I have tried using my rotary hammer to drive ground rods but it is too slow for me. I use a Bosch demolition hammer which works great. Hilti makes great tools but since it sound like you’re not going to be using this tool that frequently you might want to consider getting both a rotary hammer and 20-30lb demolition hammer from another manufacture for about the same price. I haven’t priced these tools recently but I would guess you could get the demolition hammer for around $800 and a decent rotary hammer for $400. The demolition hammer will work much better for the ground rods, breaking concrete and trenching with a clay spade. The large rotary hammers can do pretty well for all of these things but they are very heavy to use for drilling.
Curt
