Safety service

Nothing to do with the cable type supplying Safety Service. Emergency lighting, unless the supply is from a Central Battery Service or a UPS, is usually  in T&E.

For you argument to work a safety Service would be defined by the cable type supplying it rather than as Defined in Part 2 of BS 7671 and the list in Chapter 56.

Not defined by its cable type, but the cable type is a direct consequence of the definition - if we consider a domestic battery backed-up smoke alarm to be a safety service and the cable that supplies it is a circuit of a safety service then 560.7 and 560.8 would apply and we'd have to go down the FP/pyro route. Since all the advise and guidance says otherwise, there must be something wrong somewhere...

(I suspect that chapter 56 (and associated guidance) was written with only the problem of maintaining power to the device in mind, and now BS 7671 has expanded to consider other effects (e.g. damaging spikes/surges) that might disable a safety service even though the backup supply remains intact, it might be time for a rethink).

   - Andy.

Nothing to do with the cable type supplying Safety Service. Emergency lighting, unless the supply is from a Central Battery Service or a UPS, is usually  in T&E.

For you argument to work a safety Service would be defined by the cable type supplying it rather than as Defined in Part 2 of BS 7671 and the list in Chapter 56.

Not defined by its cable type, but the cable type is a direct consequence of the definition - if we consider a domestic battery backed-up smoke alarm to be a safety service and the cable that supplies it is a circuit of a safety service then 560.7 and 560.8 would apply and we'd have to go down the FP/pyro route. Since all the advise and guidance says otherwise, there must be something wrong somewhere...

(I suspect that chapter 56 (and associated guidance) was written with only the problem of maintaining power to the device in mind, and now BS 7671 has expanded to consider other effects (e.g. damaging spikes/surges) that might disable a safety service even though the backup supply remains intact, it might be time for a rethink).

   - Andy.