National Electrical Code Articles and Information

1. [250.98]. Make them electrically continuous.
    

2. [250.100(D)]. Size it per Table 250.122.
    

3. [250.100(E)]. It can be in either location. What's critical is it's limited to 6 ft in length if outside. If it's inside, it must comply with 250.119 and 250.148.
    

4. [250.104]. It has to be bonded. The bonding requirements are fairly lengthy, so read them carefully. Don't assume that the water pipe is bonded or grounded. Many people have been killed due to making this assumption.
    

5. [250.106]. You connect them. That is, you bond them. The last thing you want is a flashover from the lightning protection system to something metallic in your building electrical system. You'll find further details in NFPA 780, Standard for the Installation of Lightning Protection Systems and in the Lightning Protection Institute's LPI-175, Standard Practice for the Design - Installation - Inspection of Lightning Protection Systems.