Insulation over LED downlights

donrkebab · 24 May 2019

SFK said:
Donrkebab,
The activation temperature of sodium silicate intumescent is about 110 – 120°C.
My understanding for fire rated lights is that as air temp at ceiling level increase, the metal fixing of light gets hot, and the intumescent material attached to the light expands closing the gap between lamp and ceiling.

For downlights the intumescent does not need any hot airflow through/past the light for the intumescent to expand.
SFK

So why did the op say "I checked online and found that they are NOT suitable to be covered with insulation".

Obviously the flow of air around anything depends on the shape, so depending on the design, the amount of hot gases needed for operation will vary. So there are possibly some that can be covered and some that can't, but these ones cannot be covered.

EFLImpudence · 24 May 2019

donrkebab said:
@EFL - Think of a fire door with intumescent sealing. The door has to be a loose enough fit to allow the hot gases to heat the intumescent material. If it was a tight fit the hot gases could not reach the intumescent material.

Precisely - so it wouldn't matter.

It's there because the door has gaps.

EFLImpudence · 24 May 2019

Ben565 said:
I don't have a copy of the instructions, couldn't find them online either

No. I can't find any.

You could ask Screwfix.

JohnW2 · 24 May 2019

Ben565 said:
From what I've read
- fire rated then ok to insulate over
- none fire rated then can't be covered, unless you use a hood and then you can.

It appears that you have read some nonsense, then - see earlier posts to explain what 'fire-rated' means.

Kind Regards, John

donrkebab · 24 May 2019

EFLImpudence said:
Precisely - so it wouldn't matter.

It's there because the door has gaps.

A very tight fitting door will prevent the hot gases reaching the intumesent material ie it will not fire seal the door.

JohnW2 · 24 May 2019

donrkebab said:
A very tight fitting door will prevent the hot gases reaching the intumesent material ie it will not fire seal the door.

If fire (flames) attempts to get around the door, it will inevitably encounter (and heat up) the intumescent material - whether the door is a tight or loose fit,

EFLImpudence · 24 May 2019

donrkebab said:
A very tight fitting door will prevent the hot gases reaching the intumesent material ie it will not fire seal the door.

Well, then it doesn't need to because the door must already be sealed.

No hole in wall, no hot gases escaping, no intumescent material needed.

donrkebab · 24 May 2019

If possible, read this with an open mind http://www.premdor.co.uk/pdf/download-centre/fire-door-fact-cards/fire-door-seals-mind-the-gap.pdf

JohnW2 · 24 May 2019

donrkebab said:
If possible, read this with an open mind ....

Done that - what next?

Ben565 · 24 May 2019

Interesting discussion regards fire doors, ours at work are on an automatic catch, if the fire alarm goes off they automatically unlatch & swing shut. As a fire marshal I understand the material around the edge of the door expands with the heat and seals the door. I've never really investigated the specifics of how this happens, I just know that it does.

Back to the LED Downlights though, I found an interesting article (s) here https://downlights.zendesk.com/hc/e...2?input_string=insulation+over+led+downlights

So it seems that it's ok to use a cap to cover it, and then cover with insulation providing you leave some gap (70mm) around the cap for ventilation. Looks like they might be the solution

EFLImpudence · 24 May 2019

donrkebab said:
If possible, read this with an open mind http://www.premdor.co.uk/pdf/download-centre/fire-door-fact-cards/fire-door-seals-mind-the-gap.pdf

Yes, I know that.

Note it is entitled "Mind the gap"

You gave an example of "A very tight fitting door will prevent the hot gases reaching the intumesent material ie it will not fire seal the door".
An unlikely scenario but it is your example.

So - it must be an already sealed door with no gap which will prevent the gases escaping to an escape route (corridor), therefore it is like a solid wall.

If intumescent material does not expand because it has not got hot enough because the hot gases have not reached it then all is well.

It's like complaining that a float valve has not closed because the water is not deep enough. It doesn't matter because the water is not deep enough to overflow.

EFLImpudence · 24 May 2019

Ben565 said:
So it seems that it's ok to use a cap to cover it, and then cover with insulation providing you leave some gap (70mm) around the cap for ventilation. Looks like they might be the solution

Yes, very likely but I would still ask Screwfix and get the instructions to be sure.

Ben565 · 24 May 2019

EFLImpudence said:
Yes, very likely but I would still ask Screwfix and get the instructions to be sure.

Will do

donrkebab · 24 May 2019

EFLImpudence said:
You gave an example of "A very tight fitting door will prevent the hot gases reaching the intumesent material ie it will not fire seal the door".
An unlikely scenario but it is your example.

I was trying to give a simple description, but you refuse to accept it, even though it is completely logical.

EFLImpudence said:
So - it must be an already sealed door with no gap which will prevent the gases escaping to an escape route (corridor), therefore it is like a solid wall.

How would you open a sealed door? shame you didn't bother to understand the link I posted.

EFLImpudence said:
If intumescent material does not expand because it has not got hot enough because the hot gases have not reached it then all is well.

Unless you have created a situation to prevent the heat reaching the intumescent material, by fitting the door too tightly (as the link explained) or sealing air gaps with insulation that prevents the flow of heat.

EFLImpudence said:
It's like complaining that a float valve has not closed because the water is not deep enough. It doesn't matter because the water is not deep enough to overflow.

???????

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Insulation over LED downlights

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