If you google the term "electrical ground", or "equipment ground", you 
will be reading for at least the next ten years.

The push now days is to have everything tied to the electric utility 
ground which is located at the point where the electrical service 
enters your house. If your telephone and cable services are up to 
current electrical codes, that is where they are also grounded.

For some radio installations, this becomes somewhat challenging, not 
to mention expensive. It usually involves multiple ground rods between 
your radio shack and the service ground, with heavy copper tying them 
together, and then more copper tying that network to the service 
ground.

This network includes the rods around your tower.

Mike Duke, K5XU
American Council of Blind Radio Amateurs