Smoke alarms

And I suppose it needs to be 1.5mm as it's not a lighting circuit?

 

The thing that is a pain in the **** is that you don't get to check if the ctt is truly "radial" in the pure sense of the word as you have two points to test to make sure that the interlinks are connected, whcih you do do don't cha

 

Not that I would recommened wiring a smoke off a spur on a radial as I don't know if it would work or not

 

Also I would say there is a strong argument to stick with 1mm for smokes as the ctt length can be very long given the volt drop requirments must hardly anything at all. It won't make the ctt. any safer using 1.5mm so I can't see why a depareture note shouldn't be enough in the ceryt.

 

Also Col it could be a real struggle to get 2 x 1.5's into a smoke alarm. I've used mainly Aico and there's not a lot of room available.

 

You run around the property like a loon making sure they're all going off.

Or forget about the 3-core and use radio bases. Very exp£n$ive though, but my past few refurbs have used them for getting from floor to floor. In an HMO they were great as one was required in each room as well as hallway & landings. Along with the radio test-switch, that job took a good couple of month's rental income from the owner...

Back to the OP though... I use 1mm for wired ones regardless. The departures bit of the form is good.

 

Dont matter on interlinked, they're all commoned and interlinked, only time it makes a difference is if it's a dedicated fire alarm that monitors head removal/faults etc.

 

As Rulland said, its just an interlinked signal so it doesn't matter how they are wired.

 

Star wired is often easier, and perfectly fine. Quite often take two 3 cores to the CU, jointing the interlink internally to the CU. What ever way the cables go in the quickest and with least length.