Here is what my electrician said about ground rods:
I have been able to drive ground rods through anything but solid rock
using a large Bosch roto hammer with a ground rod driving attachment.
The roto hammer is set on hammer only and the ground rod attachment
must be used to avoid damage to the roto hammer. The roto hammer
is the largest Bosch makes and costs about $1,000.00. The ground
rod driver attachment costs about $70.00. Hope this helps.
Tom; NEVARI (Electrician)"
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