In the 2003 IBC Section 712.3.1.2:
"Through penetrations shall be protected by an approved penetration firestop system installed as tested in accordance with ASTM E 814 or UL 1479, with a positive pressure differential of 0.01 inch of water and shall have an F rating of not less than the required fire-resistance rating of the wall penetrated."
All of which means the inspector must approve the firestop system. Most all inspectors will accept any UL assembly if installed per the UL instructions.
