Safety service

I am in no doubt that smoke, heat and CO detectors are  Safety Services.

The actual detector may be a safety service, but whether the circuit supplying it is a safety circuit might be a different issue.

If it were deemed to be a safety circuit then we'd be wiring domestic smoke detectors in Pyro or FP rather than T&E, have a UPS and/or backup generator for them and be supplied from switchfuse connected upstream of the main switch, and inaccessible or ordinary persons. The fact we don't was, I thought, explained by the safety source being deemed to be the internal battery, rather than the mains.

I thought that Mark Coles's comment about SPDs was in relation to that - we don't treat domestic smoke alarm circuits as safety circuits, but nevertheless it might be a good idea to provide SPD protection for them.

   - Andy.

I am in no doubt that smoke, heat and CO detectors are  Safety Services.

The actual detector may be a safety service, but whether the circuit supplying it is a safety circuit might be a different issue.

If it were deemed to be a safety circuit then we'd be wiring domestic smoke detectors in Pyro or FP rather than T&E, have a UPS and/or backup generator for them and be supplied from switchfuse connected upstream of the main switch, and inaccessible or ordinary persons. The fact we don't was, I thought, explained by the safety source being deemed to be the internal battery, rather than the mains.

I thought that Mark Coles's comment about SPDs was in relation to that - we don't treat domestic smoke alarm circuits as safety circuits, but nevertheless it might be a good idea to provide SPD protection for them.

   - Andy.

I think I'm with that as being the only interpretation for Grade D1 & D2 systems (and wired interlinks for Grade F1 and F2 systems).

Grade A and Grade C are of course a different kettle of fish.