What are the basicas of fire alarm install rules... really

[Steve2381]

I think that may be the issue. The offices are just studwork and timber joists with a suspended ceiling hung underneath. No plasterboard on the ceiling.
I think I will run tray on the top of the joists, and tie-wrap to that.
At least the cable will be supported for 3m lengths of tray. If that much of the building has burnt down that 3m of tray has collapsed, then I am not sure what more I could do anyway.

 

[tazz]

First you have 2 issues here, first the detection in the warehouse area, then then detection within the offices themselves. So the routing of the cable will first be brought through the warehouse for the high level detection. And that will need supporting to the main structure. One method would be to come off the main tray or trunking within the warehouse a copex down to each sensor back bezer box, dependent on height. My concern is how are you installing the electrical containment, this also requires the same care and attention to installation. Accepted method on cable ties is every third cable tie is steel.

 

[Steve2381]

The main warehouse already has a run of spare 4" tray secured along the ridge of the building, with a couple of handy tray 'spurs' off this run. Nothing else on this tray, so the cables for the 2x sensors + sounder/strobe bases will run on that.
The warehouse isn't that big, so there are only a couple of sensors.
But, there isn't anywhere to drop from this tray to hit centre of the rooms for sensors (and it would look awful).
Only other option would be to suspend tray from the main roof using steel wire just above the rooms, but access etc would make that a nightmare (plus it seems totally overkill and boss man ain't going to fund that).
I know he will just say fix tray on top of the joists and fix to that. Without knowing a better way, I can't really argue.