Fire/smoke alarm system

[mk85]

I have mains wired smoke alarms on the landing of each floor (ground, first and second)

I need to put smoke alarms in all the bedrooms and reception rooms. I have accesss to run cabling (3 core and earth) to all the rooms on the ground and first floor to interlink them.

However i dont have acces to do that to the two rooms in the loft (second floor).

So my question is can i have cable interlinked smoke alarms to all the rooms on the ground and first floor, and have a radio interlink for the two in the loft rooms. (and run the supply from the lighting units)?

If i can, Would that mean that i would need 3 radio interlinked alarms in total. So id put one radio interlink in on the first floor which is also interconnected by cable, and then have the two in the loft which are only connected by radio link?

 

[Alarm]

1 x Radio base for the nearest detector.

2 X radio detectors run from adjacent lights on the upper floors.

As you said, but just a base for the highest wired.

Always assuming these are AICO.

If not swap the lot and use Aico as above. But add the standard wired ones to the lower levels.