The coax shield should be grounded with a grounding block that is connected to the house electrical system ground with 10 gauge copper wire for electrical safety and to reject interference. For further compliance with the electrical code (NEC), the mast should also be grounded in a similar manner to drain any buildup of static charge, but the system will not survive a direct strike.
Satellite System Grounding
Part 2 - NEC Overview
Presented by Todd Humphrey
http://www.dbsinstall.com/diy/Grounding-2.asp
Todd Humphrey doesn't speak for the NFPA that publishes the NEC code, but he has some ideas that are helpful. The local electrical inspector has the final say if you are willing to get him involved. Some inspectors are more friendly than others; a local electrician could tell you.