how much space around hologen lights

[CharlieB1981]

hi,

i'm taking up some floorboards on the 1st floor to do some work and want to take the opportunity to insulate between the ground and 1st floor.

planning to use rockwool slabs for this and have a couple of rooms downstairs with 50w fire rated halogen lights in.

how close to the lights can i get with the insulation and comply with regs etc?

many thanks

 

[PrenticeBoyofDerry]

There is no given distance, but I would suggest 150mm.
If the lamps are also powered via transformers they will also require ventilation.

 

[CharlieB1981]

thanks,

no transformers as these are mains voltage, but may be changed in the future, prob best to allow 200-250mm to allow room for these also in the possible future.

 

[PrenticeBoyofDerry]

Another point would be if your insulating the floor/ceiling void would be the existence of other electrical cables for powering of sockets, heating, cooker, shower. The insulation will likely change the reference method in which the installation was installed. This will lead to derating of the current carrying capacity of these cables.
http://www.tlc-direct.co.uk/Book/4.3.6.htm

 

[CharlieB1981]

hadnt seen it in these terms before but this is something that i think ive covered off - the joists are about 200mm deep, i've only half filled these with insulation and left the other half to allow room for cables to pinned out of the way and not to be covered.

 

[AdamCH]

Do cables laid on top of insulation (with plenty of space on top) also get derated? Thinking here of thinner insulation laid for sound isolation more than heat.

 

[Scoby_Beasley]

Do cables laid on top of insulation (with plenty of space on top) also get derated? Thinking here of thinner insulation laid for sound isolation more than heat.

Depending on the install method, but no, the cable wouldn't be derated due to insulation if it lies on top. Going through it/covered is the issue.

 

[CharlieB1981]

may be a daft question, but what about with insulation on top but a gap underneath. in my case there will be a gap of about 125mm between the ceiling below and the insulation. with heat rising would this cause an issue if there was ventilation underneath?

 

[Scoby_Beasley]

may be a daft question, but what about with insulation on top but a gap underneath. in my case there will be a gap of about 125mm between the ceiling below and the insulation. with heat rising would this cause an issue if there was ventilation underneath?

I've never thought of that one!! I put it down to me never making acquaintance with negative gravity, or helium filled, insulation!!

I'll hazard a guess (just a guess!!) at no. It's not the (trapped) heat rising from a cable, it is to all intents and purposes the cable being lagged and therefore unable to dissipate any heat build up.

 

[CharlieB1981]

helium fillied insulation... no idea of the thermal capabilities but thats an idea that could take off!!

 

[AdamCH]

may be a daft question, but what about with insulation on top but a gap underneath. in my case there will be a gap of about 125mm between the ceiling below and the insulation. with heat rising would this cause an issue if there was ventilation underneath?

What's stopping the insulation falling? Is it solid slabs?

 

[CharlieB1981]

couple of things, fairly solid slab tightly packed but also some small lathes pinned to the joist to form a tray. the stuff i'm using is accoustic slab as its going to be a bare wooden floor above, guidlines say to pack it as close to the floor as possible to reduce sound vibrations

 

[AdamCH]

Unless you form a tray with ply, it's going to sag over time isn't it? I was planning on laying the accoustic mat on the ceiling below - mainly to try and damp down the sound of a teenager who thinks he's Bob Dylan.

 

[CharlieB1981]

if you dont put pieces across between the joists then yes it may sag over time, what i've done is effectively made a shelf between the joists at 200mm intervals - each one is only 20mm wide but it should be enough to support it. could always staple some netting between them too i suppose for extra support