Spotlights under a flat roof - any fire hazards?

[Hallsy]

I am currently renovating my downstairs toilet/hallway. Originally this was a porch way which was bricked up. It shares a flat roof with the garage as the porch was adjacent to the garage.

In the bathroom and part of the hallway (which is part of the flat roof section) I will be fitting 3 halogens. The joists are 4" deep under a flat roof, this will be insulted with 4" fibregalss and then boarded up.

I presume that the depth of the joists will be fine for adequate ventilation, but will the roof covering be OK? Also is it best to just not put any fibreglass at all in the void where the spotlight will be?

Secondly, as it's a bathroom they will be ELV spots with transformers, in the hallway however I can use either mains or ELV. Which are better to use, should I use all ELV around the house (if I fit more in time) so bulbs are same, etc or do mains ones have better lamp life?

Thridly (yawn!!), I'm wondering about how many to mount, I haven;t botherd doing any lumen level calcs for the rooms, if anything it's more about aesthetics so says the missus!!

The bathroom is small at 1.5x0.9m with a low ceiling height of 2.1m. I said that one 50W spot would prob be enough but she said she wanted two, would two 35W be OK or slightly overkill?

The remaining part of the flat roof section is part of the hallway at 1.3x0.9m again with the smae height ceiling, I reckon that 1 50W spot should be enough in here, with another in the other part of the hallway 1.8x0.9m but with 2.4m high ceiling.

Any thoughts on this?

 

[Steve]

I dont know anything about calculating lumens, but i would say have 2 20w LV spots in the bathroom, partly because it is a low ceiling and the spot beams aren't very wide with a low ceiling. use 20w because any more and it will be too bright IMO.

You are right with the hallway, one 50w should be enough.

Don't put any insulation in the roof above the lights, leave, say a square foot for adequate ventilation. Roof covering will be fine.

 

[Hallsy]

Cheers crafty,

am I better off using ELV's all round, or only in the bathroom/kitchen?

 

[baldelectrician]

http://jcc-lighting.co.uk/files/inst_sheets/JC3007InstSheet.pdf

I always use 12V lights if I am fitting spots.

I usually use JCC ones and have never had any problems, data sheet is above.

Although you will be very unlikely to dim bathroom lights, you can dim 12V trannys / lights easily, They are ideal in halls and landings (night lights for kids)

 

[Hallsy]

Thanks, I suppose there are pro's and con;s for either. With mains you only have to replace the bulbs if they blow, but if you have all ELV then you only need to keep one type of bulb as spares.