ground as you can. If it's an
8-footer, then sink it 7 and a half feet.
From: HarrisR-at-yvax.byu.edu (Richard Harris)
I drove my 8' ground rod using a fence post driver. The post driver
that I used is one that is made to drive T type metal fence posts.
This allowed me to drive the post in about 6 feet or so and then I used
a sledge to finish driving the rod. I would drive it in all the way
and make sure that it is at least 6 inches below grade. I hope yours
goes in better than mine. I have very rocky soil and it took me 2-3
hours. I have put rods in soil without rocks in 10 minutes.
good luck and 73