560.7.1?
560.7.1 deals with many types of safety services. Some of which obviously need a separate supply. (e.g. Fire pumps, fire rescue service lifts, etc)
But we are talking about domestic smoke alarms here, typically LD3. In BS 5839-6 2004 , and the manufacturer's instructions, the following is stated:
The power supply for the Alarms should be derived from the public electricity supply to the dwelling. The mains supply to the Alarms should take the form of either:
(a) an independent supply at the dwellings main distribution board, in which case no other electrical equipment should be connected to this circuit (other than a dedicated monitoring device installed to indicate failure of the mains supply to the Alarms);
or
(b) a separately electrically protected, regularly used local lighting circuit.
The majority of home mains smoke alarms are powered from a lighting circuit. Both hard-wired interlinked alarms and those using the Radiolink-type bases.