Fried Downlights - Condensation?

If the ceiling void is well-insulated, why is it cold beneath the insulation?

Uh long story, there was a mistake with the size of the windows and the height of the ceiling. Essentially the ceiling had to be lowered slightly by 50mm so that it can line up with the rest of the open plan ground floor. The windows however have already been sized and fitted. Essentially the 30mm void between the plasterboard and the vapour barrier lines up with the the trickle vents of the windows essentially allowing a breeze to blow through the void.

The temperature isn’t very cold but you could feel a slight temperature variation.
 
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you take off the outside canopy, gaffa tape over the vent and stick the canopy back.

I would try sealing the TVs and see if it sorts your problem.

I cant see any advantage to passive ventilation going into the ceiling void.
 
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you take off the outside canopy, gaffa tape over the vent and stick the canopy back.

Good plan! Will give that a try. Got 2 more spare leds to fry.

The downlights must comply with Part C do they do not duck up moisture and deposit in the roof void.
https://www.planningportal.co.uk/in...n_and_resistance_to_contaminates_and_moisture

I don’t see anything about downlighters on part c? In terms of the roof, I believe appropriate measures have been taken to resist moisture? I.e vapour barrier?

I’ve added a picture of the inside of the LED. In one day the circuit board connectors rusted. And I still see moisture on some components. The paper layers are still soaking.

Strange that the 2 that fried are in the same place as shown in the 3rd picture
 

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The issue is embedded in para 6.12.
Other info
https://www.downlights.co.uk/faq-how-do-i-comply-with-the-building-regulations-.html

Downlights that provide resistance to the passage of moisture (“Part C compliant”) are widely available.
Eg
https://www.medlocks.co.uk/avenger-led-downlight-dimmable-8w-620lm-4000k-ip65

Yeh I don’t think my lights are part c compliant. They seem to be a crappy China import.

However seems BCO or Electricians don’t look that in-depth into LED lights, as mine have been signed off by both.
 
Ok, so I’ve taped up the vents. And put the new light in. Been about 2 days, and hasn’t blown yet.

I wonder if the vent caused a breeze which made the lights cold, resulting in loads of condensation forming on then lights.
 
ventilation usually blows the water vapour away.

when did it last rain on this flat roof of yours, with the wet patches?
 
when did it last rain on this flat roof of yours, with the wet patches?

What do you mean?

The lights did blow last week during rain. But discounted any leaks as it was dry in the void and water was only inside the light and not around its casing.
 

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