CPC used as interconnect on smoke detectors

[bigspark17]

If the interconnection cable is elv band 1 and a 3core is installed between heads using a core as the interlink isnt this aggainst reg 528.1 (segregation of band 1& band 2 cables)

 

[S P]

No it's covered by 528.1 (ii)
Quoted from the thread I linked at the start:

Either way if it is 230v AC or a 9v DC signal..
The conductor it travels down should be insulated along its length as either

a) if at 230v it is a live part and must be insulated or out of reach etc... 416.x.x

b) if at 9v (or similar) it is mixed voltages in the same cable and conductors should be insulated to the level of the highest voltage present! 528.1 (ii)