Health care occupancies shall conduct unannounced fire drills, but not less than one (1) drill per shift per calendar quarter that transmits a fire alarm signal and simulates an emergency fire condition. When fire drills are conducted between 9:00 p.m. (2100 hours) and 6:00 a.m. (0600 hours), a coded announcement shall be permitted to be used instead of audible alarms. False alarms may be used (up to 50% of total drills) if all elements of the fire plan are exercised. Business occupancies shall conduct at least one unannounced fire drill annually per shift.