Low Voltage Downlighters in Sloping Ceiling

[astroman]

Hi All,

Can anyone give any advice on my latest problem?

Part of my new extension has a sloping roof, this is to be insulated, between the 150mm rafters with 135mm celotex type solid foam insulation boards, then plasterboarded out. Due to the ceiling hight and slope I had hoped to instal a number of LV downlighters, probably 20w in the sloping ceiling. Can anyone advise on how I should route the cables? I understand that it is not good practice to bury them in the insulation material. Would it be acceptable to cut a channel in the insulation foam or would I be better installing some plastic trunking, also what size & type of cable should I use from tranformer to lamps? How much of a cut out in the foam should I allow round the lamp fittings - as you know they get pretty hot!

Thanks,

Chris

 

[Sandy Beech]

If it is anything like my sloping ceiling there will be insufficient space above the the downlighters for heat dispersion to be effective. The risk therefore will be the overheating of the lamps and potential risk of combustion!

 

[astroman]

Hi Alex,

Yes, I see your point - the clearance from the underside of the plasterboard to the underfelt is 150mm, I had hoped that this would be enough given sufficient space around the light fitting hence my question.

To widen my initial question slightly, does anyone know what the best practice is for ceiling wiring where the loft space is insulated with rockwool in blanket form 100mm thick + 150mm. In all the lofts I have been in the wiring just seems to be laid haphazardly over, under & between layers of insulation blanket. Should it be clipped, under the blanket, or is it ok to just let it rest on the insulation material ?(the loft will not be regularly accessed so there in no real danger of mechanical damage to cable or fittings.)

Chris