Its only recommended to fit mains smoke alarms on there own mcb, if they have no means of battery backup a Grade E system or the detector has no separate connection base. So with Aico, having its own termination base and battery backup to Grade D, power maybe supplied from either lighting circuit or its own mcb...choice is yours...Please guys remember these are Part 6 detectors for private dwellings and not for commercial shops, offices, pubs or Petrol stations, as Shell have just been fined for from H&S