Question:
Screwfix linkable alarms (0347) There are two live in and a white wire to link There is no mention of what signal goes on the white wire What sort of wire should be used? 1. I assume using T&E would break the regs (I..e. using earth as the white signal wire) 2. Can I use alarm wire to link between alarms? Also it suggests to wire into the lighting circuit – which would man that you can not isolate the smoke alarms – does this sound right? I was going to put an isolation switch on the smoke alarm run – would this be wrong?

Answer: Q: 1. I assume using T&E would break the regs (I..e. using earth as the white signal wire) 2. Can I use alarm wire to link between alarms? A: Possibly - depends on the voltage on the link wire. As that model has a battery backup, it is highly likely that the link voltage is the same as that of the battery, so alarm cable should be ok. Q: Also it suggests to wire into the lighting circuit - which would man that you can not isolate the smoke alarms - does this sound right? I was going to put an isolation switch on the smoke alarm run - would this be wrong? A: Yes - the point is that you don't want them being switched off by anyone. For this reason, wiring them to the lighting circuit is more desirable, although a separate dedicated circuit would be ideal. Don't attach them to any circuit with an RCD - the last thing you want is the alarms being deactivated when there is a fault.