Ceiling Spots, Plasterboard and Insulation

[stem]

I've purchased some 50W 230V halogen spots for my kitchen extension. The instructions say that they should not be mounted from a combustible surface. wouldn't plasterboard classed as combustible seeing as it has what appears to be a paper surface?

Also the instructions say that the insulation has to be 140mm away from each side of the light & as the light is 90mm dia. This means that a 370mm square piece of insulation will be missing for each light. As there are 6 lights almost 5m2 of ceiling insulation will be missing which equates to 25% of the total kitchen ceiling. The builder thinks that the LABC will have something to say about that (Part L?) How can I restore the insulation value of my ceiling, with out introducing a fire risk or compromising the lamps?

I've searched for threads on this, but can't seem to find a definitive answer. What do the professionals do?

 

[ban-all-sheds]

I've purchased some 50W 230V halogen spots for my kitchen extension. The instructions say that they should not be mounted from a combustible surface. wouldn't plasterboard classed as combustible seeing as it has what appears to be a paper surface?

No, because the plaster itself doesn't burn very well...

Also the instructions say that the insulation has to be 140mm away from each side of the light & as the light is 90mm dia. This means that a 370mm square piece of insulation will be missing for each light. As there are 6 lights almost 5m2 of ceiling insulation will be missing

Err.... 0.82m² according to my calculations....

which equates to 25% of the total kitchen ceiling. The builder thinks that the LABC will have something to say about that (Part L?) How can I restore the insulation value of my ceiling, with out introducing a fire risk or compromising the lamps?

Unless you have access, and sufficient depth available, to build a structure over the lights which you can then cover with insulation, you can't.

 

[Pensdown]

http://www.lyco.co.uk/category-contents/Fire.htm?catID=1731

If you use these with a transformer your problem will be solved. IMO the SELV lamps are also crisper than GU10's

 

[ban-all-sheds]

If you use these with a transformer your problem will be solved.

No they won't, as a 50W SELV lamp puts out just as much heat as a 50W LV.

And those hoods restore fire ratings (probably unnecessary) not insulation rating.

And their "fully breathable intumescent material allows lamp heat to be dissipated preventing the terminal block and fitting from overheating" property will be negated if insulation is piled up against them.

 

[Pensdown]

If you use these with a transformer your problem will be solved.

No they won't, as a 50W SELV lamp puts out just as much heat as a 50W LV.

And those hoods restore fire ratings (probably unnecessary) not insulation rating.

And their "fully breathable intumescent material allows lamp heat to be dissipated preventing the terminal block and fitting from overheating" property will be negated if insulation is piled up against them.

I was refering at the light fittings not the hoods...£ 7.25 each

http://www.lyco.co.uk/products/---H...ght-with-Itegral-Fire-Barrier.htm?prodID=5672

 

[ban-all-sheds]

OK - sorry.

Still don't know though how much clearance those luminaires need....

 

[Adam_151]

No they won't, as a 50W SELV lamp puts out just as much heat as a 50W LV.

SELV fittings would actually be worse, would they not, as they are cool beam as opposed to PAR ?

 

[RF Lighting]

It depends on the lamp type.

Lamps with dichroic reflectors throw the heat backwards (cool beam)

Lamps with aluminium reflectors throw the heat forwards (not cool beam)

The fitting pensdown linked to must only be used with aluminium reflector lamps, and not with dichroics.

Both types of lamps are available in LV and SELV

 

[stem]

Thanks for all your comments guys to summarise my understanding is:

1. Ban you're right I calculated the exposed ceiling per light and must have multiplied it by the number of lights (6) twice. Thought it was a bit excessive. That's resolved much of the problem (five 6ths to be precise)

2. The hoods give fire protection to the loft space, but do not provide heat insulation as they have to breathe, covering with insulation will prevent this leading to overheating.

3. I understand that the intumescent lamps only seal the opening in the ceiling in the event of a fire, hence are open the rest of the time and work as traditional lamps still needing clearance for heat dissipation. Is this correct?

4. If I construct plasterboard boxes to give the clearance specified by the manufacturer and then cover with insulation that will be OK.

 

[Steve]

loft doesn't need fire protection.

FIRE HOODS ARE ONLY REQUIRED WHERE THE FIRE RESISTING CHARACTERISTICS OF THE CEILING ARE ESSENTIAL TO COMPLY WITH BUILDING REGS. Basically, this means between 2 flats and between a downstairs garage and a room above.

And at £10-15 a pop, you ought to be glad to hear this too.

 

[Job_n_knock]

If it was me Id use LED fittings instead. But if you must use LV halogen, make sure theres no insulation around each fitting by about 6" round.