Fire Alarm Service (FAS) Minimum ChargeFire alarm systems can complex and rely on a power supply to function correctly as such routine servicing will help maintain this life critical system and ensure that it will always operate when required to do so and to help prevent false alarms. Under the Regulatory Reform (Fire Safety) Order 2005 it is a legal requirement that all fire alarms are maintained on a regular basis and an appropriate service certificate stating the condition of the alarm