Need to fit some smokes to some 2ftx2ft ceiling tiles of the floppy Rockwool type.

What methods do you use for this, use a different tile, plywood backing?

Keep the tiles for aesthetic reasons, but back with a piece of plywood slightly smaller than the tile and fix the smoke through the tile and plywood and into a galvanised stop end or "U" conduit box with some long M4 screws and the relevant glands on the cable entries. I would never do it myself but you could fix them to the metal grid of the ceiling too.

Dont forget to PClip the cables

As above . Use plywood as a backing and a galv box . And stuffing glands

It can be a bit of a pain to do but makes the job right . ( at least the way I'd do it )

Nah,just screw into the tile with a inch an quarter no8 woodscrew-so it looks the part and prog as final exit-NSI here I come,lol!.

Twas a jest peeps!.

As standard we use galv boxes with ply but why the use for galv boxes?

The cable is already p clipped to the detector so no chance of cable falling down?

I read it as smoke on an intruder system, so probably 8 4 core

Its a non conformant addition,no standards/requirements apply,therefore do as one feels fit,recent previous threads cover it all-or not-as the case may be!.

So another do what you want but some inspectors will agree and some will not with the install?

Fire on intruder is ancillary reg wise. If you want to comply then 5839 is your reg