safety of downlights

[soloheadbeg]

Hello

I have recently fitted a number of downlights (50W) and am just wondering how far the fibreglass insulation must be away from them. They have been fitted between the ceiling joists and the insulation id currently about 3 cm away from the light itself. As well as that there is a sheets of plywood resting on the joists effectively over the bulbs. is this ok?

Cheers

 

[ericmark]

Glass fibre will not burn and has quite a high melting point. However some of the stuff added to glass fibre will burn do you remember the old 3 wheel cars?

It also has some good insulating properties which does two things. Holds in heat and stops transfer of heat.

The problem is it can result in the heat being concentrated into an area which had their been free circulating air it would not get hot. This includes things like supply cables and the sockets that the lamps plug into.

So there can only be one answer. "Follow manufactures instructions".

Personally I think 50W in a 2" hole is asking for problems. It needs air to circulate behind the fitting and unless the fitting has some provision for air to circulate then likely a problem. I have non fitted into recesses all are of the pod type so have air around them.

 

[soloheadbeg]

Thanks for swift reply.

I have followed manufaturers instructions which stated that the fitting should not be covered with insulation. The fittings are suitable for use with 50W GU10 bulbs and low flammability materials such as wood and plasterboard. I'll increase the separation between the fitting and the fibreglass and ensure some air circulation.

Thanks again.

 

[mointainwalker]

Nothing is added to the glass-fibre used in the loft. Iit is classed as non-flammable.

The cars you referrred to were made of Glass-fibre Reinforced Plastic ( usually shortened to glass-fibre) and the glass-fibre was soaked in resin to form a permanent shape. The resin was the flammable part.

 

[ban-all-sheds]

I have recently fitted a number of downlights (50W)

FGS why?

//www.diynot.com/forums/viewtopic.php?p=1829057#1829057

//www.diynot.com/forums/electrics/led-downlighters-to-replace-lv-halogen.304757/

and am just wondering how far the fibreglass insulation must be away from them.

As far as the manufacturers say.

They have been fitted between the ceiling joists and the insulation id currently about 3 cm away from the light itself.

I'd be surprised if they say as little as that.

As well as that there is a sheets of plywood resting on the joists effectively over the bulbs. is this ok?

Depends on whether you regard insufficient clearance and therefore an overheating risk, lack of sealing leading to draughts and potential rotting of roof timbers and lack of insulation leading to higher heating bills and convection current soiling on the ceilings as OK or not.

You're going to be making holes in the ceiling, and there's a cold loft above - not only do you need to stop draughts coming down through the holes you need to stop air from the room getting into the loft.

If warm moist air from the room below gets into the loft, you can get condensation leading to rotting of the roof timbers.

Really you should have a sealed enclosure over the lights which will keep the insulation away from them so they don't overheat, support insulation over the top so that you keep the insulation you need, and act as a barrier to draughts and condensation.

You can either buy a pre-formed cover like this:

- it's not a firehood .

Or build something yourself out of plasterboard, as per the details here: http://www.nhbc.co.uk/NHBCPublicati...ical/StandardsExtra/filedownload,16553,en.pdf

 

[mointainwalker]

If warm moist air from the room below gets into the loft, you can get condensation leading to rotting of the roof timbers

A much greater liklihood is that the condensation soaks the fibre-wool which will more or less nullify its insulation properties.

 

[ban-all-sheds]

It will soak the insulation which has been moved away from the hole?

 

[mointainwalker]

Condensation will form at the physical point where the dew-point is reached. In a situation like a cold attic with warm, moist air rising from below, it is very likely that the dew-point will occur within the thickness of the insulating quilt.

 

[bernardgreen]

Use a mini extractor system to take the warm moist air from above all but one of the lights and push it back into the room via the last lamp.

The fan only needs to be a small one such as found in computor power supplies or similar http://uk.rs-online.com/web/p/energy-saving-fans/7406389/ is an example. There are other sources.

Not sure what building regs would say about it.