False ceiling and Low Voltage Lights

What is the minimum height for Low Voltage lights in a false ceiling, using 35w lamps - would 20cm be plenty?
I wanted to put Celotex in the space to try and insulate the room, I live in a flat with 10ft ceilings. What would be the best way to do this, with the lights? I would need to create spaces without Celotex to disapate the heat. I could create boxes/channels lined with Plaster Board.
Anything else I should think of?
thanks gna
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using
The more air circulation around the lights the better, so putting sealed boxes around them will only capture the heat inside the box. Just make sure you leave the celotex about 25mm to 30mm away from the edges of the lights and leave some air movement to flow around the fittings.
200mm will be enough space above the light fittings.
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gna03633 wrote:

That is the way to go.
The units get very hot, but the heat does dissipate back into the room via the unit itself, and surround ceiling.
The biggest problem is keeping the transformers cool. They DO need some airspace to work in - plus sufficient area of plasterboard to allow heat to dissipate.
The volume of air is not the issue, so much as free circulation of hot air within the cavity to allow it to transfer to the plasterboard, and thence out into the room.

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