Safety service

Question

Are smoke/heat/CO detectors connected to the electrical installation in domestic premises a &ldquo;safety service&rdquo; as defined in Part 2?

AJJewsbury · Answer

Off the top of my head, as long as the detectors have built-in backup batteries, then the mains supply to detectors isn't considered a safety circuit (rather just a convenient means of re-charging or an alternative to the safety source). 
 I might wonder about the interconnecting wiring in the case of a interconnected system though... 
 - Andy.

gkenyon · Answer

I think I agree with Andy ... Isn't the interpretation of this partly within BS 5839-6, and the Grade of the system? Clause 110.1.3 and indent (v) to that regulation, effectively says that BS 7671 isn't stand-alone for fire detection and fire alarm systems, and that BS 5839 supplements BS 7671 in this respect. 
 It's what differentiates a Grade D1 and D2 (and, if considering the interlink cable, F1 and F2) systems from Grades A and C systems? Clause 16.4 a) of BS EN 5839-6 appears to indicate that normal domestic mains cable is OK. Compare with the requirements for cable types for Grades A and C systems in Clauses 16.2 and 16.3 ?

Safety service

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