When wiring smoke alarms i prefer to wire off a regularly used lighting circuit, now i read last week and i have not got the publication to hand that there should be a means of isolating them from the supply for servicing, but there must surley be a temptation for the user to isolate them if they get nuisance alarms when making the sausage sandwiches. would an unswitched fused spur be a solution? but that would easily be removed by a half intelligent half foolish person. Who installs isolation for smokes?