Wiring run for two linked mains powered smoke detectors goes like this: Consumer unit -(T&E)- detector 1 -(3 core & earth)- 20A 4 terminal junction box -(3 core & earth)- detector 2 My question is is there any regulation that prohibits the use of a junction box in a linked smoke detector circuit?
131.1.1 Good workmanship... Why the JB? If you're installing use a piece of cable long enough. Quote TallPaul http://www.screwfix.com/talk/thread.jspa?threadID=110773&tstart=45 1) Why [have they used] ANY junction boxes (JBs) on a new installation? All cable joints should be at terminals. Either socket outlets, light switches or light points. {or smoke detectors} They can't say "the cable wasn't long enough". Get more cable Muppet!
Hear, hear Booky. If it's already in place, junk the jb in favour of properly connected joint using crimps.
I think the detectors were original powered from a lighting circuit before it was put onto a dedicated circuit. I think I can see a line of holes from old cable clips leading away from the box into the darkness as if there had been a third cable. What I haven't seen is any evidence or need for a third detector hence my theory of it being linked to the lights.